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Discussion Starter #1
So im going thru my truck and fixing the electrical issues that are common on these things.
Got the interior working for the most part. It finally starts on first crank radio and cluster working.
My issue is the turn signals
Headlights and dome light.

The right turn light is stuck on. Front back and dash cluster
Left turn signal. Doesnt work at all
Even when the hazard is pressed.
Next.
The hazards turn on when the dome light is in the on position and the doors are opened.
Last.
The headlights now dont work.

Fuses look good.
Grounds all cleaned.

2005 GMC Canyon
3.5L l5 4x4
71k miles.

Any suggestions?
Im guessing a new BCM or clean some corrosion if any.
 

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Good idea on the new thread. On the headlights:
Did they work before? Do the DRLs work? (guys, on the 05s, are the headlights the DRLs, or the marker lights?)
Do the high beams work?
Are you trying to turn on the headlight with the switch, or by covering the sensor?
Silly, but you have tested the bulbs to make sure they are good?

Team ,where are the headlights grounded? And are they powered by the BCM?

You mentioned your CEL is on. What codes is it giving?

Signals is either the multi function switch, or the BCM. Let's learn more, but start looking for a BCM. If you can find the Dorman reman one you are in good shape, but those have been scarce.
 

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All the low power light bulbs (tail, directional, etc) are directly controlled by the BCM. The headlights are controlled by 2 relays that are controlled by the BCM: Relay 54 HDLP turns them on/off, and Relay 47 controls hi/low beam. The headlamps all ground at G105 (the splice pack by the battery), and the multifunction switch grounds at splice pack G106 on the other side of the engine compartment, bolted to the fender.
 

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OK so based on Kens digging we have some more ideas. First, clean the connection for the ground packs in the motor compartment. 1 near the battery and 1 behind the airbox.

Then test what happens when you toggle the hazard switch, as he suggested. Then remove the radio bezel and disconnect the hazard button, just to see what happens. A new switch for that should be super easy to find at a boneyard if its faulty.

Still thinking BCM, but lets finish the free stuff first.
 

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Ken, are you thinking that that something in the hazard switch or connecter is shorted between the dimmer cirquit and the hazard circuit, so when the dimmer circuit is activated, the bcm sees a signal from the hazard wire as well and says, time for flashers?
 

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Ken, are you thinking that that something in the hazard switch or connecter is shorted between the dimmer cirquit and the hazard circuit, so when the dimmer circuit is activated, the bcm sees a signal from the hazard wire as well and says, time for flashers?
Yes...in the absence of a good ground, the switch or a connector may have "good enough" connectivity to ground to trick the BCM hazard circuit.
 

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Discussion Starter #7
The headlights were working prior to me cleaning all ground points. Worked just fine. I cleaned 105 and 106. Battery ground and the 3 under the carpet.
After i cleaned those and added the new battery. The headlights went out. Same turn signal problems occured.
As for the interior everything works besides the dome light + hazard + door issue. Lol
But that occured before i cleaned the grounds.
I dont know that the CEL code is. But thus weekend i will talk to the local mechanic and try to use his reader.
I have a feeling i need to clean the BCM.
I just cant work on the truck during the week due to my work hours.
 

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In another thread going on here recently, another user had bad battery cable connections to the battery - make sure your battery replacement didn't disturb the connectivity between the cables and the battery connectors.
 

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Discussion Starter #13
😅 oh my!...
This appears to be an issue.. lol looks like it went thru a mud pit. Lol
Found a 05 chevy colorado at a wrecking yard. Monday im gonna snag that BCM.
$80
Another option is to get mine reman. What do you guys think?
 

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So you think the cab took on some water based on the BCM and TCCM? Looks like it.
How are you going to manage the new BCM and getting it in sync with the PCM? Is the dealer going to reprogram it for you. I ask because some folks have mentioned that the dealer cannot reprogram a used unit. A reman yes, because the VIN is removed.
 

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Google G7 computers they replace components and may be able to jump that burnt circuit. They test for free any repairs are 225.00.

Got mine back and installed GM had to write new software for my entire truck. Going to get it now and see how it performs. It's been a long process but I have all my original circuit boards and match my truck.
 

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Hey RJS6262. I have pieced some together on your truck over a few threads. Can you please explain what went wrong with your truck. What you tried before sending the BCM out. And exactly what everything G7 did for you on yours. And of course, how it works out. Could they do a VATS delete on the BCM? And why do you have to have it reprogrammed at the dealer? You have a real informative story here, and I would like to get the details and costs in one place.
 
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