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Mark
Mark, ASE Certified Technician
Category: Chevy
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Experience:  34+ yrs Dealership Exp. - Fully State & ASE Certified - GM Master & GM World Class Tech
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Chevrolet Silverado 1500 2001 Silverado pick up. Lights dim

Resolved Question:

2001 Silverado pick up. Lights dim and flicker at night. Alternator gauge reads about 14.5. I put in new battery didn't change anything. Air bag light comes on, gauge is pegged out and lights get bright and go dim. I have a boss snowplow installed by a professional. I had Chevy look at it and the said they put an upgrade on the wiring but nothing has changed. I cannot see well at night with the dim lights. What can be done to correct this. It has always been a problem to an extent but has gotten worse over time.
Submitted: 3 years ago.
Category: Chevy
Expert:  Mark replied 3 years ago.
Greetings, my name is Mark.

I found the bulletin that the chevy dealer most likely used when you mentioned they updated the "wiring". I was confused by that. I have included it below for your reading to confirm that they did do what this bulletin is "suggesting".

I too am only "suggesting" and telling you right up front, I do not have a concrete answer for you on your issue. Reading and re-reading your post, it really does sound like you have more than one concern, and I am wondering if they are related.

First of all, your lights shouldn't "flicker or dim". That is not a "user" preference or some made up problem. If your lights truly do "flicker or dim" and you can see that at night, then there is something going on. And my suggestion here is replace the Alternator. Even though you have had it checked out, even though your gauge is reading what it is, you still should at least start there. That is the factory of the electrical system and you have nothing to lose by replacing it. Your truck is 10 years old and you have a plow system hooked up. There is no doubt the alternator has been used extensively. Even if you feel this issue has been present for a long time, what have you got to loose?

AND, I wouldn't go aftermarket on the alternator. Step up to the window and get a genuine GM Alternator. This is something you can install yourself. Save the money on the labor. But use a genuine GM.

You second issue with the lights not being as bright and you're having trouble seeing, I cannot tell you the alternator is going to fix that. I am not sure this is a actual problem or a user preference. I have 3 vehicles of my own, and only one gives enough light to see safely. It is a user preference. The alternator may or may not be related.

Again, this is only a suggestion. I am only passing on what I would do if it were my vehicle. I hope the best for you and I hope you can get this resolved.


#PIT3170E: IPC, Interior Lights and/or Headlamps Flicker - keywords battery courtesy electrical fluctuation generator head intermittent lamp light - (Jan 11, 2006)
Subject:IPC, Interior Lights and/or Headlamps Flicker
Models:1999-2005 All Cadillac Full Size Utilities
1999-2005 All Chevrolet Full Size Trucks and Utilities
1999-2004 Chevrolet Blazer, S-10
1999-2005 All GMC Full Size Trucks and Utilities
1999-2004 GMC Envoy Classic, Jimmy, Sonoma
1999-2001 Oldsmobile Bravada
Without Regulated Voltage Control


The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:

Customers may have comments of a flickering light condition in the IPC, interior lamps or headlights. This condition is most likely to be noticed when the engine RPM is low and when high electrical load requirements are in place on the generator.

Recommendation / Instructions:

Important: Review bulletin 02-06-03-008A - Low Voltage Display on IP Gauge, Lights Dim at Stop Lights, Battery Discharged, before proceeding with this PI.

