I sold this car to a good friend and this problem immediately started happening. Never happened to me during the year that I owned it. The car runs perfectly, starts readily, smooth idle, smooth on the highway, etc. About every 1/3 time, however, turn the ignition key to off, and the engine keeps running, Take the key out, shut and lock the door, and the engine keeps running. It will eventually quit, usually after a minute or so.

The electrical system in this car is very clean, and I've made it cleaner by removing every fuse, hitting the contacts with contact cleaner, and reinstalling the fuses. The only corrosion that I found was on a ground post located under the air filter box. I cleaned that along with the terminals using a Dremel wire brush, installed new stainless serrated washers between each terminal, reassembled and torqued it down and applied rust-preventive. Did not solve the problem.

Next I put a new ignition switch in. Rock Auto had the part for about $60. Identical to the original. Did not fix the problem.

I do not have an electrical diagram for the car. My Haynes Manual for it is for earlier models. Is there a relay in the system that I am not finding?

 

Gus will have the electrical guide on his site.

JagRepair.com - Jaguar Repair Information Resource

 

Thanks. The Electrical Guide shows a "ignition coil relay" under the bonnet on the right side, in front of the fuse panel. I'll have the owner check that.

 

Hi Yadkin,

I believe that Ignition Coil Relay may only be used on the V12 cars.

One possible suspect is the ECM Controlled Relay, since it provides B+ power to the ECM, fuel injectors, ignition coils and other components. It does not power the fuel pump, but if its contacts failed to release when the ignition was switched off, the engine might continue to run until the fuel pressure held in the rail by the fuel pressure regulator falls to the point that the fuel lacks the stored energy to squirt through the injectors as they open.

The ECM Controlled Relay is in the right-hand engine bay area:



It might be worth swapping one of the identical but less-important relays for the ECM Controlled Relay to see if the run-on is resolved.

Cheers,

Don

 

Hi all thought I’d bring this back up as I have similar problem. So first I’ve been working on front suspension and replaced all bushes. Anyway after doing that car had an intermittent no start. Cranked fine but felt like no fuel supply. After lots of cracking it would start. I filled the car up and that seemed to fix no start problem? Now I have a won’t stop problem. Take key out of vehicle and engine keeps running. I’ve replaced the relays in the engine bay front and rear right footwell but still occasional no stop. I’ve disconnected the battery and re connected. When the car won’t stop I pull the ignition fuse and it stops. Then when I restart it takes a few revolutions to start again. If it stops properly with the key the. When re starting it starts instantly . Anyone got any ideas? Seems like a stuck relay but not certain which other one it could be?

 

Check the ignition switch in the column?

 

There is a 2nd power source to the ECU that is controlled by the ECU and brings power back into it

This is the large right # 5 relay and it can be swapped with a headlight relay or one of the same part #

You can tap on it to see if that resolves a run on engine

The ignition coil relay is only used on the V12

The ignition switch connector is easy to get to but gets confusing as more then one contact is closed for each key position

With the key in the off position the right engine bay fuse box relay should not click in your fingers as you remove and reinstall the relay into the relay socket

this would test the ignition switch but not the relay in your fingers using as a tool ( you are relying on the relay to freely operate correctly and communicate to you )

This relay called the ignition positive relay ( there are 2 called this on the car ) is the 1st power to the ECU

 

Hi Parker thanks for you advice - do you have any pictures of the locations of these relays. Do you know which circuit is shut down when the ignition key is swtched off?

Matt

 

Don B had this pic on a different post for a different issue





The ignition switch provides a ground path to car frame to close the "King "relays in the corners of you fuse boxes , one of them is the ignition positive relay and not the large ECU controlled relay which bring power back into and is your 2nd power to the ECU

The car frame ground wire is pin 5

The way it should work in the key run position pin 3 should close to pin 5

More then one pin closes to pin 5 in the different key rotation positions at the same time so it can be confusing

Your problem is a ground path is provided when not supposed to or the ignition positive relay is " floating "

You can swap this right engine bay fuse box relay with the left engine bay fuse box as in reality only runs the car horn

Most of the fuses in the fuse boxes do not rely on the : King " relay to close but bypasses it and hot at all times

This connector can get contaminated with fluids and corroded

Easy to get to with the 2 screws on the U shaped bottom of the steering column cover

The car side half of the connector lifts straight up to be able to pull it out to you for easier access

The ignition switch itself is attached to the key barrel and can be removed by the 2 small set screws on the switch;s ears

The same part # for the ignition switch is used on the later V8 powered Jaguar X308 4 door and X100 sports car , You don't need a new key as you leave your key barrel alone

Still editing

 

Hi further diagnisos info.

So if the drivers door is shut when I turn off the key and remove the key the engine shuts off. If the door is open and I turn off the engine keeps running until I shut the door and then the engine shuts off? Of note when the engine keeps running with the door open the lights warning light is on.

Does this make any sense to anyone?

 

 

You are in Australia ?

There is a hard reset of the security lock control unit

Do you have the original stereo control; head security code ?

 

Hi yes in Australia. Car does not have original radio. I have now found that if any door is open car does not stop. Shut the open door and car stops. The ecu control relay remains powered until the doors are shut? Thoughts?

 

Further info - take out fuse 8 in right hand heel board fuse box (interior light) and all is good again. Therefore would I be correct in suspecting the that there is a wiring issue between the positive for the interior lights and the ignition keeping the relay open? Any thoughts on where this might be?

 

Thinking during a day for different chores

A hard reset can be done on the SLCU since you don't have the original stereo head ( this is a anti - theft feature if someone disconnected your stereo head which is bothered with in a hard reset )

The hard reset is more then just removing the positive battery cable for a period of time

 

Ok All I may have solved this and this info may be useful for others who have had this probelm with no solution. I have tracked down the issue to the puddle lights (In door lowers) and found foist that removing the interior lights fuse solved the problem so next I have removed the Puddle Light relay and replaced same with a new one and repalced the fuse and the issue is gone. Put the old rleay back in again and hey presto no stop issue returns.

Dont know whether this means there is a problem with my BCM but somehow seems that the stuck puddle light circuit (relay seemed stuck closed -fused contacts I would suspect) kept the ECM Relay active. Now that relay is operating correctly and shutting of the engine. Anyone ever come accross this before ?? Maybe it is just my car ??

 

Bad diode across the relay coil??