So, I have a couple electrical gremlins going on. The hack job wiring in this truck pisses me off. I'm working on removing all the shady stuff, but there are several areas that have me stumped. These are two of them.

I'm wondering if I have a couple bad relays.

When I turn the headlights on, everything is fine. But, when I turn them off the parking lights stay on. I have to pull the #4 fuse under the hood to get them to turn off. Then when I put the fuse back in they stay off. This happens every time I turn the headlights on/off.

Is there a relay that runs the parking lights? Could this be a bad switch?

The other two issues are with the windshield wipers:

The first issue is that when I turn them on, they will not return to the down position on their own. I have to manually turn them off in the down position. There is also no delay. They are either on or off. I assume this is related.

The 2nd issue is that when I push the fluid washer button the windshield wipers stay on until I turn the key off. They will not stop until the truck shuts down. This also could be related the issue above.

This truck didn't come with an owner's manual at all. Its a 1994 PSD. I would love a fuse and relay layout and have been searching for one, but can only find them for 96-97s and they are different.

 

Okay, I figured out the wiper issue. Its all related to the wiper interval module being bad. I will grab one of these.

Still working on the headlight issue

 

Scratch that last post. Just swapped two other ones in from the junk yard and still have the same issue with the wipers.

Also garbbed another headlight switch and am having the same issues with it as well.

 

its so hard to diagnose electrical problems this way. but it sounds like the relay is switching its own coil power causing it to latch. so i would say you need to inspect all the wiring from the relay to the lights. paying close attention to anything that doesnt look "factory"

 

The problem is that most of it doesn't look factory. The PO wired in LED rear fender lights. Then the owner prior to him had this brush guard with four fog lights on it wired into place.

What I just found out is that the #4 fuse under the hood turns off the running lights when they are stuck on. But, when that fuse is pulled, the running lights still operate normally when the headlights are on. The problem is that I don't have a 94' wiring schematic or fuse location diagram. I need one for a 1994 PSD. Its different than the 95+ from what I can tell.

 

Found it. #4 is "trailer back up and trailer running lamps" So, I assume that something must be wired wrong in the 5th wheel hitch wiring. I will just pull that fuse for now until I can get some time to diagnose it.

Now I need to figure out this wiper deal.

 

Maybe change out the https://www.ford-trucks.com/forums/1...ml#post9952744

 

Need to bump this.

At this point, I have ironed out everything on my truck except the wiper issue. I have swapped out the multi function switch with no difference.

There must be a relay for the wipers somewhere, but I cannot find it. Anyone had a similar issue with the wipers not returning to the down position on their own or not stopping once the washer button is pushed?

 

Bingo. Gonna do this tomorrow.
https://www.ford-trucks.com/forums/5...-cost-fix.html

 

Well, I would bet that this fix would work for most people. I was able to just pull off the cover, but it seems that one of my contacts is broken off. I'll grab a new motor at the pick n pull tomorrow morning.

 

Good find on that link and good luck.