Electrical problem?????

[Dambnicetruck]

I can't get the running lights on my trailer and camper to work? All lights on the truck are working fine, and the signals and brakes work great, but no running lights? I checked the fuse, it was burnt, but I replaced it, and still no lights. Fuse is still ok. Under the hood there is a power distribution box. Unfortunately there are no diagrams of where all the fuses and relays go, so its trial and error. There was one 30A large fuse(BIG) and it was burnt. I figure it may be the problem so I jumpered it for now, but still no lights. Don't know what the fuse ran, cause nothing changed with the jumper on? Any one have a diagram what those fuses are for, theres at least 10 big fuses and 10 regular(Roughly). I sure need that, and ford wants big bucks for a diagram(CROOKS). Any way, got the multimeter out and I traced all the way to where the plugs(2) splice into the regular line. Funny enough, there is no power() Try'd to go further but it goes to a large plug on the fire wall, and all the colours change about every foot(DAMB FORD,WHY NOT STAY ONE COLOR PER CIRCUT, DUMBIES) any way, can't figure it out. At least the truck lights work. I think I might have to abandon the trailer circut and just jumper from the truck lights, do you guys think the fuse can handle the load of truck, trailer, and camper? HELP!

 

[towcat]

This is why so many of our trucks burn to the ground. firstly, you need to post all the pertinent info on your truck down on your sig line, so the rest of the board knows what you got and how to answer and help. without knowing what year truck you have, all I can do in the meantime is give you a little info on why this is happening. firstly, Ford in all their brilliance, put the entire lighting amp load through the headlight switch. This is barely adequete when you are running just the lights on the truck and the wiring on the truck is presumed healthy. Where you start running into trouble is if the wiring has built up some internal resistance due to issues like roadsalt starting to corrrode the wiring, or wiring heating up when too many accessory lights are added. What to do....first, the critical point of the lighting system must be opened up and inspected. this means opening up your dash pannel and inspecting your headlight switch. The wiring block that snaps into your headlight switch must be inspected for heat damage, either melting, distortion or charring. Secondly the headlight switch must be inspected. Depending on the year of your truck, the connector that controls the accy lights is on the bottom row or second row up. Look for visiual damage like the above items for the connector and do the sniff test. Smell it to detect any internal fire damage or overheat damage. Just for safe measure, I'd reccomend changing the switch. The part is roughly $35-45USD, so its mainly peace of mind. In the engine compartment side of the truck, I would be putting in the relay for running the accy lights. Once again, the year of your truck is critical to find out which color wire to cut and splice in the relay. Once done, the relay takes over the lighting load and the headlight switch has to only work the relay, therefore taking the load off the switch and prevents an electrical fire from occurring. Good luck!

 

[Dambnicetruck]

Sorry, I have a 94 factory turbo f250 2wd with the E4OD Trans. It has the tow package. I have done some tracing, and it appears that tow package means it has signal wires, then it also has secondary signal wires that go to the trailer plug. They only seem to work if the engine is on, and the other two work all the time with key on, and engine off or on. So I still can't figure out which fuses in the power distribution box under the hood are for the lights. I have a diagram on the panel inside the cab, but the 4" by 10" box under the hood has no diagram!!!! There is also two relays right next to it, which I believe run the tow package. But know diagram for that either!! The head light switch is fine, and the plug to it looks like new, no burnt smell. I tapped the running light wire at the back bumper for a new power to the lights, and it works great, and since the only extra wires in the tow package seem to be signal, I figure this is what they did anyway, just somewhere else. Funny thing, I lost the left signal after the repair, and thats how I discovered the extra signal wires. The guy that originally put the camper plug in, had tapped the wrong wire for the left signal, and the right wire for the right signal. I was testing with the engine off, so I lost the left signal, because it was hooked to the wrong wire. Once the engine was on, it worked.. Not only that, I blue a fuse in the power distribution box(10a), and it was for the left side only????I havn't found the right fuse yet, because of no diagram, but I assume its the other 10a.HEHE, what a mess ford makes of wiring. Did I mention the wire changes colors three times on its way to the back of the truck. Why do they do that! Any way hope the jumper holds up. If not , jump it again.

 

[rray32539]

The trailer lights are working properly if they are NOT operating when the engine is off. Your batteries will go down really quick if the trailer lights weren't isolated from the truck. That was the method to the madness there. As you were trying to test your lights with the engine off, that was part of the problem. The only circuit that will work with the engine off are the hazard flashers.

You are probably right about the other 10 amp fuse. As I recall, each side has its own fuse, as does each headlight.

Also, check www.autozone.com . They have a lot of the Ford wiring diagrams online, you can look at them free of charge.

 

[Dambnicetruck]

Thanks for the help guys. All better now, except now my tranny starts off with the O/D off, and I have to manually turn it on. I used to never have to touch that button unless I wanted it off. How can this happen when I never touched that fuse, or harness?

 

[Dambnicetruck]

ok. Trucks retarded. I can't believe it. Now its back to normal, and starts in O/D. Is it possible the computer is screwed up, and is causing this? By the way, what does the computer run in these things?