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My rear bumper parking sensor has suddenly started going off, usually with the continuous beep as soon as I select reverse, whether or not there is anything near me. Just started doing it a few days ago, for no apparent reason. Any ideas anyone?
Hi, I found the following information on the Road Fly forum - 2001 Jaguar XJ8 -
"I managed to get the "faulty" one out after your advice and have managed to sort the problem without it costing me a penny.
For the benefit of anyone else who might be having a problem here's what I did to trace the fault, which turned out to be a broken wire.
Symtoms - When selecting reverse I got a steady tone for about 7 secs then it would stop. The reversing tones did not work.
I have four sensors located on the rear bumper, 2 at the back and 1 on each corner.
I knew the module was ok as my garage had prevously tested it with one they knew was ok. The symtoms were the same but they didn't have time to look any further. The module is located in a pocket in the trunk fuse (breaker) box which is located to the right rear of the trunk. It just lifts out and the two multi-plugs easily clip off.
Test the sensors by switching the ignition on (engine off), (parking brake hard on & chock!) If you listen to each sensor in turn they make a quiet ticking noise if they are working ok.(An excellent tip from someone on this forum which I found on a search for info on my problem - Thanks!) You should be able to determine which one is not working as it will be quiet.
Next try swapping the quiet sensor with one you know to be ok. They pull out from behind the bumper if you lift the 2 plastic retaining lugs. They are a bit tight so they need a bit of a wiggle.
This should tell you if it is actually the sensor which is defective or whether there is a wiring fault. Make sure you wish hard for a wire because the sensor is £67 + Vat from Jaguar main dealer and they're not colour matched. You have to paint them yourself!
In my case all the sensors appeared to be working so I had to find the defective wire.
Each sensor is wired directly back to the module using 3 wires for each sensor. It is easy to find the defective wire by using a meter or circuit tester or similar. The colours at the sensor end match the colours at the module end.
In my case I found a broken wire behind the bumper where the loom feeds under a bracket toward the left side of the car before it enters the trunk. I had to separate the loom to find but once found I spliced it using a bullit connector before taping up the loom again after testing.
It seems a bit of a vulnerable point for the loom as on my car the loom was tight against the sharp bracket and it had eventually rubbed through breaking the wire."
You might possibility have a broken wire near any of the four reverse parking sensors.
Here are 2 JPEG images:
First one shows location of the Reverse Parking Aid Control Module:
The other is the Reverse Parking Aid System Wiring Diagram:
Here is a page from the 2001 Jaguar XJ Drivers (Owners) Handbook Supplement on the Reverse Parking Aid System:
Jim Lombardi
Last edited by jimlombardi; 09-21-2014 at 12:26 AM.
Hi, I found the following information on the Road Fly forum - 2001 Jaguar XJ8 -
"I managed to get the "faulty" one out after your advice and have managed to sort the problem without it costing me a penny.
For the benefit of anyone else who might be having a problem here's what I did to trace the fault, which turned out to be a broken wire.
Symtoms - When selecting reverse I got a steady tone for about 7 secs then it would stop. The reversing tones did not work.
I have four sensors located on the rear bumper, 2 at the back and 1 on each corner.
I knew the module was ok as my garage had prevously tested it with one they knew was ok. The symtoms were the same but they didn't have time to look any further. The module is located in a pocket in the trunk fuse (breaker) box which is located to the right rear of the trunk. It just lifts out and the two multi-plugs easily clip off.
Test the sensors by switching the ignition on (engine off), (parking brake hard on & chock!) If you listen to each sensor in turn they make a quiet ticking noise if they are working ok.(An excellent tip from someone on this forum which I found on a search for info on my problem - Thanks!) You should be able to determine which one is not working as it will be quiet.
Next try swapping the quiet sensor with one you know to be ok. They pull out from behind the bumper if you lift the 2 plastic retaining lugs. They are a bit tight so they need a bit of a wiggle.
This should tell you if it is actually the sensor which is defective or whether there is a wiring fault. Make sure you wish hard for a wire because the sensor is £67 + Vat from Jaguar main dealer and they're not colour matched. You have to paint them yourself!
In my case all the sensors appeared to be working so I had to find the defective wire.
Each sensor is wired directly back to the module using 3 wires for each sensor. It is easy to find the defective wire by using a meter or circuit tester or similar. The colours at the sensor end match the colours at the module end.
In my case I found a broken wire behind the bumper where the loom feeds under a bracket toward the left side of the car before it enters the trunk. I had to separate the loom to find but once found I spliced it using a bullit connector before taping up the loom again after testing.
It seems a bit of a vulnerable point for the loom as on my car the loom was tight against the sharp bracket and it had eventually rubbed through breaking the wire."
You might possibility have a broken wire near any of the four reverse parking sensors.
Here are 2 JPEG images:
First one shows location of the Reverse Parking Aid Control Module:
The other is the Reverse Parking Aid System Wiring Diagram:
Here is a page from the 2001 Jaguar XJ Drivers (Owners) Handbook Supplement on the Reverse Parking Aid System:
Jim Lombardi
Last edited by jimlombardi; 09-21-2014 at 12:26 AM.
Good stuff - thanks for the thread. My sensors stopped working all together (after intermittent working / not working). Didn't know where to start in the diagnosis.
