Anyone know where there could be a fuse or fusible link for the rear trailer plug. I have a '98 E350 and towed my car down to a track last weekend, everything (lights on trailer, brakes, directionals) worked great on the way down, but when I went to hook up on sun. to come home, nothing worked on the trailer. I have since hooked up my trailer to a friends truck, and everything worked on the trailer. any ideas?

 

Speaking for my '99, the trailer systems are all separate from the rest of the vehicle. This means that there are fuses & relays for each system. Trailer lights, trailer brakes, charge line, the whole 9 yards.

According to my owner's manual, here are the locations for each:
Under dash
Location 15 - 5 amp trailer battery charge relay

Power Distribution Box under hood
Location 5 - 10 amp Right trailer turn signal
Location 6 - 10 amp Left trailer turn signal
Location 14 - 30 amp Trailer running/back up light relay
Location 20 - 20 amp electric brake controller
Location 22 - 40 amp Trailer battery charge relay (modified vehicles only - may be blank)
Location C - trailer back-up lamp relay
Location D - trailer running lamps relay
Location E - trailer running lamp relay

If memory serves right one of D or E is actually the charge relay itself.

I would start by checking your plug on the vehicle before knocking myself out looking at fuses. If all the fuses are blown, the most likely place for it to happen is where the trailer plugs into the harness. I'd be willing to bet that the fuses are fine and the vehicle plug is bad.

 

Hey thanks, Dave, it seems we have almost the same van. mine is a '98 E350 vw/ 6.8 v10. its a Club Wagon w/ the Chateau option. I did probe the plug under the bumper briefly and had nothing at all 7 pins. I also went through the fuse panel under the dash and the hood, not a single blown fuse. have you seen an entire plug fail @ all the pins? thanks for the help.

 

Before I say any more, I have to ask a question. Did you tick off anyone at the track? Ever since I read your original post I've been trying to ignore the idea that someone got mad at you and slid under your van and clipped your harness. The racers around here almost always leave people in the pits to avoid stupid passive-aggressive stunts like this. I think you will find your problem once that spare is out of the way, you will see what the trouble is. Honestly, I have never lost everything all at once like that. I've had intermittent problems, but not cold turkey unless there's been damage to the harness itself.

Can the plug fail? Possibly - it depends on whether or not the plug is a factory installed unit or one that was installed with aftermarket parts (like mine). It is rare for the factory harness to have problems because they tend to stay sealed up pretty good. Aftermarket ones can let moisture in which can corrode the connections and cause problems rather quickly.

Once the spare is out of the way, trace the wiring harness from the bumper to the driver's side frame rail just behind the rear axle. If you have the factory 7 pin harness, there should be two connectors where it hits the main harness going to the front. If its a home-made harness, there will be butt connectors or something similar tying it all together. You could disconnect things here and test to see if you have power etc at this point. Remember, you will need to have the ignition on to test these as all of them are on relays. If there's power here, then the problem is in the connector.

 

I really don't think anyone would have done that, and I have crawled under the rear of the van and followed the harness to the first connection and it was still connected. it was just foward of the spare.

btw, it has a factory installed harness. I was too lazy to follow it to the front of the van though. maybe I will do that tomm. also wanna take the plug apart to see whats up in there.

this is really annoying me. it shouldn't be this difficult to find such a problem but for some reason its just not an obvious problem.

 

I didn't think that you would have missed a cut harness - I just had to put it out there.

I'm betting there's a problem in the connector - might be time to replace it. They can just wear out over time.