XJ needs to be moved after 20 years... help please

[Wiggles (Paul Wigton)]

Cedric, your memory is excellent!

Behind dash "voltage regulator"

The IVR “regulates” the input (battery) voltage, which can vary between, say 10V and 15V depending on load. The regulated output is a constant 10V (pulse width modulated). Thus the fuel and temp gauges, set up to expect a 10V power source, are accurate independent of the battery voltage. It’s not that the oil pressure gauge isn’t considered as important, but rather that the OP system contains its own voltage regulator. Operation is quite similar to the IVR in fact, except that the regulator it…