QuestionQUESTION: My 2002 Chevy suburban's headlights keep dimming really low then coming back on normal for a few seconds to a couple of minutes. Charging system has checked out fine. Fuses are all good. Wires have no corrosion and are tight.Can you give me some suggestions?
ANSWER: Generally when someone has this type of concern it is alternator related!? The GM minivans were particularily bad for this, a recall was issued and ground screws were added to the alternator to correct the headlight dimming issue. However, If you have had your charging system tested, it would seem you have something that is putting a large load on your system intermittently causing your headlights to dim. The only other possiblility is that your headlights are fading in and out of Daytime Running Lights (DRL) mode, I have seen this before, I imagine you are noticing this mostly at night though?? Make sure the ambient light sensor (if equipped with DRL)isn't partially covered or blocked. Aside from that, I don't want to lead you down the wrong path. I personally would be looking really hard at the alternator, maybe swapping it with another known good one for a day and trying it, if you have access to one.
Hope this helps.
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QUESTION: Do you happen to know where the ambient light sensor is located? Looked in the book and was unable to find it. Thank you.
AnswerThe ambient light sensor is located on top of the dash in the centre. It looks like a small dark colored dome.
However, I did come across this researching your case further. It may apply.....
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)
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.
Disconnect the negative battery cable from the battery/batteries.
Slide the protective boot on the generator BAT terminal aside and remove the retainer and wire cable from the BAT terminal.
Unplug the generator 4-cavity terminal from the top of the generator.
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.
Remove and save the orange Weatherpack seal and CPA from the 4-way connector.
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.
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.
Install the gray (Circuit 23) wire of the vehicle wiring harness into cavity "C" of the new 4-way connector.
Obtain a piece of 0.80 mm/18GA black wire, 254 mm (8 in) long.
Install a red terminal seal, P/N 12048086, and terminal, P/N 12048074, (crimp and solder) on one end of the new black wire.
Install the new black wire into cavity "D" of the new 4-way connector.
Reinstall the connector seal and CPA, from the original connector, to the new connector.
Plug the 4-way connector into the generator.
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.
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.
Place the generator output wire and the new black wire onto the generator BAT terminal and install the retainer.
Connect the negative battery cable.
