Trailer connector troubleshooting

[Edahall]

2001 GMC Yukon. I am getting no voltage out of this right turn signal trailer connector. The rear right turn signal does work on the vehicle itself. Where do I look next?

[Palf70Step]

I would trce the trailer pigtail back to where it joins the main wiring loom for the rear lights. I think mine was right behind the license plate area on my 2002. Then inspect for damage to loom. I would imagine you might have to unwrap it and check at the solder joint. You can also check on the pigtail socket where the wire enters the socket.

[hatzie]

On the 1999-2014 GM light trucks there's a junction block on the LH frame rail with four Delphi Aptive Metripak GT 280 connections.

1. From the cab,
2. LH tail,
3. RH tail,
4. Trailer.

Get out your back probes and Voltmeter or test light to check for juice at the connector on the J block.
It'll look like this...


The PDF in the link below is the General Motors Light Truck Upfitters guide for the T800 trucks.
Page 79 is the J block plug placement guide.
Pages 91-94 are the J-Block plug pinouts along with connector and terminal part numbers.
https://www.gmupfitter.com/files/med...plications.pdf

It's not impossible that the J-block is bad. Don't bother with the Dorman part get a used one.

[biketopia]

There's a separate fuse inside the interior fuse panel for the trailer turn signals. After verifying that works, then check the in and out of the junction block as they are know to fail or have dirty connections and broken wires.