ParkPilot thinks a trailer is attached after battery drain...

[Captain_Bacon]

Hi all, long time lurker, and I thank you all for the information I've found on here, but this seems to be a new one...

I have a 3 and a smidge year old T32 Kombi. It had the parking sensors and detachable tow bar.
In the last couple of weeks it's had alternator issues which resulted in being towed to the dealership with a flat battery (I was on my way there anyway...died en route). New alternator (£700+vat!). Battery now charging.

Unfortunately the battery drain has led to some interesting side effects. Perhaps related, perhaps not. The reversing sensors no longer work as it thinks that there is a trailer attached (shows up with a trailer in the reversing UI on the dash), and also my indicators are blinking double-time on the dash like there's a bulb gone. BUT, they're flashing at normal speed on the outside. There's also a bulb failure light on the dash, and the rear fog light isn't working, even though the dealer changed the bulb. It all seems to be connected in my mind.

I entirely don't trust the dealer (they're talking about shorts in the wiring loom, might need to be replaced etc...).

I'm looking for some help before a start crying and rocking in a corner!

Thanks in advance all!

 

[Pauly]

All the things you are describing are standard towbar connected actions ie rear sensors disabled, foglight moved to trailer etc even the double speed flash is correct of you have a trailer connected and it has a lamp out

Flat battery/low voltages can play all kinds of havoc, if i was you my first step would be to fully charge the battery and disconnect it from the vehicle for a bit to let everything reset
If the fault persists then you are going to need to get the vehicle scanned and depending on whats found any fault codes reset
If the fault still persists then i would (maybe just temporarily to fault find) either code out the trailer module or simply unplug it and see if the fault clears

 

[Pauly]

Where abouts are you ?

Ideally you want VCDS software and lead to do some digging but if no one is close to you then carista may be a cheap option for you to check and clear any fault codes ?

 

[Captain_Bacon]

Thanks Pauly!

That diagnosis was where my head was at too, but it's just guesswork for me - you're the pro!

I'm based in Oxford at the Weekends and N. Somerset Mon-Fri (Thanks Covid!).

I'm going to head up to Bristol for a nice drive (hour or so round trip) to get some juice in to the battery, then take the battery clamps off tonight, see if that helps. In other threads during my search I noticed that there was a suggestion that 'shorting' the circuit (i.e. no battery, just putting the +ve/-ve terminal clamps together) might help with capacative discharge - what do you think?

I've goot an OBDII dongle (just a cheap one) installed in the van at all times (don't get me STARTED on the blooming EGR/DPF issues I've had!), but I don't know about VCDS or Carista. I use Torque pro and some other random car scanner.

Thanks again!

 

[Captain_Bacon]

Just thinking, that I'd be quite happy to remove the trailer module, as I've never actually used it. Could always replace it if necessary, or as/when I can afford to deal with it. Don't suppose there are any workshop manuals that you know about saying how to do so? I've not really got my hands dirty yet (lease vehicle, main dealer mandatory servicing), so I have absolutely know idea where stuff is really. Plus the ADHD .

 

[Big Al]

Have you tried to check your trailer socket for water/corrosion?

 

[Pauly]

I'm going to head up to Bristol for a nice drive (hour or so round trip) to get some juice in to the battery, then take the battery clamps off tonight, see if that helps. In other threads during my search I noticed that there was a suggestion that 'shorting' the circuit (i.e. no battery, just putting the +ve/-ve terminal clamps together) might help with capacative discharge - what do you think?

Wont do any harm, shorting the leads just discharges any residual energy quicker but leaving them off for a while does the same job

I've got an OBDII dongle (just a cheap one) installed in the van at all times (don't get me STARTED on the blooming EGR/DPF issues I've had!), but I don't know about VCDS or Carista. I use Torque pro and some other random car scanner.

Any tool will do, there are all similar and any ODBII should be capable of reading and resetting

 

[Captain_Bacon]

Have you tried to check your trailer socket for water/corrosion?

Not yet, but I'm pretty sure it's not that as I watched the problem happen in real time as the Christmas tree effect happened while on the side of the M5 waiting for recovery. Worth a look later though just in case.

 

[Littleblackflash]

Socket was my 1st thought. Inside the socket is a small micro switch tab which detects the trailer is attached. Unfortunately they are not well sealed against water and this is likely to be your problem. Spray some WD40 in there to be sure.

 

[rover220]

Socket was my 1st thought. Inside the socket is a small micro switch tab which detects the trailer is attached. Unfortunately they are not well sealed against water and this is likely to be your problem. Spray some WD40 in there to be sure.

That switch isn't for trailer detection, that takes care of the fog light switching iirc. The van knows the trailer is attached by monitoring the lighting circuit

 

[Captain_Bacon]

So I disconnected the battery overnight, decided not to short it in the end. Came out, reconnected and.... nothing. No change.

Pants.

Thoughts?

 

[Deaky]

So I disconnected the battery overnight, decided not to short it in the end. Came out, reconnected and.... nothing. No change.

Pants.

Thoughts?

Take the towing socket apart. If the fog light has switched, this is only done mechanically by the switch in the socket. Check for corrosion. It's probably full of salty water.

 

[Captain_Bacon]

I'll have a look in a bit. Ta.

I've just noticed that my windows don't do the 'one press' up and down anymore either.

Connected?

 

[Deaky]

I'll have a look in a bit. Ta.

I've just noticed that my windows don't do the 'one press' up and down anymore either.

Connected?

If you've disconnected your battery you will need to reset one touch closing

 

[Captain_Bacon]

If you've disconnected your battery you will need to reset one touch closing

Oooh, ta! Um, sorry for beingthe idiot there. Just reset them now. Thanks!

 

[Captain_Bacon]

This is a photo of the trailer electrics. Pretty good looking from what I can see? Anyone tell me what to be looking at/for?

 

[Deaky]

This is a photo of the trailer electrics. Pretty good looking from what I can see? Anyone tell me what to be looking at/for?View attachment 100617

You need to unscrew it an look where the wires go in the back

 

[Littleblackflash]

The pin in the circle is the switch to detect the plug is connected. But as Deaky says, undo the screws and clean it out from the inside.

 

[Captain_Bacon]

How am I looking? To the uninformed it looks, well, good...

 

[Captain_Bacon]

View attachment 100618

The pin in the circle is the switch to detect the plug is connected. But as Deaky says, undo the screws and clean it out from the inside.

Am I REALLY that much of a potato, but, well, I don't think there's a switch in there...