B4 Avant central locking, leaks

Posted: Mon Jul 20, 2015 11:22 am

I have a serious amount of water (fresh not washer water) ingress on my central locking pump causing some electrical mayhem (indicator lights permanently on, alarm horn randomly buzzing and humming of the unit).

To get me home I disconnected the unit - 3 connectors. But I realised I had to reconnect the unit to release the filler door.

Questions:
1. I am looking for tips for where the water may be coming from. Info. There was a monumental amount of rain and the car was parked up a steep incline (nose upwards). This may have been happening over time though (I regularly park on hills). I was thinking through the seal right rear light. Possibly it was condensation? the foam surrounding the pump was drenched too.

2. Can I disconnect the unit? As in, disconnecting the vacuum connector. I am worried I loose system vacuum needed to operate the central locking. Or is it a simple plug in plug out system.

3. I popped open the case of the unit - plenty of corrosion. I will clean it up but I prefer to remove the unit and study the PCBs under a microscope. If it is a common problem are there specific areas I need to look at.

4. My part number is 4A0 862 257 J (Hella) - are these the same as in saloon B4s? I can get hold of these pretty easily.

Thanks

Needs to get out more Joined: Feb 07, 2011 Posts: 114

I thing your leak may be coming from blocked rear sunroof drains. You can clear this by either blowing compressed air through the drain holes or fishing a length of weed trimmer line trough them. Can't help with the CL pump as I've had an issue with mine for years and have not had the time to trace it.

Posted: Wed Jul 22, 2015 7:40 pm

That makes a bit of sense - I've had a very intermittent sunroof (only twice) leak too. The front drains are clear but I've not located the rear drains yet. No idea where either the entry or exit holes are.

CL pump has been a success. I unplugged the electrical connectors, not the vac connector. Then I popped off the cover. Load of corrosion, air dried, sprayed with isopropyl alcohol and brushed and wiped the PCB. The plastic case had corrosion residue too, cleaned. Reassembled and all good. Amazing the abuse some of these parts can take!

Needs to get out more Joined: Feb 07, 2011 Posts: 114

On my UrS6 and B3 Coupe the drains can be seen by tilting the sunroof and looking in the corners towards the rear

Posted: Sat Jul 25, 2015 8:01 pm

Awesome, I was try to find them with it slid open. That makes more sense. I'll take a look tomorrow. Cheers