  1. Disconnect the negative battery cable from the battery/batteries.
  2. Slide the protective boot on the generator BAT terminal aside and remove the retainer and wire cable from the BAT terminal.
  3. Unplug the generator 4-cavity terminal from the top of the generator.
  4. Inspect cavity D on the generator connector for a red cavity plug. If a red cavity plug is present, it is not necessary to replace the generator connector. Remove the CPA and save. Remove the red cavity plug and continue with step 9. If a red cavity plug is NOT present, continue with the next step.
  5. Remove and save the orange Weatherpack seal and CPA from the 4-way connector.
  6. Using the proper terminal removal tool, remove the two or three wires from the 4-way connector. On vehicles without Supplemental Brake Assist (SBA), install a red cavity plug, P/N 12059168, into cavity "A" of the new 4-way connector, P/N 12186568. On some 2003 and 2004 model year vehicles with SBA, install the dark blue (Circuit 5668) wire of the vehicle wiring harness into cavity "A" of the new 4-way connector.
  7. Depending on the vehicles model and year, install the brown wire (Circuit 25) or red wire (Circuit 225) of the vehicles wiring harness into cavity "B" of the new 4-way connector.
  8. Install the gray (Circuit 23) wire of the vehicle wiring harness into cavity "C" of the new 4-way connector.
  9. Obtain a piece of 0.80 mm/18GA black wire, 254 mm (8 in) long.
  10. Install a red terminal seal, P/N 12048086, and terminal, P/N 12048074, (crimp and solder) on one end of the new black wire.
  11. Install the new black wire into cavity "D" of the new 4-way connector.
  12. Reinstall the connector seal and CPA, from the original connector, to the new connector.
  13. Plug the 4-way connector into the generator.
  14. Route the black wire to the generator BAT terminal, sliding the wire into the small end to the output terminal boot, along side the generator output wire.
  15. Obtain a ring terminal from the terminal kit (J-38125-D) that is the same diameter as the positive post of the generator. Crimp and solder the ring terminal from the terminal kit (J-38125-D) on to the open end of the new black wire.
  16. Place the generator output wire and the new black wire onto the generator BAT terminal and install the retainer.
  17. Connect the negative battery cable.
Customer: replied 3 years ago.
Thanks for your honest reply. I have a friend that works at Chevy in Oswego and I will give him this info. The problem really is the lights are too dim. Almost like they are not even on some times (exaggeration). It seems to be the reverse of what one would expect in the old days. More prevallent with higher RPMs than lower. Rnning along normal speed or slightly slower the headlamps are just annoyingly dim. Driving for some time at a high speed (over 65) seemed to exacerbate the problem - almost like the system was building up energy and releasing it. The lights do get bright briefly after this so-called release and then go back to dim. One side is just dim and the other flickers. I also noticed when rolling down the window they get really dim and go back to "normal" when the button is released. I held the button down after the window was all the way down and they went almost all the way out, the airbag indicator came on, the volt/amp gage pegged out. The reason I got a new battery was because it let me down on top of a hill out hunting. Battery completely dead. Just for you info - if there is anything else I should do you can follow up.
Thanks.
Expert:  Mark replied 3 years ago.
Thanks for you reply and good for you with a friend at the dealership.

You don't have to click the ACCEPT as I am just giving you my two cents here. Another thing, and you're friend should agree, you need to make sure all your ground circuits are intact. There is probably nothing more important short of a component failure.

You most likely have, and if you took it to a dealership to have the wiring repaired, they probably looked over the existing wiring, but the grounds are extremely important.

There should be the ground coming from the battery down to the passenger's side cylinder head or engine block. (I think) Then back by the master cylinder, you should see a braided ground strap from the body to the back side of the engine.

Even if these are there, you should take everything apart and clean thoroughly. I don't like what you're telling me on the lights dimming with a load on the system. Again, the alternator is either not doing it job or you have a ground issue.

Below I have included the grounds for your truck. Some are diesel or other engines, but you can sort out what applies to your truck. You friend has access to this info also.

--

G100

On the left front body mount

--

G102 (Diesel)

On the right front of engine block in front of starter

--

G103

On the left rear of the engine block

--

G104 (Gas)

On the left rear of the engine block

--

G104 (Diesel)

Lower left side of the engine block just behind the oil pressure switch

--

G105 (4.3L)

On the right front of the engine block, Battery Gnd.

--

G105 (4.8L, 5.3L, 6.0L)

On the left side of the engine block, just below the second bank exhaust

--

G105 (8.1L)

On the left front of the engine block

--

G106

On the right front of engine (6.6L Diesel)

--

G107

Engine ground strap

--

G110

On the left front body mount

--

G200

On the right upper I/P at the A pillar

--

G203

On the left upper I/P at the A pillar

--

G302

On the left body mount

--

G304

Under the driver seat

--

G304

Under the driver seat

--

G305

Inside the passenger compartment on the left side at the B pillar

--

G306

Inside the passenger compartment on the right side at the B pillar

--

G401

On the spare tire hoist bracket

--

G403

On the left frame body mount bracket

--

G410

On the right rear inner side body panel



Good luck to ya.........and if you want to keep me informed as to what you find (if anything) I would appreciate.

Take care..........
Mark
Mark, ASE Certified Technician
Category: Chevy
Satisfied Customers: 840
Experience: 34+ yrs Dealership Exp. - Fully State & ASE Certified - GM Master & GM World Class Tech
Mark and 11 other Chevy Specialists are ready to help you

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