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Billy, Trainer/ Master Technician
Category: Jaguar
Satisfied Customers: 3498
Experience:  Trainer 8+ years, master tech. 10+ years, SAE member
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Cant get any life on my 1991 Jaguar XJS to start it. Battery

Customer Question

Can't get any life on my 1991 Jaguar XJS to start it. Battery fully charged but seems as if there is an isolator switch preventing starting. Any advise to get it going?
Submitted: 4 years ago.
Category: Jaguar
Expert:  Shantal-Mod replied 4 years ago.


I've been working hard to find a Professional to assist you with your question, but sometimes finding the right Professional can take a little longer than expected.

I wonder whether you're ok with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, feel free to let me know and I will cancel this question for you.

Thank you,


Customer: replied 4 years ago.

Keep trying



Expert:  Shantal-Mod replied 4 years ago.

Hello Edward,

Thanks for getting back to me. We will continue to look for a Professional to assist you.

Thank you for your patience,


Expert:  Billy replied 4 years ago.
Hello Edward and welcome! I'm Billy and i will assist you with this.

My apologies for the delay, thank you for your patience.

Hold the ignition in the "start" position for 5 seconds to enable the starter to operate. If this fails to start the vehicle, repeat theprocedure.The back-up battery will recharge from the vehicles main battery, which will be charged from the vehicle charging system.The alarm system must also be recoded by pressing both the remote transmitter buttons a total of five times for both units.

Get back to me with your results, or if further assistance is needed.

Regards, Billy
Customer: replied 4 years ago.

I don't have a remote transmitter to recode the alarm. Any way around that?

Customer: replied 4 years ago.

Tried your procedure.....nothing happened.




Expert:  Billy replied 4 years ago.
Hello Edward,

This needs some major diagnostic procedure as If an alarm system fault exists and it cannot be traced using the alarm system diagnostic procedure, it is possibleto test the input/output signals to the alarm control module using a digital volt-ohmeter.
So you need to check pin by pin and here are the values (the cleanest copy i could find, since this is an older model):

Get back to me with your findings...

REgards, Billy