T.Sickles

Does anyone know where I can find the +12v reverse illumination wire in a '09 LTZ 'Burban w/4WD under the dash area?

I am installing towing mirrors and I want the 'rear guidance lamps' on the towing mirrors tied into the reverse lamps (so that they illuminate BOTH when the unlock is pressed on the key fob to act as courtesy lights and when the shifter is placed into reverse to help illuminate behind the vehicle in reverse).

​​​​​​I cannot use the radio's rear view camera power because that runs off the CANBUS decoder (plus it won't send power when unlock on the fob is pressed anyway). I realistically need the direct power wire trigger to the reverse bulb on the tails, but I don't feel like tapping into the reverse way in the back and running a new wire all the way forward.

I cannot find any pin diagrams for my specific vehicle, and the videos I have found out there do not work/apply to my truck.

mountainmanjoe

charm.li or gmupfitter.com

T.Sickles

Thanks for the links, but the GMUpfitters diagram is wrong for my model year. I think I need to locate one specific to my actual vehicle due to variations even between GMT900's.

Here's the diagram it shows for the BCM (X5 connector {brown}, Pin #11, Dark-Brown Wire):





Now here is my Brown X5 BCM connector and Pin #11. Wire #11 on mine is yellow, not dark-brown like the diagram says it is:




Farther proof the diagram is incorrect, look at this dark-blue wire on my connector. That dark blue wire is Pin #7. According to the wiring diagram above, Pin #7 is unused.... so clearly the diagrams are incorrect for my vehicle. I also probed every single pinout on the BCM X5 connector and not a single one reacted in sync with the reverse lights when triggered.

mountainmanjoe

I definitely wouldn't be molesting or piggybacking my BCM circuits. I'd run a new power wire back to the fuse panel and then switch it with a relay energized by the circuit #24 signal.

T.Sickles

​​​​​​Will be using it for a relay trigger that is fused, not a main power source, on low voltage LEDs...just as it was designed. I'm trying to keep the install as clean and OEM looking as possible, hence don't want to mess with tapping into the relay on the fuse block PCB and feeding into the cabin.
​​

mountainmanjoe

the 2011 electrical manual might be closer to your vehicle's layout
https://www.gmupfitter.com/wp-conten...abs_100813.pdf
and pay particular attention to page A-13

The other link I gave you (charm.li) will definitely have schematics for your exact year.

a55bruce

Try X2 pin 22 for the BCM signal to the reverse lamp relay.
2009 Burb Backup Lamp Schematic
Good luck

mountainmanjoe

Looks like there's already a provision for reverse signal. You could just tie into "Junction Block - Left instrument panel" on circuit #28.

If you want to go the safe route and not risk frying your expensive BCM, there's a nice fused circuit (#24) right there (Fuse 15 VEH BCK/UP)

I have no idea how you're going to tie in the keyless remote though.



w

T.Sickles

That was it!
​​​​​​
Thank you so much for your help, everyone.

BCM commands the relay regardless of whether it's shifted into reverse or keyless entry asks for lighting.

mountainmanjoe

there's already a relay on x2:22
if you put one in series, you may not get enough voltage to operate either of them. If you put one in parallel, you may overload the circuit. You also need to protect against voltage spikes from relays per the technical bulletin I mentioned. just FYI.