MK6 Central Locking - Cargo doors lock but front doors don't

[Symon]

Hi all,

I've searched this issue and can't find anyone with similar symptoms.

My issue is the central locking doesn't lock the front doors. If I quickly double press the lock...the back and side doors lock but the fronts just bounce from locked back to unlocked.

This all started when the back doors swung open on a job. And although there are some unconnected cables (in the driver's side back door) I presume these are just from a standard loom and for things like rear window heaters etc (which aren't needed on a LWB Hi-top). Everything else looks fine and it is likely a coincidence.

Can anyone help me track down the issue, please? Hopefully the described symptoms are a good start.

Many thanks.

[Symon]

All fuses seem fine

Not sure what's next on the check list.

[TriumphStag]

Have you checked the two taped to the bottom of the steering column? These are the ones that do the central locking.

[Symon]

Hi,

Thanks for your help.

I could only find one and it's fine (15amp).

It's weird that the back locks but the front bounces.

[TriumphStag]

There should be two there on a MK6. One fuse is for the front, one for the back. Have another look
They should be taped up onto the column.

[Symon]

Yep, found it Further towards the firewall.

Fine also

Thing is, if I remove the one near the steering column...it kills everything. If I remove the one further away...it changes nothing. Same issue. But it's got continuity.

[Symon]

I'll check the wiring after the good fuse that does nothing. Could be something from there to the CL control unit. The both share a live from the same source(according to the diagrams).

Looking at the wiring diagrams...it could be a long search.

[Symon]

Just found the door open switch is completely broken.

I thought this was just interior lights as the CL wiring diagram doesn't mention them. However, the door lock assemblies show pin 8 as "ajar".

So I've checked the interior light diagram and this shows this is connected to the CL control unit!!! Thank for not including that in the central locking diagrams...Mr Haynes!

I will report back if this fixes the issue

[Symon]

No joy yet.

In the process of taking off the door cards to check voltage at the pin 8s on the door lock assemblies (black and blue). So far driver's door shows no voltage at pin 8 on locking. I presume it should as it sends to the CL control unit. Earthing them at the door will not bypass them if the wire is broken upstream. I'd have to do that at the CL control unit. Think it's behind the glove box in a bitch of a place

I'll check the passenger door now.

[ake]

I think your lock control module is dead.

[Symon]

If it was dead would it still lock the rears? Don't think it's dead...yet

I've started on the rear driver's side door and it's a mess. Lots of unconnected connections that I presume are for unused things like rear wiper, heated window etc.

BUT, I've released the loom and the bit where it's a taped cross over has a bunch of black wires cut!!!!! Near on impossible to identify which goes where as they're all black.

But the back doors still locked

I'll post a pic shortly.

[Symon]

Here's a couple of pics. I'll remove the rest of the tape once I've secured the few that are hanging by a thread! At least there will be less to identify

Weird thing is...the back doors locked! Presumably the few remaining connected are the power ones.

The one that goes right is to the black plug in the second pic. Likely unused rear wiper or similar.

The one that goes down is to the two female spades in the second pic. I presume these are for unused rear window heater.

The one that goes up, then to the right, is for the door lock.

All black...so this will be fun

[paul2012]

Here's a couple of pics. I'll remove the rest of the tape once I've secured the few that are hanging by a thread! At least there will be less to identify

Weird thing is...the back doors locked! Presumably the few remaining connected are the power ones.

The one that goes right is to the black plug in the second pic. Likely unused rear wiper or similar.

The one that goes down is to the two female spades in the second pic. I presume these are for unused rear window heater.

The one that goes up, then to the right, is for the door lock.

All black...so this will be fun

Fit a replacement rear door loom They're easy to get hold of

[Symon]

Yeh, was going to go to a scrappy tomorrow.

However, after removing the loom, which disconnects behind the rear light, I can play a game of matching the pins to the colours (on the van side of the connectors) and use a continuity test on the blacks to see what should go where. Great fun for a Sunday night! Ha!

But yeh, tomorrow I'll see if heading to a scrappy is needed

Seems only sheer luck allowed the rear doors to continue working but they were sending the incorrect door ajar signal. Cuts aren't in the hinge loom, either. They're cut from that sharp support in the middle of the door

I'll report back once this thing is cleaned up/replaced.

[Symon]

So I spent a few hours working out which black wires went to which colour ones. But it was late and I realised I didn't have enough small heat shrink to sort it all out. So I headed home.

On my way back here I swung by my transit reliable scrappy. £5 for the rear loom! Cheaper than buying the heat shrink. No brainer.

I now have a fully working central locking system

Thanks very much to all who chipped in and have a Merry Christmas

ps. The second 15 amp fuse under the steering column (nearest the firewall) has no effect. Looking at the wiring diagram it's possible it's a backup fuse. Whether it's in or out makes no difference to the CL. So I think it's a back up.