Hi
Got a little problem with my 88 XJ40, I noticed yesterday that my instrument panel was all lit up (ie all digital gauges on and the self diagnostics panel diagnosing problems) needless to say that my battery was all but drained and would barely turn the motor let alone start it.

I had the battery on charge all nite and this morning went out and connected it, the car started beautifully as it always does..... however when I went to turn it off.... the motor kept running... even with the ignition in the off position and the key removed. I had to pull the HT lead from the distributor to kill the engine.... and got a nice zap in the process.

Any ideas why the engine will not turn off??

 

update:
after sitting here pondering what changes I had made to the car while trying to isolate problems, I remembered I placed a relay in a slot in the boot that was missing from the left quarter panel (grey relay ... cover says "Over Volts") I decided to remove it just to eliminate this as a cause as it was the only change I made prior....

So what is the "Over Volts" relay for and is it necessary for the vehicle?

Guess what..... dash lights and gauges are out and car turns off again.

 

An "Over Volts" relay is simply a relay to protect your electrics from power surges and the like.

In relation to the Jag, I can't give a precise answer but if you have a look at the electrical diagram you should be able to follow it to give you a little better understanding. Maybe have a look at the jaguar classic website for a diagram and part number.

Trunk Compartment Relay - Parts For XJ6 (2.9, 3.2, 3.6, 4.0) from (V)500001 to (V)667828 | Jaguar Classic Parts AU

or Jagbits - New and Used Jaguar Parts for XJ6, XJS, XJ8, XK8, S-TYPE and X-TYPE

or Motorcars Ltd - Jaguar Parts | Land Rover Parts | Mini Cooper Parts

It was obviously causing the issues you experienced for the previous owner(s) which is why it was removed. Or it may be possible that you replaced it with the wrong type of relay which then caused your issues. I'm not sure what the correct relay is for the "over volts' location.

I'm sorry I can't be any more helpful than this. I've been attending to my diff which has been giving me all manner or grief for the past 3 weeks...

 

p.s. be careful when playing around with the relays, especially the ones in the trunk as the mounting bracket is live...

If you accidentally touch the wrong relay prong in the wrong location it can seriously sizzle your electrics. Best to always disconnect the battery when working on or near it. I found this out the hard way!

 

Thanks for the advice Jagfix38,
I do tend to be careful when doing anything electronic on any car.
I always disconnect the negative lead before attempting anything....
Means a lot of disconnecting, trying to fix the issue, reconnecting, and re disconnecting if still not fixed until it works hehehe

A lot of **** farting around but well worth it when it all works