No Power to Trailer Turn Signals and Brake lights

[Hikerdogs]

We recently purchased a 2013 Winnebago Adventurer. When I was setting it up to tow our Jeep I found there was no power for the left turn/brake light, and the right turn/brake light at the 7 pin trailer socket. All other pins in the socket are working correctly.

All the brake and turn signal lights on the motorhome work, and using the Winnebago online wiring guide it appears all the wires from the socket are correctly attached to the Ford wiring harness.

All the fuses and relays are present and good.

Before I start looking into the wiring harnesses has anyone run into this problem before? Hopefully someone has some insight. I hate to reinvent the wheel if there's information about this condition available.

[FIRE UP]

Hikerdogs,
Well, not sure if Ford and or whoever makes that chassis you're on, makes a total separate set of fuses for your trailer plug like our Freightliner does. It took me a while to find the fuse block that is specifically for the trailer plug but, I eventually did. Now, if Ford has one, I can't even begin to advise you where you might find it.

But, I'm sure that Winne or the chassis maker should have what's needed in wiring diagrams for your rig. Your rig lights will be totally independent of your trailer light fuse assemblies. So, good luck and please post what you find out is the issue so that others may learn.
Scott

[grtharris]

In the Passenger Compartment Fuse Panel The fuse panel is located below and to the left of the steering wheel by the brake pedal. Remove the panel cover to access the fuses. Make sure the R22 fuse is good (same fuse for left and right) and Relay 1 and Relay 2 are there.

[Hikerdogs]

Originally Posted by grtharris

In the Passenger Compartment Fuse Panel The fuse panel is located below and to the left of the steering wheel by the brake pedal. Remove the panel cover to access the fuses. Make sure the R22 fuse is good (same fuse for left and right) and Relay 1 and Relay 2 are there.

Thanks, these were the first things I checked. The fuse is good and both relays are present. I have power at pin 3 on both relays. According to the Ford service manual I should be looking for an open ground wire in circuit 57 BK.

I was hoping someone had found a poor connection, a broken wire or another unmentioned fuse somewhere in the circuit. The wiring harness that contains the ground curcuit probably has a hundred wires in it. It winds up over the steering column before it exits through the firewall. Right above the steering column is a connection. To get to it I have to disassemble part of the dash and lower the column. I was hoping to avoid disassembling everything.

[grtharris]

Hikerdogs, Yes looks like there are 2 connectors and 4 splices before the wire gets to the ground (G-108). Do you have access to the Ford drawings it would nice to look at that ground stud?

[Hikerdogs]

Originally Posted by grtharris

Hikerdogs, Yes looks like there are 2 connectors and 4 splices before the wire gets to the ground (G-108). Do you have access to the Ford drawings it would nice to look at that ground stud?

yes I have access to the Ford drawings. I learned a long time ago to buy the service manuals when you buy the vehicle. In days of old some of the manuals took up 3 feet of shelf space and cost an arm and a leg. Fortunately they're now on DVD so I can print the pages I need and take them to the job.

Now for the good/bad news. The good news is that everything now functions properly. To make sure it actually was a ground problem I isolated the ground terminal on one of the trailer turn relays and put a jumper to a known good ground. I went back to the trailer hitch socket and everything worked as it's supposed to. I then started following the ground circuit back from the chassis terminal to the firewall. everything was intact, but still no lights when my jumper was removed.

I went inside the cab and started tracing the wires to the next connector. It was buried in a mass of other harnesses above the steering column so I decided to go to the relay panel itself and start tracing from that end. I couldn't get my hands behind the fuse/relay block so I removed it from the mount. I placed a probe from my multimeter to a ground wire at the back of the panel and the other lead to a known good ground. Low and behold it showed continuity. I turned on the ignition, flipped the directional light lever and went back to the trailer socket. Much to my surprise it worked. I then tried the other directional, the flashers, and the brakes. All are functioning properly.

I don't know what happened. Whether I had a poor connection at the relays, a poor splice in the harness, or a partially severed wire. Now that everything works it's going to be almost impossible to know what was wrong unless it fails again.

[grtharris]

Yes, don't you just hate it when something starts working and you don't know what fixed it. Hope it holds. But always remember sometimes it is better to be lucky than good.