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GM Bob
GM Bob, ASE Certified Technician
Category: Chevy
Satisfied Customers: 1074
Experience:  30 plus years. experience as GM technician, ASE Master Technician and GM Certified.
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My park lights and license lights flash with the turn

Customer Question

My park lights and license lights flash with the turn signals.
Submitted: 1 year ago.
Category: Chevy
Expert:  Tool Hut replied 1 year ago.

Hi, My Name is ***** ***** for posting your question to just answer. I am a independent contractor for just answer, and ASE Certified Master Auto Technician with 20 years experience. I am confident we can resolve your problem together.Please remember I don't know your skill level. I can't see, smell, hear, or touch the vehicle. It may take a few back and forth replies to get to a satisfactory resolution.I also try to give all of the information you may need expecting a positive rating. I am not compensated for my time until you leave a positive rating.

What you definitely have is a bad ground.

Customer: replied 1 year ago.
Thanks for taking the time to look at my question Sam. How do we go about tracking down where the bad ground is and ultimately fixing it? I have a test light and dmm if that will help.
Expert:  Tool Hut replied 1 year ago.

A visual inspection would be easiest to start with. Back by rear bumper inspect grounds. At left rear of the cab look for a bad ground and the left side of radiator check those grounds. They should be clean and tight.

Customer: replied 1 year ago.
Sorry for the delay, I will have more time to look this weekend. Where are the ones by the rear bumper? I tried looking and did not see them. I think there is supposed to be one on the left rear framerail on the outside. I found a braided ground strap that connects to the back of the fuel door. Was this the one for the rear of the cab? Were do you look to see the radiator one, top, bottom, or do I need to remove something?
Expert:  Tool Hut replied 1 year ago.

You should not need to remove anything. The ground on rear should be attached to the back of the cab at the cab mount. There should also be one on the frame rail on left rear. The radiator ones may require a flash light or removal of a couple of things. It should be on engine side of radiator support

Customer: replied 1 year ago.
The grounds I could find are all firmly attached. The ones I found were:
Left lower radiator support two wires on one bolt G100
Behind left front tire on cab frame support three wires on two bolts G302? G110?
Behind fuel door and connecting to under bed rail mount, this is a braided strap
Above spare tire one wire to one bolt, I can't get my head in there but can feel the wire is connected to the ring terminal.
Expert:  Tool Hut replied 1 year ago.

I am out of ideas. I am going to opt out and see if someone else can help

Expert:  GM Tech (Cam) replied 1 year ago.

Hi there, I might have some ideas? You said you have an LED in there somewhere?

Customer: replied 1 year ago.
All external lights are led except cargo. Only the front 3157 turn signal lights have built in load resistors. No cutting or splicing involved just plug and play.
Expert:  GM Tech (Cam) replied 1 year ago.

Ok, if you disconnect the rear junction block, does this still happen?

Customer: replied 1 year ago.
With all four plugs disconnected from the rear junction block and the tow plug in the bumper. The front 194 led on the opposite side as the selected turn signal blinks at normal brightness instead of a faint flicker.Not sure if it is ok to post this but here is a thread on the troubleshooting I have done.
http://www.gmfullsize.com/threads/park-lights-flash-with-turn-signal.302532/
Expert:  GM Tech (Cam) replied 1 year ago.

Let me review this and get back to you. It may be morning.

Customer: replied 1 year ago.
That is fine, thanks for taking the time to review my question. Not sure if it may help, but I tried a test light on the trailer plug. When the running lights would flash the test light was not as bright as the turn signal. I then tried my dmm on the trailer plug running lights while they were flashing and it was 2-5 volts if I remember correctly. My meter could not read it fast enough.
Expert:  GM Tech (Cam) replied 1 year ago.

if you test with your meter on the plug into the junction block, does the test light flash or light up as it's supposed to for each circuit?

Customer: replied 1 year ago.
I only checked the tow plug at the bumper with the test light. Are you asking about the blue plug that supplies power to the distribution block? I do not have a pin out for that.
Expert:  GM Tech (Cam) replied 1 year ago.

Yes, blue plug.

Dark green and yellow are signals, light blue is brake and tan and tan black are park lights.

Customer: replied 1 year ago.
I will try and check tomorrow.
Expert:  GM Tech (Cam) replied 1 year ago.

ok

Expert:  GM Tech (Cam) replied 1 year ago.

I just picked up on something. You said that the opposite side front marker light flashes when you turn the signal light on?

Is it both sides?

Customer: replied 1 year ago.
the marker lights opposite of the selected turn signal flash. Happens on both sides, meaning either turn signal can make the opposite side marker lights flash. For example, with the headlights off and left turn signal activated. All the proper left turn signal lights blink like they should AND the left rear top 3157 park light, license plate lights, right rear top 3157 and bottom 194 park lights blink. Also the right front 194 led will flicker very faint. The dash indicator and mirrors function correctly. I think a few volts are "bleeding" from the turn signals to the park lights. For traffic behind me it looks like I'm using my hazards instead of turn signals. My temporary fix is just turn the headlights on manually every time.
Expert:  GM Tech (Cam) replied 1 year ago.

