[TRILOGY]

when i have my headlights on at night i notice they pulsate/flicker really bad when i am driving, but if i put it in neutral when i am driving it stops ?

it only seems to do it when the truck is in drive.

could this be the alternator ?

dash lights are also doing it. :flame:

btw, it is a 05 silverado 5.3/auto

 

[Denaliano]

http://www.gmfullsize.com/forum/showthread.php?t=50439

I was having an issue with my 4 wheel steer lamp flickering and dimming, along with other dash switches.

Flickering lights in dash/flickering headlights.

Some GM trucks exhibit noticeable flickering dash lights and/or headlights, especially at idle with a heavy load (such as the A/C). For some reason GM chose not to use the external sense source terminal on the alternator to detect modulation in the charging current. The following fix will, in most cases, eliminate the flicker and reduce the charging voltage by about 1/2 volt. GM published this fix in a TSB, PI02010, dated June 29, 2004. I have personally tested this fix on my '02 Silverado 5.3L, but if in doubt as to applicability, please refer to the original GM TSB.

You will need to order one connector, 15306009. I ordered mine from GMPartsDirect (http://www.gmpartsdirect.com). Cost of the connector plus shipping came to about $20.

Disconnect battery!

1. Pop off the plastic piece on the new connector. Remove *all* terminals but terminal D by inserting the end of a small paper clip into the tiny square hole on the alternator side of the plug, and pulling *gently* on the other end. (Don't poke it into the terminal itself; the small square opening is just above the terminal.) If you screw up the terminal, don't despair: You only need one, so you have three more to work with.

2. Crimp or solder a ring terminal on the terminal D pigtail on the new plug.

3. Remove the plastic shield and terminals B & C from the stock connector using the same method. Make sure you note the terminal letter for each wire!

4. Plug terminals B & C into the new connector.

3. Attach the ring terminal onto the battery terminal at the back of the alternator. I believe this one is "live" even with the ignition off, so if you don't disconnect the negative battery cable, be very careful you don't short your wrench to ground.

4. Plug in the new connector, reconnect battery and start the truck.

Official GM TSB

IPC Interior Head Lamps Flicker - kw battery courtesy electrical
fluctuation
generator GMT325 GMT330 GMT800 GMT820 GMT830 intermittent lamp light
#PI02010 - (Jun 29, 2004)
IPC Interior Head Lamps Flicker
..

The following diagnosis might be helpful if the vehicle exhibits the
described symptoms in the 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 CS-130D generator.

Recommendation/Instructions:
Vehicles with the listed condition have been found to have a pulse
width charging modulation that ranges alternately from 2% to 97% duty
cycle. This can be observed by checking terminal f with a fluke meter in the
percent range (hertz button pressed twice) and in AC volts.

In order to correct this condition, install a external sense source through the unused "S" terminal at the generator. The generator four-way connector must be replaced with part number 15306009 in order to gain access to the generator sense terminal, which is terminal position d on the connector. The modification involves supplying battery voltage from the battery stud (B+) on the back of the generator using a 0.5-millimeter wire and a ring connector. Next install the appropriate female terminal on the end of the wire and put it into the terminal d position in the new connector (15306009) and install the connector on the generator. This procedure should only be
used for the condition mentioned; other conditions, such as headlights dimming, will not be corrected by the aforementioned procedure.

..

Please follow this diagnosis process thoroughly and complete each
step. If the condition exhibited is resolved without completing every step, the
remaining steps do not need to be performed. If these steps do not resolve
the condition, please contact GM TAC for further diagnostic assistance.

Models:
(1999-2004 CHEVROLET S-10 PICKUP 2WD) and (1999 - 2004 CHEVROLET S-10 PICKUP 4WD) and (1999 - 2004 GMC SONOMA PICKUP 2WD) and (1999 - 2004 GMC SONOMA PICKUP 4WD) and (1999 - 2004 CHEVROLET BLAZER 2WD) and (1999 - 2004 CHEVROLET BLAZER 4WD ) and ( 1999 - 2004 GMC JIMMY 2WD) and ( 1999 - 2004 GMC JIMMY 4WD ) and (1999 - 2004 GMC ENVOY 4WD) and (1999 - 2004 OLDSMOBILE BRAVADA AWD) and (99-04 All Chevrolet full size trucks and utilities) and (99-04 All GMC full size trucks and utilities) and (99-04 All Cadillac full size utilities)

 

[BowTieChevrolet]

My 2005 Sierra unfortunately just joined this thread! Will the tech fix listed within this thread work on my 2005 as I see the fix is directed to 2004 and before? I've read a lot and viewed youtube on this topic. Replaced my battery within 6 months ago and alternator on 10/20/20 when diodes fried in alternator and replaced it with AC Delco ReMan # 334-2747A alternator right before setting the clocks back so I didn't notice the flickering/pulsing until a few weeks ago driving during darkness. A Facebook comment to a post said that there are known issues with the integrated voltage regulator itself inside the alternator that my eventually cause it to crap out. Please, I'm looking for a superior voltage regulator replacement of a different manufacture's make that doesn't use the same crap as Delco. Please, I appreciate any regulator replacements to use? Thank you very much and good luck!