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[VX1]

Hello guy's,

Well my temp gauge stopped working for no reason. Now I have tried disconnecting the battery for a while then reconnect, didn't work, tried a wire direct to the loom connection behind the dash clocks, nothing, tried earthing the gauge to see if anything happens, nothing, tried two other known good clocks again nothing. I am now at a loss of what to try next so hoping someone on here could help.

Thanks in advance
Paul

[TheBoy]

Have you checked the obvious, that the spade connector is still on the sensor?

[VX1]

Yep, the spade connector is on tightly. There is a connection all the way to the multiplug to the clocks but still no temp gauge.

[Andy B]

Yep, the spade connector is on tightly. There is a connection all the way to the multiplug to the clocks but still no temp gauge.

What happens when you earth the cable that goes to the sensor? :-/
It should read fully hot.

[VX1]

Nothing, tried it. The funny thing is there is power, if you like, going all the way throughthe loom to the dash clock's, also I have used two known good dash clocks as well and still nothing.

[Andy B]

Nothing, tried it. The funny thing is there is power, if you like, going all the way throughthe loom to the dash clock's, also I have used two known good dash clocks as well and still nothing.

I'm out of any more suggestions then I'm afraid.   

[Dave DND]

check continuity then from the connection at the clocks to the pin of the gauge.

Starting to see quite a few cars now 10+ years old with print failure on the pcb of the clocks. Merc and BMW being the worst.

[feeutfo]

Duf sensor?

[TheBoy]

Duf sensor?

Already disproved by grounding sensor wire.

Sounds like continuity between sensor and gauge. Worth checking the dash is fully seated, as I've seen that affect it before

[VX1]

I have tried all the suggestions you have all made and it doesn't make any difference at all. I am going to change the coolant bridge incase this is affecting the sensor, it's worth trying to rule that out. I need to get to the bottom of this as it's driving me nuts and want to keep an eye on the temperature in case I get an overheating problem.

[TheBoy]

have you checked continuity from sensor to connector behind dash?

[VX1]

yes, everything is all ok.

[TheBoy]

Hmmmm, interesting.

The connector behind the dash, does this look like the temp connector is sufficiently 'bent out' to make connection with clocks panel?

You have proved its not the sensor (by shorting sensor wire to 0v), proved continuity from sensor wire to dash connector, and tried with known working clocks (from same era?, as they do vary)

[VX1]

Yes everything is all ok behind the clocks and yes the known other clocks are from the same era and identical model. The other thing I am going to try is different washers for the coolant bridge as I think the washers that are on there could be copper washer with the rubber inners.

[Kevin Wood]

The sensor ground connection is via the engine, IIRC, so you might have a problem with a grounding strap between the engine and body or body and battery perhaps? It would only take a little resistance to upset the reading. Worth checking the straps.

Also, measure the resistance between the pin on the sensor and a suitable point on the engine (scratch an area clean of corrosion on the coolant bridge, for example). It should probably be in the hundreds of ohms region although I don't know specific values for this sensor. At a wild guess I'd say perhaps 500-1000 ohms cold decreasing to a couple of hundred when hot.

Might be something useful in TIS or the Haynes manual about expected resistances?

Kevin