TDC sensor

[Mr.Nice.]

I've been looking at the wireing diagrams for my 1990 D 405. I'm trying to find out why the rev counter does not work, I recently found it to be electrical.

There appear to be 2 wires (according to the diagram) that go from the instrument cluster to something called a TDC sensor (top dead center?)

The 2 wired connect to points on the instrument cluster labelled "tachometer".

Q1, is one for the road speed and one for engine rpm?

Q2, where, physically, will I find this TDC sensor?

Q3, am I on the right track with this?

 

[Matt]

A stab in the dark, but if it does really mean Top Dead Center sensor, then it surely would be on the flywheel housing?

Cheers,
Matt

 

[John Bridge]

It is best accessed from underneath, it screws into the flywheel housing with one small bolt, this bolt needs to be loosened its a sort of plastic clamp that needs to be prised open with a screwdriver and the sensor can then be pulled out of the clamp, the sensor is looking at the engine side of the flywheel. There should be a cable attached to the sensor it has three wires in it one of which is an earth connection, this cable should go to a brown socket near the thermostat, a brown plug goes from this socket to the tach. I think this brown socket is there so that some diagnostic device can be plugged in and used for determining TDC for setting the pump timing.
John

 

[Mr.Nice.]

Twas Tue, 8 Jul 2003 15:57:36 +0100 when "John Bridge"

It is best accessed from underneath, it screws into the flywheel housing with one small bolt, this bolt needs to be loosened its a sort of plastic clamp that needs to be prised open with a screwdriver and the sensor can then be pulled out of the clamp, the sensor is looking at the engine side of the flywheel. There should be a cable attached to the sensor it has three wires in it one of which is an earth connection, this cable should go to a brown socket near the thermostat, a brown plug goes from this socket to the tach. I think this brown socket is there so that some diagnostic device can be plugged in and used for determining TDC for setting the pump timing.
John

Thanks for that, I'll go poke around. ;o)