Is there any shorted wires under the fuse block under the hood?

Also if you supply a new ground for each front light assembly, does it change?

Customer: replied 1 year ago.
I took apart the under hood fuse block and all looked good, no signs of mice.
Expert:  GM Tech (Cam) replied 1 year ago.

Try a new ground from each front signal light as a test next please.

Customer: replied 1 year ago.
Not sure if or how this might be related. When I tap on the dash bezel just below the headlight knob my headlights go out and the dash lights, radio and climate control lights go to full brightness.
Expert:  GM Tech (Cam) replied 1 year ago.

Ok, that may be everything. Is there signs of moisture under there? How about the wiring to the BCM under the dash directly under the steering column?

Customer: replied 1 year ago.
I unplugged the headlight switch and the park lights still flash. No signs of water or corrosion on the plug. I looked at the BCM and do not see any signs of water.
I checked the voltage at the pins for the C-1 rear chassis harness connector (blue plug at rear of truck)
no lights on left turn on right turn on
A 0.03 6 to 11 0.17
B 3.52 3.59 3.55
C 0.33 0.35 0.32 14.20 in reverse
D 0.68 3 to 5 3 to 5
E ground 0 ground 0 ground 0
F not used not used not used
G 0.68 3 to 5 3 to 5
H 0.01 0.07 6 to 11All measurements were taken with the engine running and using the trailer pin for a ground. Trailer ground to pin E was checked with meter set to 20K ohms and read 0.00. Sorry I do not have a auto ranging meter.I didn't get a chance to run a temp ground for the front signal lights. The sockets looked like they can be back stabbed or do I need to cut the stock wire to add the temp ground? Would checking the resistance from the socket back to the battery tell anything?
Expert:  GM Tech (Cam) replied 1 year ago.

Are these resistance, I was looking for voltage on the 20V scale.

Customer: replied 1 year ago.
The table is dc voltage, sorry about the confusion. I was using resistance to verify my trailer ground was good to free up a hand. I should of set the ohm range to 200 instead of 20k.
Customer: replied 1 year ago.
The table was on the 20v dc scale
Expert:  GM Tech (Cam) replied 1 year ago.

Ok and if you test same power at the fuses in the underhood fuse block for the tale lights and left dash for stop/turn for each side, do you get the same voltages?

Customer: replied 1 year ago.
For checking voltage at the fuses do I use the metal points on top of the fuse, like you do to find a blown fuse or remove the fuse and probe the fuse panel contacts?
Expert:  GM Tech (Cam) replied 1 year ago.

Yes, exactly. Some you were getting battery voltage, others not so much. I need to see if we are getting battery voltage at the pins of the fuse to ground with the circuit active.

Customer: replied 1 year ago.
no lights on left turn on right turn on
under hood
TRL PARK 0.71 3-5 3-5
RR PARK 0.71 3-5 3-5
LR PARK 0.71 3-5 3-5
FRT PARK 0.70 3-5 3-5
INTPARK 0.70 3-5 3-5
STOP LP 14.50 14.40 14.38
left dash
VEH STOP 2.28 2.70 2.70
BRAKE 14.36 14.35 14.35
VEH CHMSL 2.28 2.70 2.70
LTTRLR ST/TURN 2.28 5-11 2.70
RTTRLR ST/TURN 2.28 2.70 5-11
LT TURN 0.05 5-11 0.20-0.45
RT TURN 0.03 0.20-0.45 5-11
Expert:  GM Tech (Cam) replied 1 year ago.

So if I am reading this correct, only the stop lamps and brakes fuse did you get full voltage on.

Customer: replied 1 year ago.
that is correct
LTTRLR ST/TURN, RTTRLR ST/TURN, LT TURN, RT TURN had a range of 5-11 volts when the corresponding turn signal was selected. My meter could only read the voltage so fast and that is the range that the numbers flashed between.TRL PARK, RR PARK, LR PARK, FRT PARK, INTPARK had a range of 3-5 volts when any turn signal was selected. Again my meter could only read the voltage so fast and that is the range that the numbers flashed between. I think these should all be zero or close to it. All of my readings were taken with the truck running and headlights/parklights turned off. Like it would be in the daylight.
Expert:  GM Tech (Cam) replied 1 year ago.

OK, I would like you to disconnect one at a time the cluster, then each front light assembly with the rear installed to see if this changes anything. .

Customer: replied 1 year ago.
After unplugging the cluster and looking for any change, do I plug it back in or leave it unplugged? On the front lights, after I remove one do I put it back in or leave it out and move on to the next?
Expert:  GM Tech (Cam) replied 1 year ago.

Leave each item unplugged and test the lights in each case, then plug back in and move on to the next.

Customer: replied 1 year ago.
Unplugging the cluster did nothing.
Unplugging the left 194 light and using the left turn both license plate lights stop.
Unplugging the left 194 light and using the right turn the left license plate light stops.
Unplugging the right 194 light and using the right turn the left license plate light stops.
HI, LOW, and DRL removed and nothing changed.
Expert:  GM Tech (Cam) replied 1 year ago.

