W140 Cluster Engine Temp Guage "Dead" WHICH SENSOR CONTROLS IT???

[slimak9]

1992 400SE

The Engine Temperature Guage on my W140 instrument cluster stoped working.

I found 3 sensor mounted on top of the intake.

a single prong sensor.
a four prong which is the ECT sensor.
a two prong which is the CTC sensor.

I know that on my W124 the two prong CTC sensor controls the output onto the cluster, but have heard that the single prong sensor OR even the three prong sensor controls it on other models.

Can anyone shed some light on what sensor I should be investigating/replacing OR how to test it first.

Everthing else works fine on the cluster.

Thanks.

[ps2cho]

The four prong is for the CIS. The two prong is for the cluster. That is the one that may need replacing.

[Arthur Dalton]

Originally Posted by ps2cho

The four prong is for the CIS. The two prong is for the cluster. That is the one that may need replacing.

The single wire sensor is Gauge sender/thermistor.

http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=2AO123CS42DT0ZJ8TA&year=1992&make=MB&model=400-SE-001&category=P&part=Water+Temperature+Sender

The 2 prong/wire is ACC panel input and has nothing to do with the temp gauge.

Here is the test specs for the temp sensor/thermistor:

http://www.peachparts.com/shopforum/showthread.php?t=179192&highlight=temp+ohms