No power to trailer on / running lights

[RZ Lee]

I have a '23 XLT Hybrid with a factory hitch.

I recently lost power to the running light circuit on the 4 flat trailer plug. I got a dash message that said something like

"Trailer Light Fault Detected".

The turn/brake lights work normally on the plug and trailer.

I've tried multiple trailers and an electrical tester to confirm that there is no power to the brown (on) circuit at the plug.

This may be coincidence or........I bought a cheap Amazon hitch plug brake light. My problems started after I tested it in the hitch and plug.

I will get it to the dealer, however I'm on a month long camping trip and don't really want to stay in one place for a week to try to get this fixed.

I did a work around and wired a set of trailer "on" lights into my flex plug in the bed. So when it starts to get dark I pull over and plug them in so I don't get rear ended.

Has anyone else seen this problem with their 4 flat plug?

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[Hot Runr Guy]

Have you looked at the fuses, in the under-hood box? Fuse #37 is the trailer parking lights.

HRG

 

[RZ Lee]

Have you looked at the fuses, in the under-hood box? Fuse #37 is the trailer parking lights.

HRG

Not yet but good idea - I will this morning. Thanks!

 

[Tom 71 Maverick 24]

Have you looked at the fuses, in the under-hood box? Fuse #37 is the trailer parking lights.

HRG

I just wanted to reply to say thanks - I had the same problem and it was the 20 amp fuse #37.

 

[Tom 71 Maverick 24]

I just wanted to reply to say thanks - I had the same problem and it was the 20 amp fuse #37.

I just hope that my trailer wiring doesn't have an issue. I guess I'd better check into that before my next towing trip.

 

[Hot Runr Guy]

I just hope that my trailer wiring doesn't have an issue. I guess I'd better check into that before my next towing trip.

or bring a LOT of fuses,,,,,,

Hahaha, HRG

 

[Tom 71 Maverick 24]

Trailer wiring checked out.

Interesting thing about LED lights (which my trailer uses) is that your ohm-meter doesn't read the usual amount of resistance that you'd find with ordinary incandescent bulbs. So, all I could really determine on the trailer was that there were no short circuits.

The true test, plugging it in, worked just fine.

 

[dochawk]

use the diode checker setting; there should be continuity in one direction, and not the other, on a working diode (LED or otherwise). I can't imagine it passing that but not emitting light.

Again, the diode setting, not general continuity--the voltage may not be compatible. You may burn out something--the LED, your meter, or ??? if you put random voltages across!

or bring a LOT of fuses,,,,,,

oh, so many fun trips!


On the outskirts of phoenix, my '93 Fleetwood started suddenly overheating. I found myself out in the heat in a Home Depot parking lot building a bypass to the relay for the main fan--mounting a toggle switch with spade prongs and stiff wire, pulling ground from a different socket. Before I left, the second fan (on with AC) started sassing me, so I didn't mess around and did it, too.

(this was after the trip where the overheating was closer to Tucson, and after a couple of days hunting down and replacing the thermostat, the problem was that there was a thermostat in the thermostat housing! Actually having the FSM loaded onto my laptop, I found that GM, in its wisdom, had used the standard thermostat housing off the block, but there wasn't supposed to be a thermostat in it! Instead of that standard thermostat, theres a thermostatic assembly under the engine. )


A couple of trips later, I got pulled over in Tucson--no tail lights!

Huh?

the officer was helpful--it's usually a sign of a drunk driver. But seeing my headlights were on, he helped check what did and didn't come on. After discussion, I rhythmically touched the brakes for the right home to stay lit up.


Bad connection *to* the fuse box. So got a fuse extender to tap +12 from the next fuse over and added another toggle switch.


The last trip to Tucson, the transmission gave, and I had to rent a haul to tow it back.

It's one of the cars I'm about to give up. Nice car, but with two other old Cadillacs, it's the one that's going to go. (those came with a chevy truck engine, anyway! They don't really drive like a cadillac, just a smaller big GM)

I learned a lot about roadside repairs on that car . . . and these were the only repairs it ever took!.

Lessons:
1) keep it out of Arizona! (but my MiL loved it, and was disappointed when we came in the van)
2) in a pinch, a standard spade connector fits automotive fuse sockets.
3) always have a meter in your car on road tips.

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