Am I understanding that with the 194's out of the front it was better?

Customer: replied 1 year ago.
Expert:  GM Tech (Cam) replied 1 year ago.

Did all issues stop with the 194's out?

Customer: replied 1 year ago.
No, it stopped one or both of the license plate lights from flashing. I did not remove both 194's at the same time.
If I remove one of the front led amber turn signals, doesn't matter what side, and replace it with a 3457 incandescent bulb. The turn signals appear to function normally. Until I turn on the hazards, then the license plate lights flash. If I put 3457 incandescent bulbs in both front turn signals. The hazards and turn signals appear to function normally.
Expert:  GM Tech (Cam) replied 1 year ago.

So if I am understanding this correctly, it’s a light bulb issue. Normal bulbs results in normal operation?

Put in a ll normal bulbs and test please.

Customer: replied 1 year ago.
I think all my led's are good. I traded all four of my front signal lights with another 2004 Silverado that is bone stock. That would make mine incandescent and the other led in the front. Both trucks acted normal with turn and hazard with the swapped bulbs. I checked my trucks clearance lights at the trailer plug with my multi meter and it peaks at about 3 volts.
Customer: replied 1 year ago.
I went out after it was totally dark to put everything back and look one last time. With both front 3157 led's in the donor truck and the hazards on, both license plate lights barely glow. Have to about put your face right over the license plate light to see it. The donor truck does not act up with only one led or with the turn signals. It must be both 3157 led's and the hazards on. The company I ordered the led's from is sending me some replacements to see if this might fix my problem.
Expert:  GM Tech (Cam) replied 1 year ago.

Ok, Do the interior lights operate As low?
I think we are making headway. What I am thinking now is there is a power supply issue or connection issue to the park lights. I would remove the park light relay and test power with a test light there. See if the light is bright. Swap relays to see if the lights are bright due to a bad relay.

Customer: replied 1 year ago.
The interior lights appear normal.
I swapped the park lamp and starter relays prior to asking on here and noticed no change, so I didn't switch them back.
Expert:  GM Tech (Cam) replied 1 year ago.

Ok, testing power supply with the test light at the relay, as bright as testing the battery?

Customer: replied 1 year ago.
At pins 87 and 85 the test light is the same brightness as at the battery 14.6 volts at all three. Zero at pins 86 and 30. The problem still occurs with the park lamp relay pulled.
Expert:  GM Tech (Cam) replied 1 year ago.

OK, so if you put power to the brown at one of the lights with the relay out, do the rest of the park lights go bright?

Customer: replied 1 year ago.
I think there might be some confusion here. My issue is when the headlights and park lights are turned off. If I use a turn signal it will make the license plate lights and park lights on both sides flash. Meaning a little bit of voltage is going somewhere it is not supposed to go, not a lack of voltage. If I turn the park or headlights on manually or it is dark out in auto everything works fine.
Expert:  GM Tech (Cam) replied 1 year ago.

Ok, I was thinking it was low voltage. So as it stands now, with the LED's out then its working properly and you have new ones coming?

Customer: replied 1 year ago.
Expert:  GM Tech (Cam) replied 1 year ago.

OK, So is there more I can get you then?

If it works with the LED's out, thats what needs to be fix.

Customer: replied 1 year ago.
Put the replacement parts in and it did not fix it. Then I unplugged every light on the front end at the same time. This would be the high, low, front turn, DRL and corner lights. The rear park lights and license plate lights still flashed with the turn signals.
Customer: replied 1 year ago.
I have a video showing my light issue if that would help.
Expert:  GM Tech (Cam) replied 1 year ago.

Sure, post the link.

Sorry this is a difficult issue you have.

Customer: replied 1 year ago.
URL=http://i197.photobucket.com/albums/aa247/extrabigjon/AG/light%20issues.mp4][IMG]http://i197.photobucket.com/albums/aa247/extrabigjon/AG/th_light%20issues.mp4[/IMG][/URL]
Hope this works
Customer: replied 1 year ago.
http://vid197.photobucket.com/albums/aa247/extrabigjon/AG/light%20issues.mp4
direct link if the above fails
Expert:  GM Tech (Cam) replied 1 year ago.

Got the video. Let me dig and see. I think we need to pink one issue, one light and once we find that, we can find the rest. What I want to chase is the fact the signal lights are on with the parks. I am assuming the park lights off, the signals don't stay on, correct?

Customer: replied 1 year ago.
That is correct.
Expert:  GM Tech (Cam) replied 1 year ago.

Ok, try this exactly as I outline.
"
Remove the fender brace and flip up the underwood fuse block. Disconnect the larger red connector from the fuse block and see what that does for your lights.

Customer: replied 1 year ago.
With the big red plug disconnected the mirrors and dash indicators do not glow while the park lights are on.
Expert:  GM Tech (Cam) replied 1 year ago.

OK that tells me that you have a short in the wiring to the back from that fuse block. That red connector is what takes the power from that fuse block to the rear lights. Some wire back there is shorted to the other. We need to look at every wire, related to lights. Trailer plug, regular lights, even the bundle of wire if present for a 5th wheel plug in the block. This wiring is mounted in behind the box on the front box mount, drivers side.

