Club 80-90 Forums

Hello. My problem is that the red flashing light AND the temperature gauge both go haywire, together, at the same time, intermittently. The light will start flashing and the gauge will move right up to boiling. It might stay that way for 5 seconds or 5 minutes or much more. The radiator and the coolant sensors have both recently been changed. Thanks for your help.

There have been many posts on various failures of the temp gauge (and associated flashing light) so do take a look at those by using the search function;
Also there are various pages in the Wiki that cover the common reasons for this fault e.g.
https://club8090.co.uk/wiki/Co ... ht_on_dash

This is a pic of the system from that page;

So the needle shows hot when the temperature sensor resistance to ground is low ....

In your case it looks like the signal to the gauge from the temperature sensor is being "grounded" temporarily - grounding this signal wire will cause the temp needle to show full hot and the light to flash;
The trick will be finding out how this is occurring especially if it is an intermittent problem as you have suggested.
You say that you have recently changed the temperature sensor (this is the one in the engine bay not the one on the radiator? If that is the case then we can rule out that ......?
Which only then leaves the wire from the sensor to the gauge or the actual gauge itself ...... You might need to check the condition of the cable between the gauge and the sensor in the engine bay ....
(There is slim chance that it is the coolant level sensor relay playing up ..... I'd suggest pulling that out to see if that cures the problem ...... note that you'll then lose the low coolant level warning so proceed with caution while it is out)
Is this fault occurring often enough that you would be able to quickly see if pulling the relay fixes it?

great post mid life

kevtherev wrote:great post mid life

Thanks