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2013 Sil 2500HD No DRL/AHL


CoRifleman

Question

Going to cross post this in hopes I can square this away.

 

Just bought a fleet 2013 Silverado 2500HD.  When I first got it, the ambient light sensor cover was broken off, ie sensor exposed.

 

Neither the DRL or AHL seem to work.

 

I can manually turn on the headlamps and they work fine.

 

The truck does NOT have RPO T61 (DRL), but also does NOT have RPO T62 (DRL Delete).  It DOES have RPO T74 (Auto Headlamp / Delay).

 

I've replaced the ambient light sensor with the new GM part number (the original number was superceded).

 

Troubleshooting:

 

I verified that if I ground BCM connector X4 (Black), pin 23 (l-gn/bk), the DRLs come on.  Which means all wiring in the fuse box, the on board pcb relay, and wiring to the fuse box are good.  To me, that leaves the inputs needed to energize the relay in the BCM (ambient sensor, in-gear, no ebrake) or the BCM programming.

 

As best I can tell, the gear selector and ebrake trigger/sensors work correctly.

 

Regarding the AHL, I went to the headlamp switch and verified that the L-BU (parking), D-Gn (OFF), and WH (Headlamp) lines all rest at 12v and drop to 0 when the switch is on their position.

 

Any ideas?

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Not to be a smart ass, but, I think you have found out why that ambient light sensor cover was missing.  Have you gone through the various settings in the DIC regarding light operation?  I don't get why anyone would ever order a vehicle with DRL not installed, or nor operational.

Have you checked all the fuses in all the fuse panels?  Why GM didn't put them all in one location, under the hood is beyond me.  Its not like there is a shortage of space.

 

Make sure that you are checking voltages with all connections in place, an open connection will display battery voltage when tested with a voltmeter.  Can you get access to a BCM scan tool?  I have never used one, but would love to get my hands on one just to see what it can and cannot do.

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5 hours ago, Doug_Scott said:

Not to be a smart ass, but, I think you have found out why that ambient light sensor cover was missing.  Have you gone through the various settings in the DIC regarding light operation?  I don't get why anyone would ever order a vehicle with DRL not installed, or nor operational.

Have you checked all the fuses in all the fuse panels?  Why GM didn't put them all in one location, under the hood is beyond me.  Its not like there is a shortage of space.

 

Make sure that you are checking voltages with all connections in place, an open connection will display battery voltage when tested with a voltmeter.  Can you get access to a BCM scan tool?  I have never used one, but would love to get my hands on one just to see what it can and cannot do.

Ha, yeah you're probably right, not knowing why it wasn't working, the last guy probably broke the cover off thinking it was a sensitivity problem.... but even with a light shining directly on it, there's no activity (although I used an led light, and I'm not sure those trigger sensors - and at night there is no activity at all).

 

Nothing in the DIC is about the DRL or autolamps, just approach and exit lighting.

 

I've checked the obvious fuses that tie into this circuit, but I guess I could go through 1 by 1 and see if something strange is popped.

 

Doors lock and unlock with the truck being put into gear, so I know the correct "gear" command is being seen by the BCM.  The Ebrake indicator lights up on the dash, I so I am "assuming" the BCM is getting that input as well.

 

And yes, my tests were done with the light switch installed - I was able to change its position and get different wires to show ground (correctly).  I had read that if you ground that D-GN wire off the headlamp switch that it gives a off signal to the bcm and the auto lamps don't come on - I made sure there's no continuity to ground on that lead, in case someone had tried that, but it doesn't show any connection to ground when the lamps are set to "auto".

 

I've got a scanner that can do quite a bit, but definitely not dealer level BCM stuff.  I don't even know if you can get those on the "private" market without shelling out for a Tech2 or something insane.

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Want to follow up for anyone else who has this issue.  I tested both the BCM out and BCM in for the DRL and found that if I manually triggered the DRLs on the BCM out side, the fuse box would act correctly and fire them up, meaning it had to be in the bcm.  I also verified that the ambient light sensor was performing correctly.

 

I contacted a local dealer about an appointment to have the programming of the BCM reviewed.  Shortly after the truck was built, the BCM was reflashed with a program that disabled the DRLs and Auto Headlamps (AHL).  The dealer had to contact GM and have a new software built and sent to them.  Then they flashed the new software onto the trucks BCM.  That fixed the issue.

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Thanks for the follow up.  Really have to wonder why anyone would disable DRL.  Did the dealer see in the repair history that that was done?  I know in Canada it is unlawful to disable DRLs on any road-going vehicle that came equipped with DRL from factory after a certain year.  I think it was a year or two from the high mount 3rd brake light. We have had them here a few years prior to the USA.  Did they perform the reflash for free?  If not, you may want check into the local laws regarding the sale of used vehicles with safety devices disabled.  I know here that from about 1990 it became part of the required safety check that all used vehicles had to pass in order to get license plates.  And about 5 years ago they bumped up the penalties to include the mechanic that signed the safety check knowing that the vehicle did not pass the inspection. 

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