Customer: replied 1 year ago.
Went and checked the lights again after dark. For some reason my battery is dead now. I have a charger on it and will let it run over night. The battery is from November 2012 when I replaced the original. After the charger ran for a while I have a correction to make. With the red plug removed the mirrors and dash indicators are still dimly lit when the park lights are on. When I have been checking the lights previously I had the truck running. It seems to make the problems more pronounced.
Expert:  GM Tech (Cam) replied 1 year ago.

Ok so red did not change it at all? Ok the connector to the front lights in the fuse block. flat with 2 rows. Disconnect that and try again.

Customer: replied 1 year ago.
With red removed, and the park lights on, some of the mirror lights on each side are partially illuminated. Also both dash turn indicators are dimly lit when the park lights are on. Where is the front light plug? Is it the big green one next to the red?
Expert:  GM Tech (Cam) replied 1 year ago.

its under the fuse block but on the front of the under the block. Its a 12 or 16 pin connector.

Customer: replied 1 year ago.
Removed the plug for the front lights. It was a green one next to and the same size as the red one for the rear lights. With the park lights on, some of the mirror lights on each side are partially illuminated. Also both dash turn indicators are dimly lit when the park lights are on. So no change.
Expert:  GM Tech (Cam) replied 1 year ago.

OK, remove the cluster next and see if that makes it stop.
if not, check the wiring around the under dash fuse block.
WE have this down to inside fuse block issue, underwood fuse block issue, Body Control Module (BCM) or wiring between them.

Customer: replied 1 year ago.
Removed the cluster and the mirror lights were still on.
Expert:  GM Tech (Cam) replied 1 year ago.

SO now it get down to a bad fuse block underhood, bad fuse block under dash, or bad wiring between t hem. Do you have someone with a similar truck you can borrow the fuse block from underhood and test with?

Customer: replied 1 year ago.
I don't have any of those parts available to borrow.
Expert:  GM Tech (Cam) replied 1 year ago.

Ok so I am not sure how to direct you now. I am positive its in one of those devices, the udnerhood fuse block being the more common one due to moisture and such, but then I have see issues on the dash unit with the wiring in behind.

Customer: replied 1 year ago.
I do have an aftermarket remote start system from viper. It was professionally installed in late 2011 and all connections were soldered. Never had any problems with it. If you think this might be an issue I'll get a hold of the installer and see if they can remove or disable it to test. This is the only thing non oem spliced into the truck.
Expert:  GM Tech (Cam) replied 1 year ago.

The problem with remote starters is they don't interact with the signal lights, so that is strange. What I would do is disconnect the modules, expose the wiring connections to make sure they do not short to any other wires and if that does not change anything then its like I was saying, in a fuse block or factory wiring.

Customer: replied 1 year ago.
Just throwing it out there for full disclosure about what is not stock on the truck. I'll get the remote start inspected to rule it out just encase. It might be a bit till I can get back to you with an update on it. Sounds like we will get a decent snow event in the beginning of next week. To get the lights to appear operational I need a load resistor in each front turn signal and manually turn my headlights on every time.
Expert:  GM Tech (Cam) replied 1 year ago.

Understood. Let me know what you find.

Customer: replied 1 year ago.
Got the remote start looked at. You were correct that it does not interface with the signal lights, only the park lights. Everything checked out good and removing it did not fix my lights.
Expert:  GM Tech (Cam) replied 1 year ago.

OK then I am left believing that you have a problem in the fuse block or wiring between them. IF you can get your hands on one to test that would be valuable. Otherwise I am not sure how else to direct you. All circuits front and back work, removing the LED's did not change it so its not interferences between those. The fuse blocks, starting with underhood is the next place.

Customer: replied 1 year ago.
Any chance the multi-function turn signal lever could be involved? We have ruled out the BCM correct? I know that is not a cheap part to replace. Would the underhood fusebox be related to my issues where some of the park and license plate lights flash when I use a turn signal with the headlights and park lights off? Or the turn signal only flashing once?
Expert:  GM Tech (Cam) replied 1 year ago.

The multifunction switch does not have park light feeds going through it.

I believe the Underhood fuse block does have all feeds going through it and it's been know to have lighting issues. The internals are a bussed electrical system that's prone to issues if there is a poor connection inside or corrosion.

Customer: replied 6 months ago.
Cam
I purchased and installed a new under hood fuse block GM part # 15786043. This did not change anything.
Expert:  GM Bob replied 6 months ago.

Hello my name is***** you still need help?

If so I will try my best to help.

I may ask repeat Question the other expert may have asked. Please be patient with me.

Thank you

Customer: replied 6 months ago.
Hi Bob
Yes I'm still looking for help.
Expert:  GM Bob replied 6 months ago.

Thanks for getting back with me.

Just want to be clear with your problem.

All park lights come on Front and Back?

Do they flash or just light up?

This happens with left and right turn signals?

