240DL speedometer cuts out

[BP125V]

Recently my 1990 240DL speedometer has been cutting out intermittantly. When this happens, it also seems as though the car does not roll as freely, it is almost as though the brakes are on very slightly. Any advice as to how to fix the speedometer? Can I do this myself? Also, any ideas as to why the car would run differently when it cuts out?

thanks,
Bill

[LaRy]

I have been studying the electrical drawings for your car and hopefully this information can help you a little. The speedometer is getting 10 volt power supply from a voltage stabilizator unit also used by the rpm-meter and fuel gauge meter (so if they works, the stabilizator unit works). The speed reference is coming from a sensor in the rear shaft gearbox. It is a sensor getting speed frequency from a teeth wheel. Check those cables, I can just imagine how they looks down under there after 15 years of dust, grease, salt and water.

Maybe the electrical solution for the speedometer is the same as for the 740 series. The 740 has a wellknown problem that the speedometer is dead sometimes. Try to give a hard hit at the upper side of the dashboard. If it helps for a short period, it is a small electronical IC circuit that is broken in the speedometer.

The speed sensor in the rear shaft gear is assembled probably less than 1 mm from the teeth wheel. If you have a bad bearings this distance will vary and it will be male function. Do you hear some noice from the gear? I just think of this because you say that the car is giving some sort of feeling that it is running heavy at the same time as the speedometer is dead.