Key fob not unlocking/locking doors

[SteveC]

I have a 2001 Passat V6 TDI and overnight both key fobs started to fail to lock/unlock the car doors. Occasionally, one or other fob will unlock or lock but 95% time they fail to work and I have to resort to using the key.

Both batteries have been changed and this made no difference.

In desperation I took it to a dealer for a quick look who indicated that they thought it might be the control unit but would require 2 hours (approx £140) to check it out and to confirm if it was the control unit and if so a replacement would cost a further few hundred.

Can anybody suggest any other options or than get rid of the car!

[passat 130 tdi]

try taking the main battery earth off for a while - reconnect , this reboots the ecu and it will then learn the remote codes once more- worked for me and a few others on here.,

[Hex69]

Check your plenum chamber like this

https://www.vwaudiforum.co.uk/forum/s...ght=water+leak

[SteveC]

Thanks for the suggestions:-

Tried disconnecting the battery for a minute or so (is this enough) but problem remains.

With regard to the plenum chamber; VW did a recall on this some time ago.

I've had the battery out and the drain holes appear clear.

Anybody have any other suggestions?

Steve

[Hex69]

Thanks for the suggestions:-

Tried disconnecting the battery for a minute or so (is this enough) but problem remains.

With regard to the plenum chamber; VW did a recall on this some time ago.

I've had the battery out and the drain holes appear clear.

Anybody have any other suggestions?

Steve

You say they appear clear?

Have you tried pouring some water down and seeing if you get 2 puddles under the car.

Check the carpet on the passenger side (front and back) for wetness. If so, you will need the check the CCM module under the passenger seat for water ingress and/or corrosion.

Also, another common failure is the wiring in the door, which can cause issues.

[SteveC]

No I did not do a pour test - does this mean I have to strip the thing down again?

The carpets on the passenger side (front and rear) are bone dry and have never been wet (to my knowledge).

How do you access the CCM? I crawled around and found a cable that appears to run towards the centre of the car and disappears under the carpet, but can't locate the unit itself.

Steve

[SteveC]

Further to the above: -

I found the CCM. Both the carpet and underneath it are bone dry. Removed the box containing the CCM and this is also dry. Removed the CCM PCB and this appears okay and no sign of water ingress. Disconnected the 2 leads and only thing I could find was that one of the pins and its equivalent socket appear green. Cleaned up the contacts but this made no difference.

The harness also appears fine and there does not appear to be any breaks (although not tested with a fluke).

Where to from here?

Steve

[Hex69]

Further to the above: -

I found the CCM. Both the carpet and underneath it are bone dry. Removed the box containing the CCM and this is also dry. Removed the CCM PCB and this appears okay and no sign of water ingress. Disconnected the 2 leads and only thing I could find was that one of the pins and its equivalent socket appear green. Cleaned up the contacts but this made no difference.

The harness also appears fine and there does not appear to be any breaks (although not tested with a fluke).

Where to from here?

Steve

Hmmm, you've exhausted my ideas.

Ah, just one more thing to try.

Have your remotes lost synchronisation?

If they have you can resynchronise, it tells you how to do it in the handbook.

[Hex69]

No I did not do a pour test - does this mean I have to strip the thing down again?

Just try pouring some water down the side, under the cover and see what comes out.

[SteveC]

Tried the pour test and yes it comes out without problem and both keys are synchronised.

However, whilst messing with the harness the remotes started working again! Put all back together and replaced trim and confirmed stil working. Sat in passenger seat and they stopped working - disturbed the harness perhaps with feet?

Anyway, stripped down again and moved harness about and all started working once more.

Suspect harness at fault but nothing obvious. Also not sure which pin the remotes use.

Put all back together once more, seating the module better and all working for now- thank god


Thanks for all your help
Steve