my 02 sierra did not come with fog lights.....i installed some but they don't seem to work?.......i bought the switch from the dealership that is the cargo and fog switch...... also a whole wiring harness that ended in a green box that is under the fuses.....and the fog lights are denali oem fogs......all seemed straight forward.....but no love......so i thought maybe allen has to do something to my pcm to make them work........ but no......is it the bcm?......or what?.......can somebody give me some advice please?

 

Yeah, you're on track with the pcm. I believe you need to have your dealer program the pcm for the factory fogs.

 

You need a relay too.

 

My nephew had the same problem. go to the dealer and they will program the bcm for them.

 

It's actually the BCM that needs programming.

 

I'm having problems with my foglights, my truck came stock with them and they dont work, i took it to the dealer and they hooked it up and said it was programmed in the BCM, and then he used his Tech II to turn them on and it worked, but the switch will not turn it on. I've replaced the Relay,Switch, and had it reprogrammed with no luck, any suggestions?

 

so i'm gathering it is in the bcm......and the stealership has to touch my truck?....scary..........o.k.....will it effect my allen tune?......they know i have it tuned and don't seem to care........but the last thing i want is them to mess up my tune.........it seems that they wouldn't come near the pcm.....but i also thought fog lights how tricky can they be...........damnit.

 

bcm and pcm are different all gms are set up like this...same **** has to be done to a malibu.....you could switch for a wrecked bcm with fog lights but your odomoter may be off. its like 40 bucks to get it done at a dealer

 

check your harness for shorts or anything unplugged fuses bulbs etc if thats all good go to another dealer have them check the bcm......if the bcm is screwed up may need to replace it or reprogram it

 

the thing is they can turn the lights on with the tech II so i dont think its the harness or anything i dont really know what to do