Why Won't My Temp Gauge Work?

[2052006 10]

Had a couple of little things to do on the car today:

 

Check the wiring to the starter motor and condition of brown multiplug due to developing the occasional instance of not starting (ie starter motor not even turning for the first for tries and no, it is not the solenoid). All seemed ok, just cleaned the connections on the starter.

 

Then I had to drop a couple of litres of coolant out to add some more anti-freeze for the winter as I have been running it without much a/f in since changing the engine in the Spring.

 

All was fine, the multiplug seems pretty good (thoroughly cleaned during the conversion anyway).

 

So, ran it up to temp BUT the temp gauge now wasn't working. Have never had a problem with it before. All other gauges work and so does the STOP and warning lights on the pressure and temp gauges.

 

Am I right in saying the that the two sensors behind the thermostat on the rear on the engine (one protruding more than the other) are responsible for the gauge? Checked the brown multiplug wiring (again) and have even swapped both sensors for known good ones. Still nothing

 

Any ideas please?!!

[jackherer 543]

Am I right in saying the that the two sensors behind the thermostat on the rear on the engine (one protruding more than the other) are responsible for the gauge?

 

One is a sender for the gauge and the other is a switch for the warning light.

 

Try unplugging the wire from the sensor and grounding it, the gauge should read maximum when you do this (or the warning light will come on if you unplug the wrong one). If it does nothing try grounding it at the brown multiplug, if that does nothing find the relevant pin on the brown multiplug under the dash and ground that.

 

Then I had to drop a couple of litres of coolant out to add some more anti-freeze for the winter as I have been running it without much a/f in since changing the engine in the Spring.

 

Its important to run a 50:50 mix all year round because the coolant/antifreeze is a corrosion inhibitor too, this is especially important with an all alloy engine.

[2052006 10]

OK, thanks very much.

 

I have found out that there is a fault in the wiring between the multiplug in the engine bay and the multi plug under the dash - as your suggestion about grounding the wire worked from under the dash but not from the engine (ie. other end of the wire from under the dash). So hopefully I'll be able to find the fault in the wiring now.

 

However, I still need to know which sensor is which. One is slightly larger (protrudes more) than the other. Disconnecting both of them doesn't cause the warning light to go on. Are you sure disconnecting the warning sensor would cause the light to come on?

[jackherer 543]

The warning light will come on when you ground the wire that was plugged into the sender, not when you unplug it, sorry, I didn't make myself clear.

[2052006 10]

Cheers, that makes sense. I have fixed it now - the gauge wire had a minute hole in the insulation just after the multiplug and the wire had corroded inside. Made up another wire and bypassed the multiplug crap. I think the warning light one was ok, but made up another one for that too. Bit of a bodge, but better than before and it works a treat now. Just need a soldering iron and learn how to solder now. I think the car would benefit from getting rid of the multiplug altogether.

 

Any preferred methods / different connections or is it a case of simply soldering the wires together?

 

Cheers for the help anyway.

[jackherer 543]

Solder with heatshrink or similar to protect it is fine, or alternatively you can spend a few £££ on a modern waterproof multiplug and a crimptool to match.