My instrument cluster lights don't work on my 93 D350 and the previous owner has the clearance lights and running board lights along with the rear running lights wired on a toggle. I read on here about the headlamp switch issues and took it apart last night. What I found was a lot of wires nicked and missing insulation plus a burnt terminal in the headlamp switch connector which took me to the burnt wire (green) leading into the back of that connector. So I picked up a new pigtail and switch. I also noticed a length of harness wrapped in some foam tape and took it off to reveal a relay of some sort. What is this relay? I also found a separate 2 wire harness that fed into headlamp switch harness (pink wire and black/yellow) that had a connector that is in really bad shape. Can someone shed some light on what that relay and this 2 wire harness is for? Thanks in advance.

 

sounds like a motivated assault to upgrade the rotten loads the switch cant handle with most the bulbs burnt out, you can identify the job the relay is doing, then track the problem originating the (upgrade?) repair, the pink might have a red stripe, that's from fuse #8, supply power, the black yellow, is rear lights, radio, front clearance lights, and front lights as the diagram shows

 

Yep, the pink has a red stripe. I'm guessing with it and the black/yellow being destroyed at the plug that led to the toggle mod. Looks like I have many hours of playing contortionist and laying under the dash ahead of me. Thanks for the info. I really need a FSM.

 

The D350's have 9 more lights on that switch than it was originally designed for. Add a trailer and you have more load.

What I do is take the tail light wire that comes from the switch, drive a relay with it, and run the load with the relay. I supply the relay with a separate fused circuit from the battery. I mount the relay to the lower dashboard plastic with a machine screw and nut. Out of site, but easy to get to for service.

I also built a slave supply box for all my trailer circuits, with fuses and relays for everything. Fifth wheel trailer has slave relays for the second trailer. With the 4 way flashers on, the rig sounds like a pinball machine.

The headlight switch connector is pretty expensive. There are many Chrysler products that use the same connector, and most of them don't have the overloaded tail light circuit in them. 3 minutes with a wire clipper, and usually 5 bucks gets ya one.

 

try faxon in riverside California, great original manuals

 

Thanks again. Im slowly working through this wiring mess and plan on doing the relay upgrades. The wiring is a mess everywhere but I'm trying to get through it. There is a 7 pin connector inside the bed (Im guessing for PO slide in) that has the drivers fenderwell an absolute mess. This is a big undertaking for someone who isn't electron friendly like myself. It literally looks like Edward Scissorhands worked on the wiring. Everything is nicked up and cutup. Just too good of a truck to let go though.

 

Here's the trailer harness/fire starter I removed before I re-wired mine.

 

Haha. I'm going to have the same, I'm sure. One other thing. I had to rebuild the wiper system and replaced the wiper/signal switch and now "off" is intermittent and "high" is off...how does that happen?

 

What happens in the intermittent positions.

Wires are interchanged.

Yep, off is a powered circuit. It puts power to a terminal that goes to a switch in the wiper motor that is off in the parked position. When you turn it off and the wiper is in any other position, it will continue to run till it's parked, then this switch opens.