'02 Mustang V6-Need help with random electrical problems!

I have an '02 Mustang V6 Convertible. 163,000 miles. I recently tuned it up with new plugs, wires, fuel filter, air filter, oil and filter change, (1) downstream o2 sensor (it was broken and the check engine light was on). The o2 sensor put the light out and the car was running great for a couple of days. The first problem was that the brights would not work. After sitting for a couple of hours the brights started working but the radio and the wipers quit working. At that point, I checked all of the fuses and inspected all of the relays and found no obvious problems. I then started the car and the wipers and radio worked perfectly, however the car won't come out of park (without tricking it) and the cruise won't work. So, I checked the brake pedal switch. It looks fine and always has been. The cruise is related to the same issue. My thinking is that it could possibly be a bad ground (although I haven't anything yet) or possibly a Body Control Module. What do y'all think?

Lights, Radio, and wipers!
Do all the radio controls work on the steering wheel?

Maybe you got a bad clock spring.

Lights, Radio, and wipers!
Do all the radio controls work on the steering wheel?

Maybe you got a bad clock spring.


It only has the cruise controls on the wheel....the lights, radio, and wipers are working perfectly now....????

IT could be a module or faulty relay. Let me pull up the wiring diagrams for this vehicle when I get home this evening and I will also post them for you. I'm on my way out the door now or else I would look deeper for you right now.

IT could be a module or faulty relay. Let me pull up the wiring diagrams for this vehicle when I get home this evening and I will also post them for you. I'm on my way out the door now or else I would look deeper for you right now.


Thanks man....I'm looking forward to it.....

Your issues may be a result of more then just one thing. High beams and directionals would be controlled through the multi-function switch on the steering column. Since you have duel filament light bulbs, the only way brights would not work if is MFS was not working properly. You may also notice no wiper action as well.

As for the radio and wipers, it reminds me of a TSB on other fords where the Battery Saver Relay often times goes bad in cold weather or after periods of inactivity, then randomly starts working again after some driving. This would also affect the power windows and power locks as well as interior lights.

Though a lot of what you described, sounds like it could also be related to the GEM module as it controls the ground sides for most of the things you listed as having problems. I know some years had issues with water leaking and shorting the GEM module out, but I wouldn't just scrap the GEM without further testing.

If you were strictly not able to get the car out of park, I would suspect the BOO switch or Brake Shift Interlock.

Your issues may be a result of more then just one thing. High beams and directionals would be controlled through the multi-function switch on the steering column. Since you have duel filament light bulbs, the only way brights would not work if is MFS was not working properly. You may also notice no wiper action as well.

As for the radio and wipers, it reminds me of a TSB on other fords where the Battery Saver Relay often times goes bad in cold weather or after periods of inactivity, then randomly starts working again after some driving. This would also affect the power windows and power locks as well as interior lights.

Though a lot of what you described, sounds like it could also be related to the GEM module as it controls the ground sides for most of the things you listed as having problems. I know some years had issues with water leaking and shorting the GEM module out, but I wouldn't just scrap the GEM without further testing.

If you were strictly not able to get the car out of park, I would suspect the BOO switch or Brake Shift Interlock.


Thanks for the info.....I just found the problem....it was a bad ground. I guess it was playing havoc with the voltage.......John

Thanks for the info.....I just found the problem....it was a bad ground. I guess it was playing havoc with the voltage.......John
Definitely, your models should be doing to the ground side switching. Good find.