Electric sliding door control failure

Longer · Jul 16, 2020

Hi Guys,

So two days before a planned trip the sliding door has failed!

The door doesn't respond to the exterior door handle or the internal handle, the latching/locking servo doesn't run either. UNLESS - the engine is running then the system works well as normal, locking servo, audible alarms, normal motor noise etc.

I've checked the fuse under the left hand seat which I believe is the sliding door control supply and it's good.

Any ideas, gratefully received. Cheers;

mickmull · Jul 16, 2020

Sounds like the battery supplying the sliding door mechanism doesn't have enough charge to operate the door. When the engine is running there will be enough supply to operate the mechanism. Not sure where the door is powered from - but there's a chance that if the main battery doesn't have enough charge then services like the electric door and wing mirrors may not operate to preserve starting ability. So perhaps a good run and a charge is needed or a new battery.

The other thing may be a worn or frayed cable that has a higher resistance to carrying the supply - which is then overcome when the engine is running. Good luck and have a great holiday!

Alan Andrews · Jul 16, 2020

Yes the engine battery is low power.

The same happens with the rear tailgate if the battery is low power.

kurienp · Jul 16, 2020

Longer said:
Hi Guys,

So two days before a planned trip the sliding door has failed!

The door doesn't respond to the exterior door handle or the internal handle, the latching/locking servo doesn't run either. UNLESS - the engine is running then the system works well as normal, locking servo, audible alarms, normal motor noise etc.

I've checked the fuse under the left hand seat which I believe is the sliding door control supply and it's good.

Any ideas, gratefully received. Cheers;

Longer, this may just point to a weak starter battery ... on its way out. Good it happened before your journey. A good shop should be able to test and replace the battery for you quick and easy.

Enjoy the journey.

Ch1pbutty · Jul 16, 2020

kurienp said:
Longer, this may just point to a weak starter battery ... on its way out. Good it happened before your journey. A good shop should be able to test and replace the battery for you quick and easy.

Enjoy the journey.

If you need a new battery, can recommend AA/RAC + mobile fitting. They will only replace if it needs replacing, but will also check for other faults if you speak to them nicely.

Longer · Jul 18, 2020

mickmull said:
Sounds like the battery supplying the sliding door mechanism doesn't have enough charge to operate the door. When the engine is running there will be enough supply to operate the mechanism. Not sure where the door is powered from - but there's a chance that if the main battery doesn't have enough charge then services like the electric door and wing mirrors may not operate to preserve starting ability. So perhaps a good run and a charge is needed or a new battery.

The other thing may be a worn or frayed cable that has a higher resistance to carrying the supply - which is then overcome when the engine is running. Good luck and have a great holiday!

Thanks for taking the time to reply. From what I can imagine about the system it makes sense that when the engine is running the alterator would give a supply, and then I imagine (maybe someone could clarify this) when the motor stops a switching relay swaps ,over the supply. All the voltages are fine, the leisure batteries are solar charged so topped up. And the fridge and other leisure consumers are fine.

mickmull · Jul 18, 2020

I think the electric door is run off the main starter battery. Makes sense as this feature is available on other VW vans. So I think it will be your starter battery that has been a bit low. If the symptoms are still there after a long drive or if you have charged the starter battery separately then for peace of mind I would change that battery. Don’t want a holiday spoiled by the bus not starting! Happy hols.

Longer · Jul 19, 2020

@mickmull cheers for the reply. The battery is only a couple of months old and just to be sure I load tested it. There's definitely a change over relay that has lost power or something along those lines. The door works with the engine running and I'm now in Annecy with cold beer; so it can wait until I get back. Thanks again.

mickmull · Jul 19, 2020

Longer said:
@mickmull cheers for the reply. The battery is only a couple of months old and just to be sure I load tested it. There's definitely a change over relay that has lost power or something along those lines. The door works with the engine running and I'm now in Annecy with cold beer; so it can wait until I get back. Thanks again.

Annecy - Tre Jolie! Yes could be a relay - but you don't want to be studying wiring diagrams while drinking beer... have a 'bon vacance'