Hi we just found an 1986 xjsc v12 jag in a garage that has been sitting for 15 years with 46k miles . Great body inside and out. A little wax and the car a really new I have 2 questions. I changed all the belts flushed everything and everything runs brand new. But. My instrument panel works except the 4 middle gauges. The fuel heat oil and temp. They do not move. Any quick fix ideas? Also. Under the dash directly under the swearing wheel there are two knobs. One is for the instrument brightness that is a bIgger round know by my right leg. But there is another round know above my left leg. And when i turnit off nothing happens but when's turn it on the two lights red and yellow on top,of instruments beep and blink once. What is that knob? Thanks for your help.
The Fuel, Temp, Oil, Volts, Tach and speedo are all powered from one source. Fuse #4 on the main fuse panel. They all share a common ground but have their own individual senders to operate each one. If any one of these gauges works then the power supply is not the problem and neither is the ground the problem. If any one of the gauges works then you need to check the harness plug connectors.
I don't remember two knobs under the dash. Passably a odometer reset?