Keeping my fingers crossed, my old Fabia BBZ is cooperating and so instead, I’ve a question about our Mk 4 GTi 1.8T that I bought brand new in 1998.  This forum has some real experts and so I could really do with some technical assistance as it concerns the dreaded VAG door locks.  
 

About five years ago, the VW OE door locks started to play up and after having a heart attack at the VW price, I bought a set of EBay specials at about £22.00 each. 
They fitted fine but very time consuming to get the job done.
My son bought the car off me a couple of years ago and everything carried on being OK. 
Then the replacement locks started playing up and so I replaced them again for him being a helpful Dad.
I did all four as I figured if two were playing up the rest will follow. 
 

Fast forward to about a month ago.

the drivers door will lock and audibly unlock but it would take repeated button presses and pulling on the handle to eventually release and open the door.
I know about the micro switches playing up so I bought another EBay special and after fitting it it was no better. I bought another lock from a different seller and much the same problem. 

So, with my son’s assistance, I stripped it down again today to ascertain what is happening as I held the lock outside the door with all the electrics connected and operated it using the remote, simulating closing the door with a screwdriver to operate the latch mechanism. 
 

It locks fine and you can see the lock actuator moving round to prevent the latch mechanism from unlocking, exactly as expected.
However, on unlocking, the lock does not rotate clockwise enough to allow the latch lever mechanism to operate fully. If I pull the lock round manually maybe another 0.5cm both the inner and outer door handles operate as expected and the latch opens as expected. I suppose repeated pressing on the remote must nudge it around enough for the latches to operate. 
 

So is there anything else on the car that would determine how much the lock motor rotates? Or is it just a coincidence that three EBay locks are all faulty in the same way?

I would hope that a brand new WV door lock would sort this out but I’m a bit concerned that three non originals have displayed the same fault and I would not my son to pay nearly £200 for no benefit.

 

Sorry that this has been a long post but I needed to give you all the information.
 

Thank you for  your assistance. 

 

56 minutes ago, prt57 said:

So is there anything else on the car that would determine how much the lock motor rotates?

Haven't fully digested that story, but I would suggest that the current supplied to the motor may be reduced if the relevant relay(s) in the central convenience module have 'tired' contact surfaces. Dirty/corroded contacts between connector pins on the way to the lock could have additional losses.

That reduced current might affect the behaviour of the motor and lock mechanism.

 

I'll have a better read of your info in the morning.

 

Changing out a few relays may be well worth doing before buying and trying any more locks.

Sorry it was a bit of a long story!!

 

I checked the wiring loom in the door jam and there were no breaks there. All of the connections within the door seem fine but it may be worth giving everything a spray with electrical contact cleaner. 
My son has found a 2nd hand genuine VW lock from what looks like a reliable breaker advertised as fully working. 
Its worth having another try at £25 and I can have a spray at the same time. 
there are no problems with any of the other 3 locks which hopefully removes faulty relays. 

After that I’m struggling a bit. 

I haven't delved into mk4 golf electrics, but on Polo 9N and Fabia there are separate relay coils/contact sets for each door, so I wouldn't rule out relays yet.

Will look at circuits and parts listings tomorrow.

 

What year is the car?  Sorry, dumb question, you said 1998 in the first post.

Edited 14 August, 20223 yr by Breezy_Pete

If the wire link from the outer handle to the inner lock assembly is incorrectly positioned it can give all sorts of problems 

43 minutes ago, nige8021 said:

If the wire link from the outer handle to the inner lock assembly is incorrectly positioned it can give all sorts of problems 

Yes, thanks for the reminder. Before I discovered the fault is with the lock motor not returning fully I had a play with having the cable tight and loose. I know if the cable is too tight the mechanism of the latch does not return to the home position and so it will not actuate the next time the handle is pulled. 

A quick look at wiring diagram says the Golf4 set-up is quite a bit different to what I'm used to, so the lock motor control is going to be local to the 'driver's door control unit'; presumably where any relevant relay is.  There is a central convenience control unit somewhere, but the door locks don't have any wires going directly to that, so presume that is mainly doing RF remote receiving and alarm related stuff.

Tempted to acquire a cheap ebay door control unit of this type for educational purposes. Does the car have electric fold-in mirrors?

 

 

Edited 15 August, 20223 yr by Breezy_Pete

Hi there,

thank you for researching this for us. 
No, we don’t have self folding mirrors. 

Pins 1* (blue/yellow wire) and 11* (lilac/yellow wire) of the 29-way connector at the door control unit are the ones going to the motor within the lock, I'd imagine from a dual changeover relay within the control unit. 

The microswitches that send mechanism position info from lock to module are wired to pins 5* and 28* of module, so confirming their integrity seems wise.

 

*ooh, hang on, pin numbers may be all wrong.  Seems to be a few variants.

 

Might be pins 6 and 13 at door module 23-way connector to motor in lock, same colours as above.

Pins 12 and 15 at door module receive the position inputs from lock,  these wires are grey/yellow and green/yellow respectively.

 

Apologies for messy info, one or other of those sets of pin numbers probably applies to your car, got myself confused.  If it's a 23-way connector at the door control  unit** it'll be the latter pin numbers, if 29-way, the first ones.

