Right Rear Stop/Turn signal out

bbeshoner · July 12, 2014

My right rear turn signal is out. I bought my wife a 2007 Escalade ESV. Nice truck but OMG its got some electrical gremlins. I've been scouring the internet for some wiring diagrams and actually did find some good stuff on gmupfitter.com. Anyway, I'm getting power to the RT Turn/Stop fuse in the I/C fusebox on the left side of the dash. I assume this means my BCM is working. However, the D-GN wire at the Rt. Rear tail lamp is not getting power. Looking for some information on where that wire runs from the fuse box back to the lamp harness. It would appear that the wire runs behind the spare tire to the drivers side and then into the cabin and along the door rail under the plastic thresholds. Is the wire the same color all the way to the front? is there any connectors between the front I/C fuse box and the rear lamp assembly that should be checked?

Looking for any thoughts or wire schematics that would help me trace this wire back to hopefully discover a break or something like that. Getting tired and weak but want to stay away from the dealer as I think they will have to search just like me.

Thanks for any help that you might have...

02suburbanZ71 · July 19, 2014

Let me see.... I think i can help

02suburbanZ71 · July 19, 2014

let us know what the problem is

esv 2.pdf

esv 4.pdf

esv3.pdf

esv 2.pdf

esv 4.pdf

esv3.pdf

bbeshoner · July 20, 2014

I appreciate the diagrams. I'm out of town for the weekend and will have another look next week. Since my last post, I've found what I believe is the BCM output for the right and left rear turn/ stop. Connector 5 at the BCM. When I test the yellow wire out of conn 5, (left), I show power out when I turn on the left signal and when I push the brake pedal. When I test the D-Gn wire, right, I don't show any power out when I turn on the right signal or push the brakes. This would lead me to believe that the BCM is bad but not sure. My understanding is the BCM is the power source for these rear lamps. The fact that the front right signal and left rear stop light are activating would suggest to me that the BCM is getting the appropriate ground signal for both right signal and brakes. I thought about disconnecting Connector 5 and putting some dielectric grease and/or freezing the BCM to see if it might be a cracked weld/cold weld in the BCM. Also will check the right front lamps fuse in the underhood fuse box. I'm getting closer to throwing in the towel. I will also confirm that the I/c right stop turn fuse is really getting power like I thought as the diagrams provided would suggest that the power would be coming from the BCM I think. If anyone can help me think through this, I'd appreciate any insight.

bbeshoner · July 20, 2014

Based on the diagrams sent and some additional diagrams i found on gmuplifters.com, I think my next step is to 1. Verify power at the RT rear/stop turn fuse in the LBEC box. Step 2. Verify power for the RT rear/stop coming from the LBEC box to the BCM at connector 4-3. I do not have power out of the BCM at connector 5 on the BCM so the line in at C4-3 is my prime suspect at this point. I guess if power is going into the BCM at C4-3 and not coming out at C5 then the BCM becomes suspect. Does this seem logical? Is there any reset procedures for the BCM?

02suburbanZ71 · July 21, 2014

To reset the bcm i believe you must go the dealer and pay 95$ for a tech 2

bbeshoner · July 22, 2014

Bad news, there is power at the fuse and power into the BCM at connector 4 pin 3. I now suspect a bad BCM. Now that I have everything laid out, I'll probably go back through it again. Something I read stated that the BCM output to the turn signal will shut down if it senses resistance outside of tolerance or above a certain amount. I'm not sure what that means or how that works but now I'm more interested since the BCM output is now the only thing not working as expected. I will keep posting my progress.

bbeshoner · July 23, 2014

Update....I disconnected the negative battery cable and then attempted to access the bottom side of the underhood fuse box (UBEC). The power from the BCM passes through the UBEC to the tail lamp. I read that the BCM will "restore" the power to the lamp once the problem is fixed, assuming is a short to ground or something. I couldn't seem to get enough wire slack to fully seperate the fuse panel and access the underside but it did seperate several inches. I reset the fuse panel and reconnected the negative battery cable. The right rear turn signal and brake light was suddenly working. Less than 5 minutes and it stopped working. Maybe my BCM is OK. Maybe there's a short in the UBEC. Can't seem to access the underside of that fuse panel. I may try again this weekend.

02suburbanZ71 · July 23, 2014

Update....I disconnected the negative battery cable and then attempted to access the bottom side of the underhood fuse box (UBEC). The power from the BCM passes through the UBEC to the tail lamp. I read that the BCM will "restore" the power to the lamp once the problem is fixed, assuming is a short to ground or something. I couldn't seem to get enough wire slack to fully seperate the fuse panel and access the underside but it did seperate several inches. I reset the fuse panel and reconnected the negative battery cable. The right rear turn signal and brake light was suddenly working. Less than 5 minutes and it stopped working. Maybe my BCM is OK. Maybe there's a short in the UBEC. Can't seem to access the underside of that fuse panel. I may try again this weekend.

I hate electrical issues more than anything because its so hard to find the source. Good luck and let us know

gmtech4 · July 24, 2014

you're barking up the right tree,,,,,how ever ,,,,the new BCM needs to be programmed at a dealer ,,,

having said that if you just go in and say replace and program my BCM and it DOESNT fix it ,,,,you are on the hook ,,,

if you go in and say "my bla bla doesnt work " and it doesnt fix it ,,,its ON THEM !!

something to concider is all

bbeshoner · July 24, 2014

Very true. Pay me now or pay me later right. I'm planning to see if I can verify connectivity from the UBEC out back to the taillight and from the BCM out to the UBEC in. I'm kinda suspecting an open wire with intermittent short to ground . More to look at before I conclude on this one. Might have a problem in the UBEC where the wire appears to pass through but there doesn't seem to be a related fuse in the UBEC other than the trailer wiring and that fuse is OK.

bbeshoner · July 26, 2014

FOUND IT.....I think. Just before the wire harness goes into the UBEC from the firewall, there is a group of wires that leave the plastic wire harness protector and go into the UBEC fusebox, I can't see them but their resting with pressure on a metal bracket. When I pull up on the wires, the turn signal and brake light work, when I push down, the fuse blows. I stuffed a piece of foam rubber between the wires and the bracket to keep them off the bracket. I'll let you know after it's been road tested for a few days. If it stays on, I may just leave it for awhile.

clf2427 · July 29, 2014

FOUND IT.....I think. Just before the wire harness goes into the UBEC from the firewall, there is a group of wires that leave the plastic wire harness protector and go into the UBEC fusebox, I can't see them but their resting with pressure on a metal bracket. When I pull up on the wires, the turn signal and brake light work, when I push down, the fuse blows. I stuffed a piece of foam rubber between the wires and the bracket to keep them off the bracket. I'll let you know after it's been road tested for a few days. If it stays on, I may just leave it for awhile.[/quot

I have a 08 avalanche that right rear taillight is out..where is the box located under the truck?

bbeshoner · July 30, 2014

The UBEC is the underhood fuse box. Located on the driver's side of the engine compartment. There is a black cover over it and mine is against the right quarter panel just above the wheel well.