Customer: replied 6 months ago.
The rear park lights and license plate lights flash at about half of normal intensity. Also the front corner 194 park light, opposite of the selected turn signal, barley flickers. Yes the park lights flash with either turn signal. To make the lights appear to work in traffic I manually turn the dash knob to park or headlights during the daytime. I need to drive with my headlights on all the time. There is a nighttime video above here of the lights if that helps.It looks like my issue is when a turn signal is used approximately 3-6 volts is being back feed to the park lights.
Expert:  GM Bob replied 6 months ago.

Sorry just got home.

Have you removed both rear turn bulbs and test the system? if still did it? Have you removed the front turn bulbs?

Expert:  GM Bob replied 6 months ago.

Also try removing each park light fuse.

Customer: replied 6 months ago.
Not sure if I can quote any of the above troubleshooting so I'll copy and paste.
Regarding removing rear turn bulbs:
10 January 2016 09:40
With all four plugs disconnected from the rear junction block and the tow plug in the bumper. The front 194 led on the opposite side as the selected turn signal blinks at normal brightness instead of a faint flicker.
Regarding removing front turn bulbs:
24 January 2016 03:31
Put the replacement parts in and it did not fix it. Then I unplugged every light on the front end at the same time. This would be the high, low, front turn, DRL and corner lights. The rear park lights and license plate lights still flashed with the turn signals.
Expert:  GM Bob replied 6 months ago.

When you said (front 194 led on the opposite side as the selected turn signal blinks at normal brightness instead of a faint flicker.)

So when the passenger turn is on the driver side 194 bulb blinks?

Expert:  GM Bob replied 6 months ago.

This was when you had the junction block unplugged.

Customer: replied 6 months ago.
11 January 2016 10:41
For example, with the headlights off and left turn signal activated. All the proper left turn signal lights blink like they should AND the left rear top 3157 park light, license plate lights, right rear top 3157 and bottom 194 park lights blink. Also the right front 194 led will flicker very faint. The dash indicator and mirrors function correctly. I think a few volts are "bleeding" from the turn signals to the park lights. For traffic behind me it looks like I'm using my hazards instead of turn signals. My temporary fix is just turn the headlights on manually every time.Video of my issues, sorry for the poor quality and slow walk around.
http://vid197.photobucket.com/albums/aa247/extrabigjon/AG/light%20issues.mp4I'm not sure if you are allowed to see the troubleshooting I've done with other techs or not. Is there a way I can send it to you?
Expert:  GM Bob replied 6 months ago.

This video is your truck?

Customer: replied 6 months ago.
it is my truck
Expert:  GM Bob replied 6 months ago.

Have you put back in the stock bulbs?

Just to see what happens.

Expert:  GM Bob replied 6 months ago.

Ok so what I have read that you put stock bulbs back in and they worked properly.

Is that correct?

Expert:  GM Bob replied 6 months ago.

Wow I'm sorry that you have been dealing with this problem from January.

Customer: replied 6 months ago.
Thought I could get buy manually turning on my lights for a while. Then that got old. It took a while to save up for the fuse box. GM was pretty proud of it, but it came preloaded with new fuses though.
Expert:  GM Bob replied 6 months ago.

This problem is only with the LED bulbs?

Customer: replied 6 months ago.
I have tried different led's. If I unplug the front wire harness from the under hood fuse box, green plug, why do the dash indicators and some of the mirror lights illuminate. Same issue with the red plug for the rear light harness.
Customer: replied 6 months ago.
I have a led comparable flasher.
Customer: replied 6 months ago.
I have a led compatible flasher.
Expert:  GM Bob replied 6 months ago.

This problem is only with the LED bulbs?

Have you or can you put stock bulbs back in?

The Lighting system has a voltage feedback problem. This will cause the dash lights to come on.

I have had faulty stock bulbs cause the dash to light up.

Customer: replied 6 months ago.
I installed the led's in stages. The final stage was the four 3157 lights in the tails. That's when my problem appeared. So I put the four 3157 incandescent bulbs back in the tails and the problem did not go away. I have swapped every forward facing bulb with another 2004 silverado all at the same time and that did not fix my issue.
Customer: replied 6 months ago.
The issue is more pronounced with the engine running. I assume this is due to the higher voltage. I think the led's show the back feeding more because the are more sensitive. I think the incandescent bulbs help mask the issue by dissipating the voltage bleed and adding additional resistance. I could be wrong but I still would like things to function properly.
Expert:  GM Bob replied 6 months ago.

Now with stock bulbs. The problem is still there.

I think the LED bulbs my have damage a ground.

Have you tried adding a ground wire to ether tail lamps.

They all use the same ground.

Customer: replied 6 months ago.
I don't think I tried disconnecting the green and red plug at the same time. The fuel pump is in the red plug so I can't start the truck.
Expert:  GM Bob replied 6 months ago.

I'm thinking The rear junction block has lost its ground. Maybe internally.

If you could run a good ground for testing.

Customer: replied 6 months ago.
How would I go about running the temp ground for testing?
Customer: replied 6 months ago.
How about a jumper from the trailer plug ground pin back to the negative battery post?
Expert:  GM Bob replied 6 months ago.