Well, Have tried several times to find the cause of this problem, ably assisted by my ex Jag lecky/mechanic. Have tested wiring using meter, all seems to be ok, changed module, 2nd hand, no difference, mechanic says sensors ok (ticking) But lately, for some weeks, have been getting "Check rear Lights" warning on dash, when brake is pressed to allow gear selection from stop. This seems to happen only on start up after car has been parked for at least some minutes. Release brake and re-engage it and warning goes away, and stays away 'till next time car is parked, engine off, then re started. Are the 2 likely to be connected in some way?. Really getting on my nerves now. Been a yr since first appearing. Jim's advice was good but unfortunately didn't work in this case. Anybody else got any ideas?
Verdigris - The check rear lights I've had and the bulbs work, I polished the bulb contacts and bulb holder contacts with a solder pen/emery paper that fixed it, until one went and I just changed the lot. Same with the rear sensors, the amount of crap the loom and connectors collect under there means they could benefit from a remove - clean - refit, lots of wd40 to flush the connectors etc.
Just wanted to jump on this thread as I've been having an issue with the parking sensors in the XJR since I purchased it. Given that I've now knocked off the fuel pump issue, this one is next on the list. Same fault as usual, put the car in reverse, it beeps for 5-7 seconds and the sensors remain inoperative.
My car has no visible sensors in the bumper so I'm not 100% sure how the system actually 'senses' anything, but I digress. Working off of Jim's very handy diagrams (thanks so much for providing those), I located the module in the luggage compartment fuse box, however - I think I may have located the source of the problem right away. Jim says that there should be 2 multi-plugs connected to the unit - I have female ends for 2 multi-plugs, but only 1 visible connector plugged into the unit. I briefly attempted to trace the loom back upstream, but there does not appear to be a loose connector kicking around in the luggage compartment anywhere.
Does anyone have an idea of where to go from here? Your assistance, as always, is appreciated.
Hi David,
So yes, those sensors are controller by that little unit that can be found alongside the trunk fuse box. And yes, 2 wire bundles should be connected to it. There is a 3rd slot though, no idea what for but that's not the point ;-) So the sensors are visible on the bumper. My thoughts are that if you don't have the sensors, then ultimately you don't have the bundle set of wires from bumper sensors to the 'box'. I have no idea if the unit is in the car by default and only when the option was purchased (was it an option?) the bumper with sensors was installed and connected, then. Or, perhaps your car had it originally and the bumper got replaced overtime with a standard one? The fact you hear beep noise is a little spooky, but we all know our 'cats' have a soul.... BTW - I have these sensors on mine but they don't work. Never been a priority for me. Might try replacing that little box one day.
This is the module and the wires leading into it. There are no parking sensors in the bumper, and yet the car appears to be equipped with a reverse parking system.
I have just repaired mine the, loom had a previous repair on a cable, the broken cable I found was where the loom does a right angle through the floor panel, such a poor design and the rest of the loom is just under the carpet of the floor so taking the brunt of objects placed in the boot .... I have 2 tips to add to the repairs :-
1) The copper cables in the loom are of recycled copper not bright but almost black ! (I am an electrical engineer and have seen this a lot in automotive sector) to solder the broken cable needed a strong flux for the solder to flow. The flux in the the multi core was not strong enough nor was the the normal resin flux I have used for years ... but Plumbing flux worked brilliantly but use sparingly little is more !.
2) the tang on the connector for sensor is so small the plug can shake loose .. but by passing a small cable tie through the connector in front of the tang pushes it down making it a solid lock when pushed home ...
thanks for the above info it made an annoying fault simple ... if not frustrating !!
Just a follow-up to this thread (a couple years on) haha. I have since purchased the requisite wiring loom and sensors to (re)install parking sensors in the XJR-100. However, I am unsure where to drill the holes in the bumper to mount them.
Is there any chance that I could trouble someone to measure the exact locations of the rear parking sensors in the bumper, so that I know where to mark and drill? I would really appreciate if any of you fine gents have the time! Looking forward to hearing back.
I'll do my best, some crude pics, but the center of the side sensors are 8" from the center of the side markers. In the picture it looks like the sensor is located lower than the centerline of the side marker, but it is a bit of an illusion, by eyeballing them they are pretty much along the same horizontal centerline.
The rear sensors, find the middle of the rear bumper and place the two rear sensors 20 1/2" apart center-to-center. They sit right on the slightly raised lower line of the bumper, if you measure down from the top of the bumper to the center of the sensors it is 6 1/8"
I'll do my best, some crude pics, but the center of the side sensors are 8" from the center of the side markers. In the picture it looks like the sensor is located lower than the centerline of the side marker, but it is a bit of an illusion, by eyeballing them they are pretty much along the same horizontal centerline.
The rear sensors, find the middle of the rear bumper and place the two rear sensors 20 1/2" apart center-to-center. They sit right on the slightly raised lower line of the bumper, if you measure down from the top of the bumper to the center of the sensors it is 6 1/8"
Hope this helps
Thanks mate! This was exactly what I was looking for and help get me started. Going to be one of those "measure 8 times, cut once" endeavours. I really appreciate you taking the time to help me out with that! If anyone has any further suggestions/information on this one, please don't hesitate to share!
09-20-2014, 03:17 PM