 

**no, to a control unit behind dash somewhere, see my next post below.

 

Edited 15 August, 20223 yr by Breezy_Pete
pin number variations

Thank you for your detailed information. 
When you refer to the door control unit,  are you referring to the large multi wired electrical connection that plugs into the window motor. This connection seems critical as with it unplugged all the electrics including the door lock are dead. As this is plugged in I can hear a slight click (relay) activating under the dashboard. 

On further scrutiny it seems I was being very hazy-sighted earlier.  

For the version with a 29-pin connector, yes door control unit is combined with window motor on the door.

 

If you don't have that version, the lock module connects to a 23-way connector on what is known as "Central locking and anti-theft alarm system control unit", located behind dash panel. The wires going via a 10-way connector at the A-pillar.

 

 

 

 

 

I’ll have a count up of the wires tomorrow, fingers crossed 29. 
Hopefully we have the unit connected to the window motor and then I can proceed with a bit of a clean out. 
 

Pete, your knowledge about this kind of things is phenomenal - amazing stuff!!

It was you I hoped would read my (long) post yesterday. 

Connector may not have wires in every positions, but there should be 29 possible wire placements. 

Not sure what the window motor looks like if you have the other version.

This is what I think is the lock control module  counting the connectors in the plug I can see 26. Difficult to see if any have more that wire leading to them at this stage. There are 3 unused blank spaces so that would make 29 in total. I’m going to give it a blast with electrical contact cleaner and I’ll report back  

Pinout diagrams:

 

Yes thank you, that is what it looks like. 
Mine is blanked at 9,12 and 13. 
All pins and sockets look fine with no apparent bent components. 
How do you think I should proceed?

Do you have a multimeter you could use to test continuity/resistance of the wires from that connector to the lock connector?

Will do you a little table of point to point pin numbers and wire colours a little later. It's going to be the first set of pin numbers I mentioned above, before doubts crept in.  Will add in the lock end connector info.

Yes, I have a multi meter. There should be 8 wires going to the front door plugs.

the rear doors from memory only have 6 wires.
I’m giving plenty of time for the contact cleaner to evaporate before reconnecting and having a trial run. 
Bearing in mind the components I have shown you, do you think it is likely that the fault is in the door rather than under the dash? I also exposed the wires in the door jam from the bellows and insulation. No apparent damage there. 
 

I may not to be able to go any further with this today due to work etc but I may have an opportunity tomorrow afternoon

13 minutes ago, prt57 said:

Bearing in mind the components I have shown you, do you think it is likely that the fault is in the door rather than under the dash?

Yes. 

Here's a little annotated image of the wires I think it would be great to check from 29-way connector to 8-way lock connector. The ones in the pink box possibly the most critical in terms of the lock mechanism telling the control electronics where it's at. Abbreviations from German colour names as follows ge = yellow, gr = grey, gn = green, li = lilac/purple, ws = white, br = brown, bl = blue

 

The earth wire from pin 7 at the lock goes to pin 29, shown on previous page of diagrams.

 

 

Thank you for the diagrams, most useful. 
 

just a little update as I have been to work and rewiring the fuel injector loom due to a little fire  ( Don’t ask!)

 

I thought the electrical cleaner had started to work as yesterday there seemed to be no problem with the lock operating as it should. Even this morning after leaving it locked over night it unlocked. 
However at maybe 18.30 after coming home from work tonight I tried unlocking and it was back to needing 3-4 presses on the remote and pulling on the handle.  
Why would it appear to be fine after only a short time but back to playing up when left for an extended period of time?

Hi Pete,

I thought that I would update you about the Golf Mk 4 door lock situation. 
I priced up a new genuine drivers door lock at my local VW garage at £231.00 but with a bit of discount it would have been about £200. 
So I searched for a preowned genuine lock and invested £33.00 in a known working example. 
It arrived yesterday and after fitting, all seems well so far. I am keeping my fingers crossed!
So it is fair to say that the quality of the Chinese rubbish on EBay that I had bought has sunk to a new low.  At least before this episode I’d get a couple of years out of them before they would play up. 
 

It is probably fair to say that a set of 4 locks from VW would probably send it to the scrapyard. 

A shame as we have fitted a full Milltek , a Forge TIP, a VR6 MAF housing with a Ramair filter and Saab 360cc injectors plus a K03s turbo so it is ready for mapping again at Mallory performance.

The fire damage I hinted at in my last post  is all fixed as I spliced in a loom for the injectors, throttle body and cam position sensor to the existing loom. Luckily I managed to source a full loom on Facebook market place that I could chop up and make use of. 
 

I would be happy to pay more than £23.00 for a decent lock but £200 is pushing it a bit. The other 3 locks are Chinese so it is a bit of a waiting game.

 
Not sure where to locate locks that will be reliable though. 

 

Thanks for your all your help,

Peter 

 

1 hour ago, prt57 said:

Not sure where to locate locks that will be reliable though. 

 

 

Try https://www.stevensvwspares.com/ normally have a good stock of genuine parts at decent prices and fast delivery 

Thank you for the link. I’d looked at that site just today so I might buy some other replacements as stock for the future. 

 

I need the under bonnet insulation for a Mk 4 Golf as well now. Not sure how they would post that out as it is a flat sheet and could not be rolled up. 

13 hours ago, prt57 said:

I need the under bonnet insulation for a Mk 4 Golf as well now. Not sure how they would post that out as it is a flat sheet and could not be rolled up. 

I've just bought the under bonnet insulation for an Octavia 3 from eBay, that's a flat sheet but arrived as a roll via Evri and on unrolling went perfectly flat again.