Hey guys I'm working on a friends 02 F350 CCLB Lariat LE 7.3L. The parking lights on front are working, the headlights are not, fog lights are not working, when the running lights are on the third brake light is lit up and the rear tail lights and tag lights are very dim. when pushing the brakes the running lights and third brake light go out and brake lights on the rear do not light up.

with the running lights OFF, key on. the third brake light works correctly but the brake lights on the back light up very very dim. with the 4 ways OR turn signals on the running board entry lights blink and so does the third brake light (dimly). .... the little lights on the dually fenders don't work at all.

the only time the headlights will come on is when the key is on i guess those are the DRL's.

need help as the truck cant be driven at all with no brake lights or even running lights.

I have checked all fuses inside, they are all good and all have power except fuse 31,32,33 and fuse 9. which is normal because they're unused according to what i read on internet.

any ideas where to start would be a big help.

 

The first thing I'd be looking at is the earthing points for the lighting, remove, clean & refit with a bit of dielectric grease if you have some.

 

shovelheadrob is correct, you have an open ground in the light circuit.

Don't be surprised if you find that you have multiple faults, the list of those doesn't support the theory of a single point of failure.

 

If you go to the website BBB Industries- Premium Alternators, Starters, Power Steering Products You will need to register for a free account, once you get that set up then go to the link technical information, hover over that and you will see the option for TSB's & Wiring Diagrams. click on that and then put in your vehicle information and then you should be able to go and look up the wiring diagrams and go from there and get what you are looking for if it comes to the point where you need to check the wiring, but I would try what the fellas were saying above first