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2001 1500HD DRL and AHL issues

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I have an 01 1500HD with about 110k on it. I have owned it for 1.5yrs and when I first got it the DRLs and auto headlights worked properly. A while back I started having the headlights turn on evertime I started the truck (day or night) and have to do the dome override all the time.


I have done a ton of searching/reading and done the following:


I changed DRL bulbs - nothing.

Sockets looked burned so I changed them - nothing.

Checked fuses and swapped relays - nothing.

Put a new ambient light sensor in - nothing.

Finally tried a new headlight switch - still nothing.

Pulled the BCM to see if there were any cracked solder joints or anything looked burned - nothing.

Tried cleaning ground points and ran a few redundant ground lines for battery/body/frame - nothing.


Codes from the BCM are:








I dont seem to have any other weird electrical issues that would lead me to believe the BCM is bad.... Does the Ambient light sensor route thru the BCM and headlight switch only or does it go thru the HVAC controls as well?


Any other ideas? I would like to avoid paying to have it fixed if I can do it myself, but I am at a loss.



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Another question...anyone have a pic of the ground point under the dash on the drivers side? G203 possibly?

When I had the dash cover off I found the ground point on the passenger side with two smaller wires. Cleaned up that connection with no change.

Looking on the drivers side I could not find anything that looked like a ground connection under the dadh cover. Checked behind the light switch/AC vent and even behind the kick panel near the floor...nothing.

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Passenger space for this gen has 4 ground points. 200 series are the dash area, 300 series are seating space, 400-800 and higher are doors and farther back.

FSM shows two dash points. Either end, bolt faces up, on rail, near the A pillar.

Two body points. One under the driver seat for use the power seat circuit. The other is on the driver B pillar some 6-8 inches up (older GM's had this hidden under the door/floor trim)

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Thanks...is there a diagram by chance? When I had the dash cover off, the one on the passenger side at the base of the A pillar was easy to find. I looked pretty extensively on the driver side and couldnt find a stud or anything that looked like a ground point with anything attached.

Is the one at the bottom of the B pillar just for the seats?

Thanks in advance!

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Per FSM, the dash ground points are located on the upper support rails for the dash. It's a upward facing bolt.

The two dash ground pretty much split the dash and door grounds

B Pillar covers the rear doors and beacon lights on pickups

The ground under the driver seat covers the seats

(Generally speaking)

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Found it. Down a little deeper than I was looking the first time. Cleaned it up and still no change. Guess I will have to take it some where for a diagnosis.

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