Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
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What you definitely have is a bad ground.
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.
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
I am out of ideas. I am going to opt out and see if someone else can help
Hi there, I might have some ideas? You said you have an LED in there somewhere?
Ok, if you disconnect the rear junction block, does this still happen?
Let me review this and get back to you. It may be morning.
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?
Yes, blue plug.
Dark green and yellow are signals, light blue is brake and tan and tan black are park lights.
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?
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?
Try a new ground from each front signal light as a test next please.
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?
Are these resistance, I was looking for voltage on the 20V scale.
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?
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.
So if I am reading this correct, only the stop lamps and brakes fuse did you get full voltage on.
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. .
Leave each item unplugged and test the lights in each case, then plug back in and move on to the next.
Am I understanding that with the 194's out of the front it was better?
Did all issues stop with the 194's out?
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.
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.
Ok, testing power supply with the test light at the relay, as bright as testing the battery?
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?
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?
OK, So is there more I can get you then?
If it works with the LED's out, thats what needs to be fix.
Sure, post the link.
Sorry this is a difficult issue you have.
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?
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.
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.
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.
its under the fuse block but on the front of the under the block. Its a 12 or 16 pin connector.
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.
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?
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.
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.
Understood. Let me know what you find.
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.
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.
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.
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?
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?
Also try removing each park light fuse.
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?
This was when you had the junction block unplugged.
This video is your truck?
Have you put back in the stock bulbs?
Just to see what happens.
Ok so what I have read that you put stock bulbs back in and they worked properly.
Is that correct?
Wow I'm sorry that you have been dealing with this problem from January.
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.
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.
I'm thinking The rear junction block has lost its ground. Maybe internally.
If you could run a good ground for testing.
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
They do make butt connectors with heat shrink on them. Makes them weather proof.
Can we pick this up tomorrow.
I had a thought last night.
Have you tried putting the stock flasher back in?
If so did you have the stock bulbs in?
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.
Here is a picture
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
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?
Do you have a test light?
Let me know what your test results are with the test light.
So you had the right turn fuse in. What lights on the truck were flashing ?
I thought you may look to see if anything changed
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
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 upRT TRN fuse in one side of RT TRLR lights upLT TRLR fuse in one side of LT TRN lights upRT TRLR fuse in one side of RT TRN lights up
Did the the right side do the same thing. No power on the left side turn fuses
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?
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.
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?
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
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.
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
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
I'm trying to make sense of your results.
What 2,71 voltage reading was fixed?
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
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.
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.
I agree that the flasher is not the problem.
When you put the LEDs in did you have to do anything to the wires?
Can you put stock bulbs back in?
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
Just checking to see how its going.
If you think I was helpful. Please take a moment and rate my sevrice.
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?
Are you still working on your problem?
Putting it all back to stock will help diagnosing it.
Does your outside mirrors still flash?
Just checking to how its going?
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.