That could work. But it will back feed the junction block. If the block is bad may not help

On each tail lamp there is a black wire going to the turn socket.

If you could strip back the wire cover. You don't need to cut the wire.

Get some wire strip the end a wrap it around the black wire,

The other end of the wire find a good ground on the frame and attache it

Customer: replied 6 months ago.
I was just trying to avoid cutting into the factory wiring.
Expert:  GM Bob replied 6 months ago.

I understand

They do make butt connectors with heat shrink on them. Makes them weather proof.

Expert:  GM Bob replied 6 months ago.

Getting late

Can we pick this up tomorrow.

Customer: replied 6 months ago.
Good call.
Expert:  GM Bob replied 6 months ago.

Good morning.

I had a thought last night.

Have you tried putting the stock flasher back in?

If so did you have the stock bulbs in?

Customer: replied 6 months ago.
I do not have a stock flasher. I modified my original one to prevent hyper flashing.
Link to flasher mod:
http://www.gmfullsize.com/threads/led-turn-signal-bulbs-need-help.252204/#post-4984303Thinking I did the mod incorrectly I installed a LM487 flasher that is compatible with led's. The LM487 still did not fix my issue and had a much more annoying clicking sound. I returned the LM487 and put the modified stock flasher back in. This was done with the led's installed.
Expert:  GM Bob replied 6 months ago.

Have you add a ground yet?

Here is what I want you to do.

At the I/P fuse block pull all 4 turn fuses.

With right or left turn on. Check see how many of the feed terminals of the fuses from the flasher have power.

Expert:  GM Bob replied 6 months ago.

Here is a picture

Customer: replied 6 months ago.
I have not added a ground yet. I have all 4 fuses on the side of the dash pulled. The flasher only clicks once with them pulled. How do I know which side is the feed side?
Expert:  GM Bob replied 6 months ago.

With the test light and the turn signal on.

If you put one fuse in and test the others you removed.

Should be no power on them

Expert:  GM Bob replied 6 months ago.

You could pull the flasher and use a jumper wire.

The flasher has letters at each terminal.

(K) is power.

C D H J are the power out to the fuses.

With your problem I'm trying to come up with some test for you.

Some may work?

Customer: replied 6 months ago.
I was using a multi meter with all the fuses removed at the same time. I think that was why the flasher did not work.
Expert:  GM Bob replied 6 months ago.

Do you have a test light?

Customer: replied 6 months ago.
I have a test light
Customer: replied 6 months ago.
I have a testlight
Expert:  GM Bob replied 6 months ago.

Let me know what your test results are with the test light.

Thanks

Customer: replied 6 months ago.
I'll try to explain my findings. While using the test light. Engine running during testing.
LT TRN fuse in one side of LT TRLR lights up
RT TRN fuse in one side of RT TRLR lights up
LT TRLR fuse in one side of LT TRN lights up
RT TRLR fuse in one side of RT TRN lights up
I used the turn signal that corresponds with the only fuse that was in. Meaning right fuse in I only used the right turn signal. Forgot about flipping the lever to the opposite side turn signal.
Expert:  GM Bob replied 6 months ago.

So you had the right turn fuse in. What lights on the truck were flashing ?

Customer: replied 6 months ago.
If I use a multi meter it shows slight voltage on some additional slots that does not illuminate the test light.
Engine running during testing.
LT TRN fuse in, one side of RT TRLR shows 2.73 volts and one side of RT TRN shows a peak of 0.4 volts
RT TRN fuse in, one side of LT TRLR shows 2.74 volts and one side of LT TRN shows a peak of 0.045 volts
LT TRLR fuse in, one side of RT TRLR shows 2.32 volts
RT TRLR fuse in, one side of LT TRLR shows 2.32 volts
I used the turn signal that corresponds with the only fuse that was in. Meaning right fuse in I only used the right turn signal. Forgot about flipping the lever to the opposite side turn signal.
Customer: replied 6 months ago.
I thought I was checking the power at the fuse slots not what the lights on the truck were doing
Expert:  GM Bob replied 6 months ago.

Sorry

I thought you may look to see if anything changed

Customer: replied 6 months ago.
I had some spare time while it was daylight out. Never even thought to look how the lights might of reacted. My internet is being incredibly slow and frustrating lately. Patience in needed just to load the google home page. So I apologize for the delays.
Expert:  GM Bob replied 6 months ago.

I understand.

I'm also trying to make sense of this

The test light should not have lit for all the fuses

If the right turn fuse was in. Only that fuse and one side of the right trailer fuse

Customer: replied 6 months ago.
34;If the right turn fuse was in. Only that fuse and one side of the right trailer fuse " This is correct, it wasn't until I used the multi meter that I found voltage on some of the other slots. I guess a couple volts is not enough to make my test light glow.
Expert:  GM Bob replied 6 months ago.

I'm getting confused.

When you did the test you said this. So they did not light up?

