Tow Tail lights not working - I'm stumped, need help

[kcjaz]

I've been fighting an electrical issue where my tail lights do not work at the trailer plug. Its a long story but the short of it is that I tied into the OEM Tow harness to wire up the aftermarket tail lights on my Dissent rear bumper. It all seemed to work when I did it. My bumper lights went out at LCDC in July but that turned out to be a connector that wiggled loose. Then they went out again and it was one of my splice connections that shook loose (poor install quality - me). I fixed that and everything works except the Tow Tail lights. The Tow Tail light circuit is dead up to the supply 30 A fuse (which id good) in the fuse box under the hood. I have a thread on this in the 200 forum. You can go to post #23 to see what I have done to trouble shoot. There doesn't seem to be any voltage getting to the rely (which I tested and is good). I'm stuck. I'd appreciate any advice you gurus can provide.

Dissent rear bumper lights issue

I’ve got a loose connection somewhere and I have no running or tail lights at the trailer plug. It all worked when I initially installed the lights so something has just come loose. What I don’t remember is if the left and right tail lights on the bumper ever worked. I have brake lights and...

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[1MAC]

I love chasing electrical problems. Come to my house and we can both scratch our heads. Did you ever get the fuses pulled to check them? Some fuses have little pin holes that you can probe without pulling the fuse.

 

[kcjaz]

I love chasing electrical problems. Come to my house and we can both scratch our heads. Did you ever get the fuses pulled to check them? Some fuses have little pin holes that you can probe without pulling the fuse.

Thanks. The 200 (and me) are down at Pomme de Terre (our lake house). I did check continuity through the fuses. All good. I just now checked for voltage with the 30A fuse pulled at read 13v on the hot side so the fuse socket is connected to the battery like it should be. I also got 13v on the relat trigger pin that connects to the fuse in the fuse box but I don't have any volts on either pin/slot in the relay socket. I'm thinking that must be the problem. No idea how that could have got messed up. Doesn't seem likely either.

 

[kcjaz]

I don't want to pull the fuse box to check the connection between the fuse and the relay. What if I put an "add-a-fuse" thingy in the 30S fuse slot and jumper to the relay load pin? Not sure if I'd have to jumper the trigger side too as that goes into the ECU circuit somewhere.

 

[kcjaz]

Fix it. Root cause is that I'm stupid. 30A Towing fuse is not the same as the 30 A Tow Tail fuse. What's nuts is that since July I've had 3 failures in this one circuit. 1. Loose connector. 2. Broken splice connection 3. Missing (yes missing) Tow Tail fuse. I have no idea how the Tow Tail fuse went missing. I can only assume that my Dissent tail lights never worked. I had brake and blinkers just know tail lights. I only noticed the no tail lights when I hooked up a trailer at night in October. The first thing I did was check the fuses but I wasn't actually looking at the right fuse.

On the upside, I am much more familiar with my wiring diagrams now. I ended up creating a complete searchable PDF of all them from the FSM files I had. Very useful if you can read them, which seems to be my challenge...