Jaguar Repair: 1987 XJ 40 3.6, regulator problem, xj 40

Question
Hi Please help my jaguar has the red light on all the time but the alt is charging just over I've  two lines over 13 on the gauge..
Thanks Danny

Answer
Hi Danny,
The 40 series didn't come here until 88 and I have no experience on them. However, the charging system is like earlier models I think.

You need to put a volt meter across the battery posts and read battery voltage (12.5+) and start the engine and set the RPM on about 1500 RPM and read the volt meter. It should read from 13.8 to 14.5 volts but no more. If it does that ok and the charge light is on all the time even with the key off then pull the small wires off of the alternator and note if the light goes off. If that is the case then you have either a leaking diode pack in the alternator or a regulator problem and need to either replace the alternator of have it repaired. If it charges more than 14.5 it is also bad. If when you pull the wires off of the alternator and the light stays on you have a wiring problem.
Howard