I'll try to explain my findings. While using the test light. Engine running during testing.
LT TRN fuse in one side of LT TRLR lights up
RT TRN fuse in one side of RT TRLR lights up
LT TRLR fuse in one side of LT TRN lights up
RT TRLR fuse in one side of RT TRN lights up

Customer: replied 6 months ago.
Left turn signal on. With the LT TRN fuse in that fuse lights up and one side of LT TRLR slot lights up
Expert:  GM Bob replied 6 months ago.

Did the the right side do the same thing. No power on the left side turn fuses

Customer: replied 6 months ago.
With the test lite the right did the same thing. It would not lite on the left side.
Expert:  GM Bob replied 6 months ago.

Did you look at the lights on the truck when you had the fuses out?

If you leave out the trailer fuses. What do the lights do?

Customer: replied 6 months ago.
It wasn't until I used my multi meter that I discovered about 2.5 volts on the opposite side. Apparently this voltage is not enough to make my test lite glow. Looks like it's primarily going to the trailer side.These are readings I had before:
13 January 2016 09:45
no lights on left turn on right turn on
under hood
TRL PARK 0.71 3-5 3-5
RR PARK 0.71 3-5 3-5
LR PARK 0.71 3-5 3-5
FRT PARK 0.70 3-5 3-5
INTPARK 0.70 3-5 3-5
STOP LP 14.50 14.40 14.38
left dash
VEH STOP 2.28 2.70 2.70
BRAKE 14.36 14.35 14.35
VEH CHMSL 2.28 2.70 2.70
LTTRLR ST/TURN 2.28 5-11 2.70
RTTRLR ST/TURN 2.28 2.70 5-11
LT TURN 0.05 5-11 0.20-0.45
RT TURN 0.03 0.20-0.45 5-11
Customer: replied 6 months ago.
With both LT TRLR and RT TRLR removed at the same time there is no noticeable change in the lights.
Expert:  GM Bob replied 6 months ago.

I'm going need some time look over your reading .

In the mean time I want you to add a new ground at the turn signal socket.

Getting late have to work in the morning.

I have not given up yet.

Expert:  GM Bob replied 6 months ago.

The trailer wiring is all by its self. There should be no back feed voltage. This is factory trailer wire harnesses?

Is there any wires spliced into it from the rear junction block connectors?

Customer: replied 6 months ago.
Factory tow package and nothing spliced. No break controller. I did swap out the factory RV plug to a hopkins 40955.
Expert:  GM Bob replied 6 months ago.

Can you check the trailer plug for voltage. With all trailer turn and tarler park fuses out.

When you turn signals left and right are on.

There should be 0 volts on the terminals

Customer: replied 6 months ago.
Truck was running and I ran a jumper cable back to the battery post to use as a ground instead of using the trailer plug. Pulled LT TRLR and RT TRLR by dash and TRL PARK under hood. I do not have the battery + fuse installed under the hood. Peak voltage means my meter jumped around and this is the highest value noted.
L R Hazzard signal used
LT 0.03 0.02 0.04 peak voltages
Run 0.07 0.06 0.12 peak voltages
+ 0.03 0.03 0.06 peak voltages
RT 0.04 0.03 0.04 peak voltages
Break 0.06 0.06 0.09 peak voltages
- 0.03 0.03 0.03
Back Up 0.02 0.02 0.04
Expert:  GM Bob replied 6 months ago.

That looks good very little or no voltage.

Lights still acting up?

Now at the fusses you pulled. Check if there is voltage on the other terminals of the fuse.

Make sure the park lights are off. You said before when lights are on problem is gone.

Expert:  GM Bob replied 6 months ago.

You posted this

Do you still have the same readings

If I use a multi meter it shows slight voltage on some additional slots that does not illuminate the test light.Engine running during testing.LT TRN fuse in, one side of RT TRLR shows 2.73 volts and one side of RT TRN shows a peak of 0.4 voltsRT TRN fuse in, one side of LT TRLR shows 2.74 volts and one side of LT TRN shows a peak of 0.045 voltsLT TRLR fuse in, one side of RT TRLR shows 2.32 voltsRT TRLR fuse in, one side of LT TRLR shows 2.32 voltsI used the turn signal that corresponds with the only fuse that was in. Meaning right fuse in I only used the right turn signal. Forgot about flipping the lever to the opposite side turn signa

Customer: replied 6 months ago.
the lights still are acting up with those three fuses pulled. Park lights were off for the above testing. I don't think the problem is really gone with the park lights on. More like it is masked. Meaning rather than 3-5 volts off and on it is covered with a constant 14 volts. Hopefully that makes sense.
Customer: replied 6 months ago.
I'm not sure what you are asking here/
"Now at the fusses you pulled. Check if there is voltage on the other terminals of the fuse."
Expert:  GM Bob replied 6 months ago.

I want you to go back to the trailer fuses.

Tell me what voltage you have there.

One side of the fuse should be the same voltage as what got from the trailer plug

Customer: replied 6 months ago.
Voltages of LT TRLR, RT TRLR and TRL PARK. Should these three all be pulled at the same time or one at a time.
Expert:  GM Bob replied 6 months ago.

