Parking sensors

[markjuby]

I would be grateful for some guidance please.

The parking sensors have suddenly failed on my 2002 XJ8 Exec 3.2L . When reverse is selected there is a constant tone from the sensors, and then nothing. Neither the side nor the rear facing sensors provide any indication of approaching obstacles.

Having read previous posts I have checked the connectors to the 4 sensors and they seem to be in order. I have traced the wiring loom back to the "magic box" in the boot, and can find no break in the wiring.

My thinking is that since it emits the constant tone, it cannot be the fuse. As there is no response from any of the sensors, it is unlikely that all 4 failed at once, so it must be the "magic box". My module is numbered LNF 7352 AA.

Is this right, and is my only option to replace the unit? Perhaps more likely - what have I missed?

Thanks for your help. It is always appreciated.

Mark

[ptjs1]

Mark,

See if you can hear each sensor working. They each emit a very small ticking sound when functioning. Put your ear very close to each one. Be careful when checking the rear ones. I think, from memory, that you can do it with ignition on and in reverse, but engine not running.

This can be a very easy way to find a non-functioning sensor, which may be the cause of the problem.

Good luck

Paul

[markjuby]

Paul, thank you for that. I have now checked the sensors, and you are right. One of them is not making a clicking sound.

I will try replacing this unit and see if that does the trick.

Mark

[daveji]

There is another post somewhere about this issue.
The steady tone is a "warn tone" to indicate that the reverse park system
has failed its self test and is non-operational.
I am just replacing the second failed sensor on my XK8
The Jag part replacement is about £50 + vat from Barratts.

[markjuby]

Thanks to both Paul and Dave.

The replacement sensor arrived this morning. Popped it in and hey presto we are back in business.

Mark

[ptjs1]

Good to hear, Mark!

Well done

Paul

[RichardSEL]

My reverse park sensor system doesn't produce any sound. But I'm told that the sensors are giving out clicks. Although I couldn't hear any. And that means that "the module should be OK."

And not fully knowing the history (three owners) wouldn't surprise me if, like as described earlier in this thread, the speaker's been unplugged or lead cut coz one or more of the sensors are faulty.

So was wondering how to reach the speaker that's underneath the parcel shelf?

[J44EAG]

As always, a diagnostic tool will point you towards which sensor or other part of the system is playing up. Only by diagnosing can a correct plan be put in place to avoid unnecessary part spends.

Mike.