If it was mine, I'd take the old switch apart and see what's inside before forking out for a new one. If there is any kind of timer circuitry it could be as simple as a bad capacitor or a fractured solder joint. If you dismantle yours, take some pictures and post them for reference.

FWIW, I'd be interested to see if the timebase could be adjusted since mine kicks to low a bit too soon when it's really cold outside.

Quote Originally Posted by jebjk1
I looked over the wiring diagram in my Bentley manual, and I didn't see a timer or a relay. All that I could see that could go bad is the switch or the fuse. Being the fuse is good, maybe it is time for a new switch?