Temperature gauge and fan switch relationship

[White230CE]

Hi all,

I recently replaced the three-pin fan switch on my 230CE because the fan wasn't kicking in, and the engine temp rose beyond 80-90. The temp gauge was obviously working at this time. The new fan switch sorted the overheaing problem, but the temp gauge now doesn't work.

Question: Does the temp gauge work off the 3-pin fan switch, or is it merely a coincidence that it stopped working after I changed the fan switch? I ask because there is a two-pin thingy next to the fan switch, where one pin has broken off, and I'm wondering if it is this two-pin thingy which controls the temperature gauge. Trouble is, I can't remember if it was already broken before I changed the fan switch.

Thanks

 

[djb]

temp sensor is usually mounted onthe engine, as it shows engine water temp. If mounted with fan switch would show rad temp, ie cold most of the time. so I think you have perhaps accicentaly knocked the temp sensor, but it is not near the changed fan switch.

others will advise more accurately as to actual position.

 

[television]

All of the sensors sit on top front, as it the hottest part of the engine, what is the engine and year or the car

 

[White230CE]

Hi Malcolm,

It's a 1991 model.

Cheers

Ray

 

[White230CE]

It's a 1991 W124 230CE with the M102 2.3 litre engine.

 

[television]

The coolant temp sender has 2 or 4 contacts dependent on the ignition system, it sits just behind the fan sensor/switch or the middle one of the 3

 

[White230CE]

That description matches the appearance and location of the broken two-pin thingy I mentioned earlier!

Thanks Malcolm. I'll go shopping for a coolant temp sender and see if that resurrects my dash temp gauge. Will report back.

Ray

 

[The Crooner]

The four pin sensor is critical to the operation of the engine, one signal goes to the fuel injection, another to the ignition.

 

[television]

The four pin sensor is critical to the operation of the engine, one signal goes to the fuel injection, another to the ignition.

Yes that right, I cant recall ever having a 4 pin one fail or being mentioned before.

 

[The Crooner]

Which means that the three pin sensor is the one which powers the water temperature gauge, one pin for that, the pair for the fan motor - easily shown by shorting the pair with hands well away from the fan.

 

[television]

Which means that the three pin sensor is the one which powers the water temperature gauge, one pin for that, the pair for the fan motor - easily shown by shorting the pair with hands well away from the fan.

The electric fan sensor is separate usually from this sensor and the one on top and the one nearest the rad is the one for the fan

 

[White230CE]

Hi Crooner,

When you say one pin on the three pin sensor powers the water temperature gauge, do you mean that that pin is the coolant temperature sender which operates the temperature gauge on the dash, and the broken two pin thingy is not?

I ask because I've changed the three pin sensor twice. The first change was because the fan wasn't kicking in and it was done by a friend using a reconditioned sensor. After this first change, the fan worked, but the temperature gauge on the dash did not. He told me the sensor was faulty and advised me to get another one. I did so (brand new from GSF) and did the second change myself. The fan continues to work after the second change but the gauge remains dead. Could it be that I have had two successive faulty 3-pin sensors?

Thanks

 

[White230CE]

Problem solved

An update for anyone who's interested.

The three pin fan switch does operate the temperature gauge on the dash. The gsf part I bought new must have been faulty or somehow unsuitable, because I put in a new genuine Merc part yesterday and the temp gauge finally came to life.

The two pin thingy previously referred to is apparently to do with the fuel injection, according to the Merc dealer's parts department.

Thanks to all.