Hi guys, so my 95 xj6 has decided it doesn’t want to run anymore, I suspect it’s an alarm /immobiliser problem as I can hear the alarm quietly burbling away, I’m getting a spark and fuel but no fire!! Unfortunately the key fob no longer works, and the key doesn’t lock the doors manually either, on my other xj6’s this doesn’t seem to matter, as turning the key to first click in ignition turns the alarm off, but doesn’t seem to work with this car!! Any ideas!?! Uk car, cheers, Shane.

 

I'm assuming you get starter rotation which shows no Security / BPM immobilization

 

Yes, the car was running perfectly before, but not in regular use. Last time I went to start it it wouldn’t take, I then noticed very quiet crackling and burbling from the alarm and wondered if it had something to do with it.

 

See this thread on post # 10 and see if like :

https://www.jaguarforums.com/forum/x...n_dance-disco:

 

Are you sure you have spark and fuel, and did the starter turn at all, and did you see the engine warning light lit up before cranking?
Was it the sound from the starter rather than from the security system? Is the battery strong enough to turn the starter?
In theory, when the immobiliser is activated, the fuel system is cut off and the starter is deactivated, and you won't see the engine light before cranking.
Also, as far as we know, only UK X300s and those in Hong Kong (both Right Hand Drive regions) are fitted with the immobiliser.
Also you wish to read this thread "alarm system hard reset" to see if this would clear your alarm flag, and if indeed it is the alarm preventing the car to start.
If all endeavours fail, and you are sure that the immobiliser is indeed the culprit (it was to my XJR "Rose" - long story here) you can contact forum member "XJREngineer" (Andy) to see if he can write you a special ECU to bypass the immobiliser upon engine start-up.

 

It is cranking, I do have a light, and the sound is definitely from the alarm, I do have fuel and a spark. I’m starting to think from what your saying that I may have two separate issues!!!

 

The sounds from the alarm system can be from low voltage

See the pic above on the instrument cluster volt meter and watch during starter rotation

It should not go below 11.4 volts during the natural starter sag

 

I’ll check that but its a good battery I was using, the one from my other xj which always starts that car with no problems.

 

Remember to never install the battery backwards

Ask me how I know

You can read for the 11.4 volts with a hand held meter on the RH engine fuse box large terminal post

This is where the engine ECU gets its first power on fuse # 12 / 10 amp

The second power comes from the large ECU controlled relay which brings another source of power back into the ECU and also power for the fuel injectors to open in their timed sequence

If there is a large sag like to 9 volts it will be easy to see on the instrument gauge

 

So, got her running today!! Turns out it was the alternator starting to seize and not letting the car crank over fast enough to start (first time I’ve tried to get it running for a while!!) so loosened the alternator belt, some easy start into the throttle body and away she went. Turns out the alarm crackling was down to a bad connection!!