[Vwdiesel] VW instrument cluster problem

Roger Brown r.c.brown at ieee.org
Sat Nov 22 14:19:10 PST 2008

Caleb Van Dyke wrote:
> I have a 1981 Rabbit pick-up with the diesel, and I am having a strange problem with my temperature and gas gauges. Every so often, the temperature reads about 3 notches higher, as well as the gas gauge. Then, for no apparent reason, goes back to where it was. This has me wondering if there is a loose connection somewhere, a voltage imbalance or surge, or ???
> I have noticed in my Haynes manual that in 1982 VW put some sort of a voltage controller in their dashes. I do not see this on my dash set-up, so I'm assuming it wasn't avaiable in '81.
> Thanks for any help.
> Caleb

Should be a voltage stabilizer or regulator on all clusters with gauges.  Why?  Gauges 
work by putting a known (i.e. regulated) voltage across the variable resistance of the 
sender and the resultant current is what drives the meter to give you a reading.  If no 
stabilizer, you would have anywhere from 12 volts to 14 volts across the sender and gauge 
and +/- 10% reading on the gauge depending on what voltage your system was running at.

The stabilizer is the little 3-legged transistor looking thing on the far left center of 
the image below:
Regulates the cluster voltage to around 10 volts as I recall.



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