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Hey Ya'll. I have a 2003 Chevy Express 3500, RoadTrek Class B camper conversion. So, I have an issue where the right rear tail light wiring has a short circuit. When I turn on the lights, the #20 fuse under the seat blows. 1) Does anyone know where the rear light wiring is run from the front fuse box to the rear of the van? Under the van, or inside? 2) Trying to find the short-- I have unhooked the rear tail light assembly socket, so it isn't the tail/brake light wiring harness or the bulb. I swapped the light switch relays to rule those out. It only affects the right rear tail light. The brake light and turn signal works. It does not affect the brake light. Does anyone have experience with this type of short circuit? Unhooked rear brake light harness, so short is somewhere between upper connector and fuse Underseat fuse box. #20 keeps blowing.
Last edited by MrPerkins; Feb 28, 2021 at 12:48 PM.
Reason: more info
Unless we did the actual conversion, we have no definite idea which path they chose to run the wiring. Sometimes it is through the top corner the body then down to the tail lights.
Conversion vans, if you ever took one apart and dug into it, are cheaply made. Entirely possible they ran a screw into a wire somewhere or it's been rubbing on one and finally wore through.
If your van has more or less a stock steel body shell then I believe the wires run along the left roof channel and across and over to the right tail light. But who knows what they did when they converted it.
Does it have a trailer plug? If so, those are common failure points even if installed using GM factory harnesses.
The typical routing for everything behind the cab is down the driver frame rail with the brake lines. If it has a rear light junction block, that’s where the right rear harness will run from and you can isolate if the short is in the harness on the frame rail or in the right rear harness by unplugging it at the junction block. Also note the junction blocks are known for problems, so try bypassing it and if the fuse doesn’t blow the junction block needs replacement.
This is why I asked if it uses the stock steel body. I just swapped a tank under one of these and there's no wiring down the frame rail with the brake line.
The post with the speedometer issue there's a TSB for a rub of the brake pedal arm on part of the harness. Might check there too, although I would guess a short there would affect both lights.
Last edited by William Kisselstein; Mar 1, 2021 at 4:00 PM.
This is why I asked if it uses the stock steel body. I just swapped a tank under one of these and there's no wiring down the frame rail with the brake line.
The post with the speedometer issue there's a TSB for a rub of the brake pedal arm on part of the harness. Might check there too, although I would guess a short there would affect both lights.
The cab and standard frame assembly would be identical to other 3500 vans and trucks (including wire harness routing) but GM would only build these vehicles up to the point where it was ready for a box, then leave the frame exposed for whatever utility was going to be added.
Many companies that install conversions usually design their connectors and wiring to fit that of the base vehicle manufacturer as it’s cheaper and easier than trying to splice wires.
But as others have pointed out, it’s tough to say where the conversion company would’ve routed it. I’d guess they’d start a re-route just behind the cab, as it would be about the only place to safely route the harness to the center or other side of the frame without exposing it to too much heat from the exhaust.
I haven't been under an 03-up with the tank intact but there's no room on the 97-02, there's barely room for the brake line.
A cutaway van camper would not have a stock steel body. But some small conversions are still built with a stock body shell. New York even had these mini-bus conversions to haul prisoners that use the stock body shell from the beltline down including both front doors, but from the belt up have a school bus style body, including a fiberglass filler panel where the middle side doors were.
It turns out that one of the brown power supply wires was shorted between the fuse block under the seat and the right rear parking light. So my mechanic just ran a new power wire. Hopefully that will do it. It is a stock Express 3500 van that has just been built into a camper with a conversion top. Thanks to everyone who provided input.
It turns out that one of the brown power supply wires was shorted between the fuse block under the seat and the right rear parking light. So my mechanic just ran a new power wire. Hopefully that will do it. It is a stock Express 3500 van that has just been built into a camper with a conversion top. Thanks to everyone who provided input.
Glad you got it figured out - thanks for letting us know.
Short to rear parking light
