The car is a 1981 300D. Two questions:

What could be causing the glow plug light on the dash to stop coming on like it normally did? Yesterday, it began turning off much sooner than it ever has. Also, with the engine warm and upon restart, the light barely comes on and then goes off. The light does not come on again after starting. The car seems to start OK; however, it may have taken a bit longer this morning to start, but the outside temp was a 10 or 20 degrees F lower, which might explain that.

2nd question: My backup lights do not work and there is no voltage to the bulb socket on either side. The fuse is good. I assume the switch is the best place to start. Where is the switch for the backup lights?

The switch is on the side of the tranny.

The glow plug will react differently dependent on temperature, however, if one of the plugs goes out, it could flash at times.

__________________
Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS