1996 E300D Speedometer/Odometer Broken

[briandownunda]

I have a 1996 E300D that has an electronic speedometer and odometer that do not work. I have been using the tachometer to estimate my speed, however, my 15 year old daughter now has her driving permit so I figure I'd better fix it soon. Any help in diagnosing this would be most appreciated.

Here are the symptoms:

1) Functionality is intermittant, although recently, they almost never work.
2) In cold weather they seem to work more often.
3) The ABS and ETS (Electronic Traction System ?) lights are on, when not functioning, which is almost always now.
4) Sometimes they will start working after honking the horn, also, sometimes they start working after going over a bump in the road.

I was told by a mercedes mechanic that the engine wiring harness was bad & needed replacement. I replaced that but it made no difference (was just hoping it had something to do with that). In all fairness to the mechanic, his reason for replacing the harness had nothing to do with my speed/odo failure.

Any ideas on how to troubleshoot this problem ? I have a mercedes manual so could probably dig up a wiring diagram for this circuit.

Thanks in advance,

Brian