A while back my back-up alarm distance sensors began to malfunction. I wonder if there is a diagnostic procedure for these as I see for many other vehicles.

Conditions:

Upon selecting reverse, I get a steady tone for about 5 seconds followed by silence. The alarm is effectively dead until I restart the car and get the same malfunction.

Thoughts:

Seems like one of the sensors might be shorted and in need of an accoustic repair (a.k.a calibrated thump) or replacement.

Please advise.

Bob

 

There's quite a lot about this on the Forum.
Here's a useful diagnostic from Graham
https://www.jaguarforums.com/forum/x...problem-69117/
also
If you turn the ignition on, not running, and apply park brake. Put car in reverse and you should be able to hear the sensors clicking if you put your ear up to them. It is a sonic sensor. Some people can hear it, others cannot. However, if your reverse aid system is inop, you probably wont hear anything.
and the wiring harness to the sensors can frequently go bad.

 

Yup, if its not clickin, its not working. Mine acted up months after.a bumper respray, the body shop bent a pin on the connector when reinstalling a sensor. Might be an easy fix. Careful, they are fragile.

 

+1

It's usually the sensors.

The system is quite straightforward but your XJ differs slightly from the thread Steve linked for you which was aimed at the XK8. The modules are a different design and location. Here's the Parts Manual diagram showing all the components:



If it doesn't turn out to be sensors, trace the harness from the module (item 1) which will be concealed behind the luggage compartment trim back to the power feed an on to each sensor.

Graham