Rear parking sensors not working, thinks the caravan is still attached

Audio, Navigation, Electronic Faults and Fixes
Post Reply
RonA
Posts: 5
Joined: Wed Jan 18, 2017 11:17 am

Rear parking sensors not working, thinks the caravan is still attached

Post by RonA » Tue Jun 12, 2018 1:38 pm

My 66 Disco sport has just developed a curious fault.
The vehicle is fitted with a tow bar & I have towed my caravan several times without incident, electrics working beautifully.
On return from a run at the weekend the rear sensors are not working with a message on the display screen saying they will not work with a trailer connected. However this alarm has persisted despite the caravan being removed. Front sensors are working perfectly.
Anybody had this problem & any thoughts on how to clear the alarm.
Thanks in anticipation
RonA


User avatar
BFGDSMan
Posts: 648
Joined: Thu Mar 19, 2015 5:10 pm
Location: North Germany and sometimes South Germany

Re: Rear parking sensors not working, thinks the caravan is still attached

Post by BFGDSMan » Tue Jun 12, 2018 2:03 pm

I reckon you have the following options:

Is it a factory fitted towbar? - if yes then back to dealer

Is it aftermarket with dedicated electrics kit? - just lift up the boot floor and take out the tool tray and you will see a large rectangular multi-pin plug connected to the left of the boot floor - tricky. The kit is plug and play without further coding required to make it work. I would suspect either a software re-boot or similar needed or a poor (earth?) connection allowing to the reversing pin in the plug (pin 8 on a 13 pin plug I think off the top of my head).

Here are the fitting instructions for the 13 pin kit : https://www.kupplung.de/out/media/13125 ... les-v1.pdf (pictures 7, 8 and 9) so you can see the connector I mean. Don't reckon you would get much joy out of JLR with this (unless one of their dealers fitted it).

Is it aftermarket and a general electrics kit with after-market smart relays? - If you have the receipt of where it was fitted then take it back to them as clearly the smart relay is not doing its job. My personal opinion is that such kits are a false economy with modern CAN BUS wiring systems, especially for the DS when the kit above retails at €31.00 + postage?

Does this help? Let us know how you get on.
Gone: SD4 HSE, TD4 HSE Lux.

Going: TD4 HSE Lux Auto (before it falls apart)

Arriving Mid Sep - Mercedes E220d AMG Cabriolet
Arriving Mid Oct - Mercedes E220d AMG Estate


RonA
Posts: 5
Joined: Wed Jan 18, 2017 11:17 am

Re: Rear parking sensors not working, thinks the caravan is still attached

Post by RonA » Tue Jun 12, 2018 2:33 pm

Thanks for that, the tow bar & electrics (compatible with both standard filament & LED lighting) are both aftermarket. I know exactly where the box you refer to is, as I fitted the towbar & electrics myself. Will try what you suggest Ill let you know how I get on.
RonA


RonA
Posts: 5
Joined: Wed Jan 18, 2017 11:17 am

Re: Rear parking sensors not working, thinks the caravan is still attached

Post by RonA » Tue Jun 12, 2018 4:40 pm

I disconnected the towbar electrics at the connection you mentioned & the fault cleared. All working as it should be.
However after reconnecting the plug the fault came back. Earth connections confirmed all good & tightt.
Decided to leave towbar electrics off for time being, simple enough to reconnect if I need to do some more towing.
Any idea how you carry out a software reboot?
RonA


MikeJohn
Posts: 47
Joined: Fri Oct 20, 2017 10:00 pm

Re: Rear parking sensors not working, thinks the caravan is still attached

Post by MikeJohn » Tue Jun 12, 2018 5:29 pm

This sounds like a fault on the lead that's being plugged in. The simpler ones (ie cheaper!) have no electronics at all but do not work with LED trailer lights.

The "better" ones work with LED or filament lamps and have some electronics in lead that the car sees as a higher wattage load, and thus the car knows a trailer is attached.

That electronics should NOT be indicating the higher load to the car if the trailer is not actually plugged in, so it sounds pretty certain the adaptor lead has failed somewhere.

Simple to replace, and if recently fitted probably could be returned under warranty.

You may even be able to identify and fix the fault if you have some electronics knowledge, I have not seen inside one but they should be fairly simple.

Mike
MY17 DS HSE 180 Auto InControl Pro, Space saver wheel. Tow Trust detachable towbar.


User avatar
BFGDSMan
Posts: 648
Joined: Thu Mar 19, 2015 5:10 pm
Location: North Germany and sometimes South Germany

Re: Rear parking sensors not working, thinks the caravan is still attached

Post by BFGDSMan » Wed Jun 13, 2018 7:54 am

RonA wrote:
Tue Jun 12, 2018 4:40 pm
I disconnected the towbar electrics at the connection you mentioned & the fault cleared. All working as it should be.
However after reconnecting the plug the fault came back. Earth connections confirmed all good & tightt.
Decided to leave towbar electrics off for time being, simple enough to reconnect if I need to do some more towing.
Any idea how you carry out a software reboot?
RonA
RonA,

Happy days that we now know where the fault is (even if we don't know what it is!). So we must assume that the park sensors/wiring/software is working correctly as it works perfectly when you disconnect the towing wiring. Does your caravan have LED lights - if it does then this may not be causing enough resistance in the circuit so the car won't think that there is a trailer attached?

Not 100% clear from what you wrote but I shall assume you have the plug and play dedicated wiring kit. Two options (?)

  • Phone/contact the company where you got the kit and ask if they have had anyone else with the same fault (could be a faulty batch)
  • On my kit I had to connect the wires into the 13 pin plug as they give you a choice of rubber bungs depending on whether you are fitting a fixed or removable towbar. Could be worth checking if you have the same sort of kit as me (mine is the one referenced in the hyper-link in my original reply to your question) that there isn't a stray wire in the actual 13 pin socket?
The only other thing I can think of is a). making sure the three earth wires (pins 3, 9 and 13 if I remember) are correctly contacting the car body metal in the boot or b). having removed the multi block connector you put a circuit tester (or flyer cable) between the reverse and the earth contacts and see if this replicates the fault - if it does then to me this would indicate a fault before the multi pin block on the car side and not the tow bar side??

:?: :?: :idea: :idea:

BFG
Gone: SD4 HSE, TD4 HSE Lux.

Going: TD4 HSE Lux Auto (before it falls apart)

Arriving Mid Sep - Mercedes E220d AMG Cabriolet
Arriving Mid Oct - Mercedes E220d AMG Estate


Post Reply

Return to “Electronics and In Car Entertainment”