I have a 2001 manual Mustang. Recently the reverse lights stopp working intermitently. Is there a switch or relay that might be going bad?? And where is it located?
Sounds more like the switch for those lights fried itself. My headlights did the same thing when I fried the headlight switch, and lemme tell ya, rt. 81 in a driving snowstorm at night with intermitten lights = scary as all hell.
Looking at the wiring diagram in the Haynes manual, I'd say you need to replace the "backup lamp switch" or the "transmission range sensor" which, if I'm reading this diagram right, are attatched to the reverse lights, or "backup lights" by black and pink wires. Where the backup light switch is actually located it doesn't say, but the transmission range sensor is located on the transmission (surprise). I'd advise seeing if you can't ask at a local shop if they know where the backup lamp switch is, or call a Ford Dealership. I think it's most likely the switch, because the transmission range sensor would give you other problems as well if it were going bad, and if you manage to find the switch and take it out, it'll be very obvious if it was causing the problem (it will be corroded, cracked and/or burned). Hope that helps. Good luck.
Switch is located on the driver's side of the trans. It is located directly on the side and will have a wire running to it. If you take the harness off, it will look like a big nut with two prongs sticking out of it.
When you shift to reverse, the 5-R lever inside the trans depresses a ball on the switch and signals the lights.
To test the switch take the plug off and shift to R. The switch should have continuity when in R and none when in any other position. If it doesn't replace it. Jumper the two ports ont he harness and the R lights should light up.