Hi all, new to the forum. We have a 2004 Cayenne base 3.2L. It was purchased from the dealer as a demo in 2004 so it has been in the family almost since new. It currently has 109k miles on it, so pretty low considering the age.

We have an issue where the left turn indicator does not work. This includes the front, rear, and when using the hazards. Absolutely no left indicators on the Cayenne. We have replaced bulbs, swapped the front bulb sockets, patched frayed insulation on the front mini wiring harnesses, swapped the harnesses left to right, inspected inside the headlights, inspected the rear tail light harness/wiring, replaced all fuses even if they looked fine.

Here's the odd part. If we trailer our camper the camper indicators work! The Cayenne's indicators still won't work but anything connected to the 7-pin trailer connector does.

We were told the BCM could be the issue. To me if the trailer lights work the turn signal lever works and possibly even the BCM. Is there a way to test the BCM?

Any suggestions are welcomed.

 

has to be wiring at the assemblies if the trailer connection for the left works. Cannot be the turn signal lever if the hazards are not working as well. Need to go back to the wiring and find the wire for each front and rear turn signal and then check the ground lead

 

I had to remove the harness front plug from its seat, and connect it directly to the headlight to get my turn indicator back.

Somehow the light is able to slide back in with no problem, and that's good enough for now.

 

Thanks for the replies. I have tried plugging the harness in directly, not in the seat. and that has not worked. I removed the headlight tray to inspect all of the wiring and luckily I have not found and further damaged or frayed wires lower in the harness. I am wondering if there's possibly a break in the main ground. But that may not explain why the rear is also not working.. unless they share a ground. This is a very frustrating issue.

 

Update 12 Sept

I lifted up the interior carpet on both the driver and passenger side to find some broken spliced wires amongst other wiring issues. I repaired approx 12 wiring issues, including four 12 gauge ground wires. This seems to have not fixed anything. I have removed the fender liner and tried to find any issues with the grounds or wiring harness, no issues found. One point to note is I do not have any turn signal indicator sound, even from the passenger signal which is functioning properly. With the key in the ignition the hazards do not make a sound either, however, with the key out the hazards make noise as per normal.

At this point I am going to order a BCM from a local wreckers with the same year/model package. Hopefully the BCM will fix the issue, I will update in the next week or two once I receive and install the part.

 

Update 18 Sept

The used BCM was installed, the one located just above the gas pedal #7L5 937 049 C, and all signals are working properly once again. I guess ours developed an issue but I'm happy everything is finally working again.