Parking sensor issue

[Hessles]

Ever since we bought our Caravelle the parking sensors haven’t worked. I’ve had a look with VCDS and all 8 sensors show as an infinite distance and don’t change during logs. To me this points to a common point of failure.

Is there any further tests I can do with VCDS to narrow this down? Could it be the 8K unit at fault or more likely a common issue with the 12v or earth.

Any useful tips to check wiring with a multi meter?

TIA

 

[Pauly]

If you can see the distance measurements then I guess it’s safe to assume the PDC module is powered and connecting so the power supply and canbus are ok

Is the module not reporting any errors ?
What does the VCDS scan look like ?

Each sensor has three wires connected to it
A common positive wire (maybe 5v ? I’m not 100% from memory)
A common negative wire
An individual sensor return wire

You could check a couple sensors to make sure that power is being delivered along the common feeds
If you put your ear to the sensors you can sometimes hear a faint audible clicking that lets you know they are functioning

 

[Anakin]

The only other thing I can add, in addition to @Pauly is to get one new sensor. You can then swap each one, one at a time and sometimes the whole system comes back as they are daisy chained together. (caveat, this works on my 5 series BMW, but it may be different in VW systems)

 

[Hessles]

Sorry for the potato quality screenshots.

 

[Pauly]

Ok so looks like you have lost the supply to the sensors
This could be as simple as water in a plug for one of the sensors or something worse like wiring etc

Rear bumper is probably easier to remove if it were me I would start there and unplug all the sensors and check for water/corrosion etc and see where you go

 

[Hessles]

Thanks Pauly. I’ll definitely start at the rear as I’ve just had the front end off and had all new sensors for the T6 facelift (parking sensors have never worked for me).

 

[Hessles]

Future reference for anyone having a similar issue. My PDC module was the issue. I removed the lower dash under the steering wheel to access the module which is screwed to the right hand side of the relay “cage”. The cage has to be unbolted (2x 10mm) from the metal framework and the relays unplugged and the holders pushed out of the cage.




Once I had access to the module I removed the plug to the rear sensors and had a look with VCDS. This still showed 0.5v to the sensors (should be 5v output). I removed the plug for the front sensors and nothing changed.

Upon removing the module I was faced with this.



Now I need to track down another module.

 

[Hessles]

@Pauly do you know if a second hand module with a later suffix would work? I can code it to suit the F&R sensors and trailer. Is it VIN locked?

The module I’ve found has T at the end and mine is J (T5.1).

 

[Pauly]

Not VIN locked or anything but not sure about part number suffix ?
It may well work if you copy over the original coding but I’m not 100% either way, if it’s cheap may be worth a try
Just make sure it says Parkhilfe 8K same as your old one or it defo won’t work

 

[mmi]

Ever since we bought our Caravelle the parking sensors haven’t worked.

Are you sure the 7E0 919 475 J is a correct one for the van.
As you haven't disclosed vehicle data it's difficult to tell.
For T5.1 (2012-15) would expect to have either of the following units onboard



EDIT:
Ok, "J" seems to be correct one as working the component installation chain backwards shows

 

[Hessles]

Thanks both! The T module I found was only 4K. I’ve found a module with the suffix AA which is 8K. This one should be fine.

I’ll pop into VW tomorrow and enquire on the cost of a new one and weigh it up against this one on eBay for £100.


This is mine for reference.

 

[Pauly]

AA is £290 + vat RRP from VW

 

[Hessles]

AA is £290 + vat RRP from VW

Thanks! I’ll go with the eBay item

 

[manfrotto]

Future reference for anyone having a similar issue. My PDC module was the issue. I removed the lower dash under the steering wheel to access the module which is screwed to the right hand side of the relay “cage”. The cage has to be unbolted (2x 10mm) from the metal framework and the relays unplugged and the holders pushed out of the cage.

View attachment 293344
View attachment 293345

Once I had access to the module I removed the plug to the rear sensors and had a look with VCDS. This still showed 0.5v to the sensors (should be 5v output). I removed the plug for the front sensors and nothing changed.

Upon removing the module I was faced with this.
View attachment 293342
View attachment 293343

Now I need to track down another module.

Good find @Hessles

 

[Hessles]

She’s alive, thanks for your help gents!