My worktruck is a '02 F550 4x4 XL. A few nights ago another guy took it out to work storm outages and in the process of the night, the gauge cluster lights and all outside marker lights quit working. The cluster reads and seems to work fine, yes the scroll switch is all the way up, and the headlights work fine on high and low beam, the high beam indicator even lights up on the cluster. I've checked all the fuses that I could even associate all of this to and all seem ok, any suggestions? thanks

 

There is a breaker somewhere in the system. I "blew" that circuit on mine as well. Some combination of turning lights and ignition on, and a click came from the headlight switch area and it all started working again. I'd say start by checking for power in the switch and then output from the switch.

 

Here's what I found from my wiring diagram. Mind you it is a 2005, so there may be some differences, but often they are the same.

Fuse 17 feeds the light switch so check that first. There are 2 plugs going into the main light switch - one has 6 pins, the other has 12. In the 6-pin connector there is a wire that is LB/RD (light blue w/red stripe). That wire feeds the IC lighting. It also shows an unidentified "microprocessor" that feeds this wire. If somehow that thing got blown, then you would probably lose the IC lights.

So pull the switch out so you can access it (leave it connected) and check voltage on that LB/RD wire to ground (the black wire is GND) with the lights on - should be 12v. Next, there is a Brown wire on the same plug. Check voltage on that to GND also - should be 12v also. The Brown wire feeds the mystery "microprocessor". If you have 12v on the Brown wire and none on the LB/RD, then the microprocessor is probably the cause. I suspect that is inside the light switch, based on the skematics, and you would probably have to replace the switch unit.

If this doesn't point you in the right place, let us know.

Edit: looking it over more, the headlight switch migh tbe bad. There is another Brown wire on the 12-pin connector on the light switch. This one feeds the Brown wire on the 6-pin via a splice. If you don't see 12v on this one either, then I'd bet that the switch is bad, but you'd need to check a few more things first.

HTH
-Dave

 

Really appreciate the help, after I posted that I went out to look at it some more. I guess I should mention the guy driving the truck when this happened was a degree having, 10 year mechanic for that other big vehicle co. (GM). His solution to the prob was to beat the s'@t out of the dash (namely the area around the light switch). The switch is sunk in about 1/8" from normal and I asked him if that was how gm fixed their stuff. His reasoning was "It's a Ford, who cares?" I told him to take the pickup and his belt and hooks next time, just stay outta my truck. Sorry for the long post, but thanks again.
chris

 

I bet u wanna knock his lights out

 

I had the same thing happen in one of my older trucks and all it was was the light switch. It was an '89 but it did all the same stuff that you mention. I know you said that the head lights work but check the tail lights also. If they dont come on with the switch on change it out and it will all be fine. I HOPE! Good luck!! Oh, and that is how chevy guys fix things and send him the bill for all that needed to be fixed. Tell him he broke it with all his dawm banging!! That is not a guy I would want working for me if he would treat my vehicles like that!