XJ Rear parking sensors

[GilesS3]

This might sound like a really stupid question, but will the rear parking sensors not work if they are painted over?
I bought an 04 XJ with only 40K on the clock and full history to go back and forth to work, and am very pleased with it. But when you select reverse, the light overhead comes on, I get a continous beep for about 3 seconds (as though I am rerally close to something), then it shuts off. The bumber was painted for me as there were some scratches on it. The front ones are fine.
Any suggestions??

[piquet]

GilesS3 said:

This might sound like a really stupid question, but will the rear parking sensors not work if they are painted over?
I bought an 04 XJ with only 40K on the clock and full history to go back and forth to work, and am very pleased with it. But when you select reverse, the light overhead comes on, I get a continous beep for about 3 seconds (as though I am rerally close to something), then it shuts off. The bumber was painted for me as there were some scratches on it. The front ones are fine.
Any suggestions??

i'm sure someone who really knows what they're talking about will be along soon, but from memory i'm pretty sure i've had this happen

the light comes on and you get the continual alarm because the sensors aren't working, usually it's only one but because it can;t do the job it just shuts down, you normally just replace the duff sensor. I guess they may not have connected one up again

they also go if water gets under the paint, that causes the paint to bubble up, if you wet and dry the paint off it fixes this

[darky32]

The constant tone you are getting is an error tone indicating something isn't working correctly on the system, It could be that there is too much paint on the sensors but something I have rarely seen, Here is something you can try:

With the engine off but with the ignition on select reverse(make sure the handbrake is on if not on level ground) after you hear the error tone go to the back of the car and gently touch the sensors in turn, if working correctly you should be able to feel a gentle pulsing from the sensors, check all the sensors and if you can feel one sensor that has no pulse then that will be your faulty sensor!
If you dont feel any pulsing at all from any of the sensors it may be the control module in the boot that is faulty or a wiring fault in the bumper harness.

A dealer should be able to datalog the sensors and tell you what is/isn't working within 30 mins

Hope this helps

[cml]

Funnily enough my father recently bashed his rear sensors in an otherwise harmless parking 'incident'. the replacements were black (some mix-up). The chap at the local garage, who is pretty good, said that you can paint with a dab of touch-up but you have to be very careful to only put the thinest of layers on, and possibly polish it down otherwise it will indeed stop them working.

[jimattfield]

Loads of cr*p get under the bumper where the sensors are. The connectors on the sensors get corroded and/or loose. When the rear-parking controller loses connection to one of more it just puts out a 5-second tone before shutting down. Removing them all, cleaning them and using contact cleaner cured my XJR of exactly the symptom you have. Could also be a stone-cut wire to a sensor.

Jim

[rswift]

You might find simply carefully cleaning, sponge etc will do the job, they get all sorts of crap in winter. Also there is a dangerous method, depending if you have a trustworthy mate.

Stick it in reverse, with a mate/mrs with their foot firmly on the brake pedal. Then listen very carefully (ear next to all of the sensors) in turn. You should hear a clicking from all but the faulty one.

The above is from memory, but have a look on the excellent Jaguarforum.co.uk, lots of stuff about parking sensors, same on X & S types.

In the short term you can press the button on the overhead console to switch off the sensors.

[GilesS3]

Thank you all for your responses. I took the car to the local Jaguar dealer and they confirmed that two of the sensors have failed and need replacing. The mechanic took me out to the workshop and explained how to check the sensors (for future reference), and there are two ways (as outlined by previous posters). Put your ear to the sensor with the ignition on and reverse selected (engine off obviously!!) and you can hear a faint ticking noise if sensor working properly, and you can also feel a faint pulse with your finger held close to the sensor.
So both of you were right!! The downside is the bumper has to come off ansd the new sensors painted!! Never mind, at least it is cheaper than reversing into something!!

thank you all for your help and comments.