Accessing BCM

[Tander]

To get the BCM out? Fck no.

To trace the water ingress? Maybe but highly unlikely.

Find a local VW Group specialist.

So another update. Coolant migration. This is the term used.

Local garage has been great and diagnose the issue and repair steps. Price is less than 1/2 what the dealership quoted.

This is their report:

“confirmed customer complaint. removed body control module and confirmed there was water ingress to control module, one pin has broken off and there are signs of corrosion. BCM will require replacement and wires in plug will require repair. traced water leak to coolant expansion tank. this is a known issue and coolant leaks through plug, down loom and into BCM.

replacement of BCM and expansion tank required. will need to soak loom in isopropyl alcohol to get coolant out.”

 

[Craig.]

Yip, seen water track along a loom a few times, not coolant specifically but it absolutely can happen.

One of my favourite ones was water tracking along a throttle pedal loom (not from the pedal obviously) into the ECU of a Transporter.

 

[Tander]

Yip, seen water track along a loom a few times, not coolant specifically but it absolutely can happen.

One of my favourite ones was water tracking along a throttle pedal loom (not from the pedal obviously) into the ECU of a Transporter.

This is called coolant migration apparently. Not super common but known issue.

Car is now all sorted. Except the Cruise control doesn’t work (it did before) and the door card lights don’t come on. No errors on the dash. Will plug in the OBDeleven later.

 

[SuperV8]

This is called coolant migration apparently. Not super common but known issue.

Car is now all sorted. Except the Cruise control doesn’t work (it did before) and the door card lights don’t come on. No errors on the dash. Will plug in the OBDeleven later.

Glad its sorted.

“ traced water leak to coolant expansion tank. this is a known issue and coolant leaks through plug, down loom and into BCM.

Do you know which plug/loom the water tracks through?
Is it the coolant level plug/loom?
Seems like a worthwhile preventative check!

 

[East Yorkshire Retrofits]

This is called coolant migration apparently. Not super common but known issue.

Car is now all sorted. Except the Cruise control doesn’t work (it did before) and the door card lights don’t come on. No errors on the dash. Will plug in the OBDeleven later.

Possibly installed the wrong BCM, or not configured it properly . That or they’ve put the wiring back in the wrong position after re crimping (depending on what they’ve reterminated)

What’s the cruise control doing/not doing? Post the error codes once you’ve read them, along with the identification data from the BCM

 

[Tander]

Possibly installed the wrong BCM, or not configured it properly . That or they’ve put the wiring back in the wrong position after re crimping (depending on what they’ve reterminated)

What’s the cruise control doing/not doing? Post the error codes once you’ve read them, along with the identification data from the BCM

Thanks for the detailed post.

Wife just got back home so I had a chance to scan and check.

CC was switched off on the stalk.
And the door card lights were turned off in settings for some reason.

Scanned the car. Zero errors.

I do wish the car had ACC though. But it’s a manual so retrofitting isn’t possible I believe.

 

[Tander]

Glad its sorted.



Do you know which plug/loom the water tracks through?
Is it the coolant level plug/loom?
Seems like a worthwhile preventative check!

I think the coolant level plug. The preventative maintenance is literally to drill a weeping hole by the plug so it goes out there next time bottle fails and not into loom. Seems so silly.

 

[East Yorkshire Retrofits]

Thanks for the detailed post.

Wife just got back home so I had a chance to scan and check.

CC was switched off on the stalk.
And the door card lights were turned off in settings for some reason.

Scanned the car. Zero errors.

I do wish the car had ACC though. But it’s a manual so retrofitting isn’t possible I believe.

Perfect, nice easy fixes

 

[grabania]

I do wish the car had ACC though. But it’s a manual so retrofitting isn’t possible I believe.

I did retrofit ACC in my Leon MK3 with manual and it works perfectly fine

 

[East Yorkshire Retrofits]

Thanks for the detailed post.

Wife just got back home so I had a chance to scan and check.

CC was switched off on the stalk.
And the door card lights were turned off in settings for some reason.

Scanned the car. Zero errors.

I do wish the car had ACC though. But it’s a manual so retrofitting isn’t possible I believe.

Manuals can have ACC

We can do this for you