Both me and a buddy of mine recently bought L322 Range Rovers, and both of the had faulty parking sensor systems! – here is some info on troubleshooting the system:-
The parking sensor system on the L322 consists of 8 individual sensors and a central control unit, if there is a problem with any one of the sensors the whole system stops working. The most likely failure modes are a failed sensor or damaged wiring to a sensor, the control units seem to be fairly robust with few reported failures.
The sensors are ultrasonic – they send out a series of high pitched clicks and listen back for a echo – the same way bats navigate in the dark and locate food while they are flying.
An easy way to check if the sensors are operating is to activate the system using the button on the dash (or put the vehicle in reverse, make sure you don’t run over yourself) and put an ear to each sensor in turn. When there is a problem you will probably have a flashing light on the button and no proximity warning tones but the system will still try and operate the sensors – you will be able to hear a faint clicking sound from any sensors that are working correctly.
If you find one that isn’t clicking try swapping it out for a sensor that is working, if the problem moves with the sensor you know it the sensor itself that is the problem and it’s just a case of swapping it out for a new sensor (cheap compatible sensors are available from eBay, Amazon etc and in my experience at least they work as well as expensive Land Rover original sensors).
The sensors themselves just clip into place and by reaching round to the back of the sensor you can release the clips and pop them out of the back of the bumper.
This proved to be the problem on my Range Rover, but on my buddy’s Range Rover the fault didn’t move with the sensor, indicating that is was more likely a wiring problem.
We removed the rear bumper to get access to the wiring, and using a multimeter checked for continuity from each sensor pin to the multiplug connector where the bumper connects to the car. We found one wire where moving/bending the wire caused an intermittent connection, and on inspection water found a split in the insulation that had allowed water to get in and corrode the copper wire inside.
Cutting out the offending section of wire and soldering in a new length of wire with heatshrink over the solder joints soon fixed the problem and got the whole system operating correctly again.
Hopefully this information was useful to you, if you have any comments or questions, let me know below.
Here is an example of a cheap parking sensor on Amazon (I have no connection with the seller – check parts numbers to make sure it is right if you decide to buy!)
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