Same time

Customer: replied 6 months ago.
Park lights were off. The 2.71 voltage readings was fixed and not flashing like the others. One fuse terminal reading is before the comma and the other side is after.
L R HAZZARD signal used
LT TRLR 0.02,11.75 0.03,2.71 0.05,0.11
RT TRLR 0.03,2.71 0.03,11.51 0.05,11.54
TRL PARK 5.41,0.04 5.43,0.04 5.52,0.11
Expert:  GM Bob replied 6 months ago.

I'm trying to make sense of your results.

What 2,71 voltage reading was fixed?

Customer: replied 6 months ago.
The voltages were not constant because they were flashing. I noted the peak voltage reading as it was flashing because of the turn signal. The reading of 2.71 was constant or steady. At the LT TRLR fuse slot with the right turn signal activated. I have a peak of 0.03 on one side and a steady 2.71 on the other. At the RT TRLR fuse slot with the left turn signal activated. I have a peak of 0.03 on one side and a steady 2.71 on the other.
Expert:  GM Bob replied 6 months ago.

There should not be any voltage on ether side.

Looks like the flasher is feeding the 2.71.

I'm wondering if this is normal. Using LED bulbs the 2.71 is causing them to light up.

I Have a 2003 Tahoe I will check see if there is voltage coming from the flasher

Customer: replied 6 months ago.
On the silverado there was lots of electrical changes from 2002 to 2003 model years. I'm not sure on any tahoe changes.
Expert:  GM Bob replied 6 months ago.

I think the small voltage feed back is making the LED light up.

Can you put it all back to stock? Also a new flasher not modified.

The wire system is the same on 2003.

Customer: replied 6 months ago.
I think you are correct that the voltage feedback is making the lights flash. Finding the voltage feedback and stopping it will be the issue. I will try to barrow a stock flasher from another truck.
Customer: replied 6 months ago.
I put a stock flasher in and noticed no change. The modified flasher did not do anything strange to the donor truck.
Expert:  GM Bob replied 6 months ago.

Did you see if you still had feed back voltage with the donor truck flasher?

Could you see if the donor truck itself had feed back voltage.

Customer: replied 6 months ago.
I did not check any voltages. The symptoms stayed with my truck and did not move to the donor truck. I'm guessing it's not the flasher.
Expert:  GM Bob replied 6 months ago.

I agree that the flasher is not the problem.

When you put the LEDs in did you have to do anything to the wires?

Customer: replied 6 months ago.
The led's were plug and play.
Expert:  GM Bob replied 6 months ago.

Can you put stock bulbs back in?

Customer: replied 6 months ago.
I'll have to order some, not enough on hand to do the whole truck.
Expert:  GM Bob replied 6 months ago.

I want to thank you for your patience.

I very seldom give up on a problem.

Also if you feel that I'm not helping you can ask me to opt out.

Keep me updated

Expert:  GM Bob replied 5 months ago.

Just checking to see how its going.

If you think I was helpful. Please take a moment and rate my sevrice.

Thank you

Customer: replied 5 months ago.
I only had 3 3157 bulbs on hand. I put them all on the right side. The park lights don't flash as bad, but I think it is just masking the voltage bleed issue. The incandescent lights being less sensitive to the voltage. When I plug a trailer in with the hazzards on and park lights off. Some of the park lights on the trailer faintly flicker. I have a few trailers and they all have led lights from the factory.
Expert:  GM Bob replied 5 months ago.

Which park lights flicker? all or just the left side. with the trailer off.

What did the dash indicator do?

Did you also have the donor flasher?

Expert:  GM Bob replied 5 months ago.

Are you still working on your problem?

Customer: replied 5 months ago.
I'm still working on it. I currently have incandescent 194 bulbs in all four side marker lights. Also, I enabled the load resistors on the four 3157 turn signal lights. The park lights and license lights still flash. I noticed both dash indicators are very faintly illuminated when the park/headlights are on. Have to look hard to see them but they are on. I still have the stock, non modified flasher, in the truck. I want to order enough incandescent bulbs to remove all the LED's on the exterior of the truck. I doubt this will fix my issue but might aid in diagnosing it.
Expert:  GM Bob replied 5 months ago.

Putting it all back to stock will help diagnosing it.

Does your outside mirrors still flash?

Expert:  GM Bob replied 4 months ago.

Just checking to how its going?

Customer: replied 3 months ago.
I didn't forget about this. Ordered all new incandescent bulbs for the exterior. The small corner ones were back ordered holding things up. They finally arrived and I installed them last weekend. The truck appears better but, I think this is due to the slower rise time of the incandescent bulbs. I can now use a turn signal without having other lights on in the daytime. This is a welcome improvement.The only issues I can see are when the hazard lights are on during the day. With the hazards on, both license plate lights flash at about 25% brightness. Also, both rear park light filaments, the top bulbs in the taillights. These flash very faintly with the hazards. It's a slight glow like a toaster element. Have to look close to see it. I have not tried hooking a trailer up yet.
Expert:  GM Bob replied 3 months ago.

It sounds like your getting closer to fixing it.

For the rear light that are flashing at 25%. Can you add a ground wire to the license plate bulb wire. Just to see if it helps.

You need to splice into the ground side of the circuit.