Lights on - temp guage goes up

neilc

neilc

Member
I have had my car for about a month and today, as it was dull and wet, was the first time I drove in the day time with lights on and I noticed the temp was reading higher than usual. I turned the lights off and the temp guage dropped back. I turned the blower and hrw on to put load on the alternator - no movement. Lights on again - back up. The bulb in the instrument that lights petrol and temp guage needs replacing, so I had never noticed this at night before. Could it possibley be current that should be feeding the instrument bulb shorting to the temp guage?

Thanks for any tips!

Neil
 
The instruments run from a regulated supply, hence putting the heater on etc has no effect, I suspect the reason putting the lights on has an effect is due to the instrument lights being fed from the same supply. (I could be wrong), try turning the instrument dimmer right down and see if that has an effect.
 
The first impression I get from that symptom is that the panel is not earthing properly; the panel lights are getting 'earthed' via the regulator heating element, through the temp gauge, and then the temp transmitter under the bonnet.

It may not be the problem, but that is my first impression.
 
I agree re earthing. I'd be inclined to start by pulling the instrument cluster forward and start by making sure the individual instruments are properly seated in the circuit board, then have a look at the earth strap. If you feel you need better access, take the top shroud off - just remove the A post covers and then you can get to the fixings. The P6 is fundamentally a very simple mechanno set, so if you have difficulty getting at anything it means there's a bit you haven't removed first!

Chris
 
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