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Date Name Message
09/12/2002 14:13:01   Steve H   I seem to have an electrical problem with my temperature gauge that I can't get my head round. It works fine however whenever an electrical devise is switched on it reads higher. This could be brake lights, indicators make it sway back and forth and head lights send it into the red. Dangerously I have taken to ignoring it and relying on the oil temp gauge (I have a custom dashboard). Logic says it is the earth to the gauge but I have checked this and it isn't. Of course switching on the lights would lower the voltage across the system but if anything, this should make the gauge go down. (less voltage - less current - less reading) The unit is a replacement white needle one from highgates after the previous one had a dancing needle due to a completly useless earth contact within the gauge.
Before I go taking the gauge apart and testing things with a muilt meter, has anyone any suggestions?  
10/12/2002 08:51:54   Alec   Hi Steve,

This is a very common problem on V4's. It is down to poor contacts and can lead to strange temperature readings. sometimes it can look like the car is nearly overheating when it is actually at normal temperature.
You should find an earth connection onto the bar underneath the dashboard. Take this off and clean it very well and put back. This will hopefully sort the problem, if not you need to remove the connections to the back of the unit and clean. It can sometimes be an internal connection fault also within the guage.
Generally it is a combination of losts of small losses through many connections that causes this.  
10/12/2002 13:48:13   Steve H   Thanks Alec. I have tried under dash bar contact and it doesnt seem to be this. (I have even tried jumping an earth direct to the earth terminal on the back of the gauge). It looks like it must be an internal contact. Surgery time!  
04/01/2003 12:27:40   Senor Burtold de Cokain   Try the fuses. I had a similar problem with the fula gauge on my 95. It turned out that the fuse which supplied power to the whole gauge wasn't contacting and the power was feeding through other systems causing the reading to flutuate depending on what electrical devices were pulling power.  
05/01/2003 18:49:51   Alec   That is a good general point too. The fuses cause all sorts of other problems. I trash mine every now and again, clean all the contacts in the box and then fit new fuses.  

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