Gary Lewis Posted May 31, 2021 Share Posted May 31, 2021 I was noticing in the relay chart there were different options for fog lights and I did remove some really old fog lights that were mounted under the front bumper. I assumed they were aftermarket but who knows.. Thanks for your help, Gary. In my research Ive seen so many threads of people asking you "whats this relay." Im sure it gets old, but it really is incredibly helpful. Yes, that relay was probably for those fog lights. And yes, there are lots of questions about the electrical systems, including relays. These trucks have lots of options for each year as well as changes from year to year. And, over the almost four decades people have done lots of things to them. So they are sometimes difficult to figure out. Link to comment Share on other sites More sharing options...
swampedout Posted June 6, 2021 Author Share Posted June 6, 2021 Yes, that relay was probably for those fog lights. And yes, there are lots of questions about the electrical systems, including relays. These trucks have lots of options for each year as well as changes from year to year. And, over the almost four decades people have done lots of things to them. So they are sometimes difficult to figure out. I traced the trailer wires back to a connector under the brake booster. Theres a lot of carnage, burnt insulation, exposed wire. Im probably going to replace the connector, relay and all the wiring in between. Link to comment Share on other sites More sharing options...
grumpin Posted June 7, 2021 Share Posted June 7, 2021 I traced the trailer wires back to a connector under the brake booster. Theres a lot of carnage, burnt insulation, exposed wire. Im probably going to replace the connector, relay and all the wiring in between. Good find! I’ve found problems in the trailer wiring on at least two trucks I’ve owned. Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 7, 2021 Share Posted June 7, 2021 Good find! I’ve found problems in the trailer wiring on at least two trucks I’ve owned. Glad you found it. Yes, trailer wiring is frequently an issue. Link to comment Share on other sites More sharing options...
kramttocs Posted June 7, 2021 Share Posted June 7, 2021 Glad you found it. Yes, trailer wiring is frequently an issue. Nice sleuthing! Will echo Dane and Gary. Trailer wiring often falls victim to "do whatever it takes to get it on the road now" when working on the side of the road or last minute trip preparations. Link to comment Share on other sites More sharing options...
FuzzFace2 Posted June 7, 2021 Share Posted June 7, 2021 Nice sleuthing! Will echo Dane and Gary. Trailer wiring often falls victim to "do whatever it takes to get it on the road now" when working on the side of the road or last minute trip preparations. That is why I used a Tee that fits between the rail harness and tail light harness that then runs to the 7 pin trailer plug. I know they dont have the relay but I dont see why I could not add one if I feel I need to? IIRC it is just for the running lights and nothing else. I would pull the rear running light wire out of the plug under the booster and add the relay there using the trucks rail harness to still feed the rear & trailer with the Tee. Then again with a head light relay kit installed removing some of theload off the head light switch would you need to run a relay for the rear lights? Dave ---- Link to comment Share on other sites More sharing options...
swampedout Posted June 7, 2021 Author Share Posted June 7, 2021 Nice sleuthing! Will echo Dane and Gary. Trailer wiring often falls victim to "do whatever it takes to get it on the road now" when working on the side of the road or last minute trip preparations. That is why I used a Tee that fits between the rail harness and tail light harness that then runs to the 7 pin trailer plug. I know they dont have the relay but I dont see why I could not add one if I feel I need to? IIRC it is just for the running lights and nothing else. I would pull the rear running light wire out of the plug under the booster and add the relay there using the trucks rail harness to still feed the rear & trailer with the Tee. Then again with a head light relay kit installed removing some of theload off the head light switch would you need to run a relay for the rear lights? Dave ---- I like this idea about the Tee, but Im not completely sure where/how you suggest splicing it in. I was intending on replacing the relay. Theyre cheap and not too hard to wire in. Things can obviously still go wrong but I see no reason not to have it, especially since Im redoing the wires anyways. Small steps... Link to comment Share on other sites More sharing options...
kramttocs Posted June 7, 2021 Share Posted June 7, 2021 I like this idea about the Tee, but Im not completely sure where/how you suggest splicing it in. I was intending on replacing the relay. Theyre cheap and not too hard to wire in. Things can obviously still go wrong but I see no reason not to have it, especially since Im redoing the wires anyways. Small steps... On the rear cross member, drivers side there is a (likely dirt fused together) plug that connects the rear light harness to the harness that runs along the frame to the front. This goes between those two plug halves. Depending upon what you will be towing (electrical wise) determines the option I'd choose. Link to comment Share on other sites More sharing options...
FuzzFace2 Posted June 8, 2021 Share Posted June 8, 2021 http://forum.garysgaragemahal.com/file/n98611/IMG_20210607_180536.jpg On the rear cross member, drivers side there is a (likely dirt fused together) plug that connects the rear light harness to the harness that runs along the frame to the front. This goes between those two plug halves. Depending upon what you will be towing (electrical wise) determines the option I'd choose. Yep but my Tee has wires coming out that I wired into the trailer connection. That only dose the lights not the trailer brake wire or a battery charge wire so I had to run them down the frame rail to the connection. I just followed the rail harness down the frame. It was when I ran the wires that I shorted out the dual tank switch valve wire and wondered why the fuel gauge was not moving on the front tank? It was using gas from the rear but reading the level on the front Dave ---- Link to comment Share on other sites More sharing options...
swampedout Posted August 8, 2021 Author Share Posted August 8, 2021 http://forum.garysgaragemahal.com/file/n98611/IMG_20210607_180536.jpg On the rear cross member, drivers side there is a (likely dirt fused together) plug that connects the rear light harness to the harness that runs along the frame to the front. This goes between those two plug halves. Depending upon what you will be towing (electrical wise) determines the option I'd choose. Yep but my Tee has wires coming out that I wired into the trailer connection. That only dose the lights not the trailer brake wire or a battery charge wire so I had to run them down the frame rail to the connection. I just followed the rail harness down the frame. It was when I ran the wires that I shorted out the dual tank switch valve wire and wondered why the fuel gauge was not moving on the front tank? It was using gas from the rear but reading the level on the front Dave ---- Uh oh. I will try not to short my fuel wires, I have enough problems already. The good news is I had to leave the truck for almost a full month and got back to it yesterday and it cranked up and held idle for a good while. Ive got one more job for the truck and then I can finally give it some attention. First thing on the list is fixing the rear brakes. Link to comment Share on other sites More sharing options...
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