quote:Originally posted by Bosswrench:
Something not shown on the schematics is the fact that the headlight motor actually draws its power from a jumper wire off the headlight switch; it does not go back to the fuse box. There's two possible male spade lugs available on the side of the switch. Having the jumper on the wrong one will allow the lights to come on but not rise since the lights are one circuit and the motor is another. The lowering function after manually raising the buckets seems to be yet a third power line, probably associated with the limit switches. I ran into this on a '72 and a '73 L model (different colored wires on each, by the way).
Thanks Jack, I'm not sure what caused the failure. I think it was either the headlight switch itself (most likely) or a perhaps a fouled limit switch which caused the lift circuit to remain open even when the headlight switch position called for it to be energized. I suppose it could be a different limit swicth failure that resulted in high current and helped the switch fail. The switch failure looked to be mechanical, not electrical.
Near as I can tell the headlight motor is powered to actuate the headlight doors down anytime the ignition switch is on and when the headlight switch is off (or removed) and it's only the down limit switch that opens the circuit in this condition. So if the the headlight switch completely fails (in a manner like it has been removed), you get neither an up signal nor lights. Make sense? We'll see. It is now wired in the pre-TSB 14 configuration and if I jump the the pink to red/white wires on the switch, the headlight relay changes state and the headlights come on and happily pop up.
Kelly