Took newly purchased 2006 LR3, 89k miles, to certified shop. Had diagnostic run then changed all fluids in running gear; rear locking diff, front diff, TC, and trans. I ask to be sure to check parking aid system as it was not functioning and that I could hear clicking (implying sensor working) only on three in rear and non in front. Mechanic said he never heard of this clicking thing and only one rear sensor (sensor not clicking btw) was showing fault. I was happily surprised. Bought non OEM sensor for a few bucks, installed it and it came alive clicking. The LR3 put in reverse beeped once and works fine beeping faster as obstacle distance is reduced..... At least the rear sensors worked fine and no flash amber light flashing as before indicating a fault. The front sensors do not respond. The front sensors make no clicking sound. Last, the sound from rear sensors speaker is weak and scratchy.
1. Any ideas how to diagnose and correct as the 'pro' scanner showed on rear one faulty?
2. Can the front sensors set to be inactive and would that show on the scanner? If inactive, is there an easy way to make active?
3. Could this be the front sensor speaker not working as I hear front sensors sound from different speaker?
4. Could this be the control module, but did not show on scan...?
5. Do the sensors click when functioning as I read and found true on mine? Does this mean a non clicking sound from a sensor mean that is the problem area or inactive?
6. Is there a good affordable scanner that can find faults, clear faults, check specific desired items, change options like making front front sensors active or inactive, and update firmware?

Not looking to be a LR mechanic but it can be a bit enjoyable and save some bucks still while still having the LR shop do the items real training and experience is needed.

 

I hear good things about the GAP, but have no personal experience. I seem to remember being able to disable front sensors, but nobody has ever asked me to do that, so I can't confirm or deny that as an option.
As far as all four not working, I'd be willing to bet there is a shorted sensor or a shorted wire behind the front bumper. All four sensors are wired in parellel and if there is a short, it pulls voltage down for all four sensors. The rear sensor was different, it just stopped working. That doesn't effect the other three.
To troubleshoot this, we usually scan for codes and if you have a code for all four sensors, then it is either disconnected (I think the main connector is under the driver side headlight, been awhile) or there is a short circuit.
If you confirm the bumper harness is indeed plugged in, then remove the bumper and unplug sensors one at a time until you hear the clicking. If the harness is shorted to bumper support like the fog lights usually are, they may start working as soon as you pull the bumper off.

 

To my understanding, if any sensor, front or rear has a fault, the entire system will not function. I spoke to the machinic today who run a complete diagnostic and confirmed only one rear had a fault. Mechanic also said if front was disabled, that should of shown on his scan and it did not. I have seen diagnostic scanners that the user would need to know all the menus and submenus as you are able to check specific items and change options. Son not know if there is a scanner that you press 'Check All', but it would seem so.

You could use a multi meter to check how much each sensor is receiving... maybe there is a slight reduction of power enough making the front not fuction but small enough not to send a fault..... I am falling down the rabbit hole.

Mechanic ask me to return so he can track it down.