Wiring harness connector identification

[jmgallag]

Hi,

I have a 2004 Armada with a factory tow package. My problem is that the right turn signal pin on the trailer socket is dead. The pin should be energized by the Body Control Module, and the manual shows two harness connectors in between. Checking the BCM shows that it is energizing the correct pin at the appropriate times, so the cause of my problem must be in the harness.

My question is, are there identifying marks on the harness connectors? I have not been able to find any that match up with the manual. Also, the wire colors in the manual match at the trailer socket, but they do not match at the BCM end. It is very difficult to discern the wire markings at the BCM. Is there a secret to identifying the intermediate harness connectors? I took the panel out of the front passenger footwell and uncovered several connectors, one of which I think is first connector, but I can't tell.

The connectors in question are M31/E152 and E41/C1.

Thanks