Jaguar Repair: 1984 XJ6 Will not start., power resistor, resistor pack

Question
My 84 XJ6 will not start.. I have tested the fuel pump, good spark, tested relays on firewall (diode, main and pump)but injectors are not firing. I put in another ECU and nothing happening. I suspect the Power Resistor. Can this be tested? I also have a new amplifier but that did not make a difference either. Pick-up is working fine.

While driving the car stopped running like pulling a plug and would not start. The first time it happened it started after a couple of hours. 2nd time I had to be towed home. I tinkered with it a while and put a new coolant sensor in and it started. Thought I had it fixed. Drove to work and it would not start. After an hour in the freezing cold moving and shaking parts and wires it started and I got home. Has not started since. So now I am suspecting the Power Resistor. What do you think?

I look forward to your input.
Thanks,
Chris

Answer
Hi Chris,
If you mean the injector resistor pack all you need to do is check for power on one side of the injector plug.
An odd thing with the series III cars is the battery, so to test it just connect up a known good battery as a jumper battery as though you are jump starting a car with a dead battery even if the car battery is up. If the engine starts right up you need to test the charging rate (13.8 to 14.5 v) at the battery at a fast idle. If that is ok then you need to purchase a "Deep charge" battery like a diesel battery. The ser III can not run on a battery that is going down even if it spins the engine over fast.

If all of that is good you need to get a wiring diagram of the ECU connector and start testing wires as for what each does. A logic probe (available from Radio Shack) is the best tool for the job although a good volt meter will work. If you don't have a diagram let me know and I will put one on my web site for you to copy.
Let me know,
Howard