Central locking cycling on startup

D

davenportmb

Member
Hello all. I've got a 2001 1.4TDi 75 which has been giving me a headache.

When you jump in the car after it's been left for a period of time and start it up the central locking starts cycling. I think that it's constantly trying to unlock the doors because I can open the driver's door at any point during the cycling without problem.

While the locks are cycling I can press the door lock button on the drivers door but the doors do not lock and the red light on the button doesn't come on.

At the same time, if the headlights are on, I've noticed that the lit icons around the headlight switch flicker.

The central locking continues for about 30-60 seconds and then stops. Once the locks have calmed down, the lights on the headlight switch go steady and I can lock the doors using the door lock button and its red light comes on.

Does anyone have an idea what it might be? Having read a few previous posts on here I guess it might be the CCCU - can anyone else with more experience confirm or suggest an alternative I've missed?

Really keen to get this sorted as cheaply as possible. If anyone could recommend someone in and around South West London (Tooting) that would be great. I've been using Peter Norris in Clapham and, while I'm happy with their service, I literally can't afford any more bills on this car right now!
 
It does seem to be a possible sign of a CCCU problem. Does everything else work as it should?
Remote locking? Alarm? windows?

Steve B
 
Hi Birchall - Apart from the weird cycling, the remote locking is working as intended. I've checked all doors and they lock and unlock as they should. No problems with the alarm and the electric front window (rears are winders) work well though the one-press up occasionally hiccups where it stops and winds down a little. Another press and it goes right up. Now that I think about it - there's a strange whirring noise coming from the dash when all the lock cycling is happening. I suspect it's the climate control being weird.

Hello Bretti - I don't have a VCDS so don't have any error messages to share. As someone who is concerted to do work on his A2 to cut down on garage bills, is it worth buying the KII-USB interface and VCDS? £175 ($250) sounds like a lot but given how much could save in servicing might it be worth it?
 
davenportmb said:
Hi Birchall - Apart from the weird cycling, the remote locking is working as intended. I've checked all doors and they lock and unlock as they should. No problems with the alarm and the electric front window (rears are winders) work well though the one-press up occasionally hiccups where it stops and winds down a little. Another press and it goes right up. Now that I think about it - there's a strange whirring noise coming from the dash when all the lock cycling is happening. I suspect it's the climate control being weird.

Hello Bretti - I don't have a VCDS so don't have any error messages to share. As someone who is concerted to do work on his A2 to cut down on garage bills, is it worth buying the KII-USB interface and VCDS? £175 ($250) sounds like a lot but given how much could save in servicing might it be worth it?
Click to expand...


It could be down to problems with the microswitches in the door locks, I am no expert in that area but if you google "A2OC door micro" you should find some useful info. (EDIT - Sorry Bretti, I have only just seen that you posted that before I posted mine - sorry)


Steve B
 
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I'd also agree that microswitches in the door locks are at fault here. A scan of the car using VCDS should pinpoint the door(s) causing the issues. :)

The microswitches can potentially be repaired, but it's a somewhat labour intensive job as the door has to be partially stripped down and then the lock mechanism must be disassembled once removed.

A scan is the best way to start though! :)

Regards,

Matt.
 
Thanks for the advice, guys. I have found the door switch guides in the forum and ordered a Gendan Vag-Com USB cable. Once that's arrived I'll use the VCDS-Lite shareware to do a scan and take it from there.

If trying to test the microswitches and - if necessary - fit new ones is a bit fiddly, would it be better to just buy a new lock assembly and just switch it out? Better yet, does anyone know a firm that does an exchange service? That said, I guess they'd have to send the new lock first otherwise you have an unsecured and unroadworthy car for three-four days!
 
Update!

So my Gendan Vag-Com USB cable arrived and I found a moment today to hook it up and do a quick scan of my car. I got the following:

01330 - Central Control Module for Central Convenience (J393)
37-00 - Faulty
01331 - Door Control Module; Driver Side (J386)
49-10 - Please Register/Activate - Intermittent
01370 - Alarm triggered by Interior Monitoring
35-00
01572 - Alarm triggered by Door Contact Switch; Passenger Side
35-00 - Please Register/Activate
01561 - Left Rear Door
61-00 - Won't De-Safe
01562 - Rear Right Door
59-00 - Please Register/Activate
01562 - Rear Right Door
61-00 - Won’t De-Safe
00947 - Trunk Lid remote Control Switch (E188)
27-10 - Implausible Signal - Intermittent

So, it looks like the CCCU is on its way out. I've had the carpet up and taken a look: it's coded 8Z0 959 433 Q

With that in mind, I have two questions:

1. Would a faulty CCCU be the cause of the other faults listed there or could it be likely that both the CCCU and the microswitches are shot?
2. @Timmus: Seems that you're the man to speak to regarding replacements. Is that still the case? I just want to make sure that you're still offering this service.

Thanks to everyone for your help so far.
 
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davenportmb said:
So my Gendan Vag-Com USB cable arrived and I found a moment today to hook it up and do a quick scan of my car. I got the following:

01330 - Central Control Module for Central Convenience (J393)
37-00 - Faulty
01331 - Door Control Module; Driver Side (J386)
49-10 - Please Register/Activate - Intermittent
01370 - Alarm triggered by Interior Monitoring
35-00
01572 - Alarm triggered by Door Contact Switch; Passenger Side
35-00 - Please Register/Activate
01561 - Left Rear Door
61-00 - Won't De-Safe
01562 - Rear Right Door
59-00 - Please Register/Activate
01562 - Rear Right Door
61-00 - Won’t De-Safe
00947 - Trunk Lid remote Control Switch (E188)
27-10 - Implausible Signal - Intermittent

So, it looks like the CCCU is on its way out. I've had the carpet up and taken a look: it's coded 8Z0 959 433 Q

Would a faulty CCCU be the cause of the other faults listed there or could it be likely that both the CCCU and the microswitches are shot?
Click to expand...

Hello,

I've highlighted in bold what I believe to be the cause of the problem. These "won't de-safe" faults are indicative of failed microswitches, and failed microswitches are by far the most common cause of the cycling central locking.

That your CCCU has thrown up the 01330 fault is unfortunate as it clouds the issue somewhat and doesn't allow us to be 100% conclusive in our diagnosis. However, early CCCUs have been known to report the 01330 fault but exhibit no symptoms of failure. As such, without getting stuck in, it's difficult to make any further progress, but I'd be inclined to treat the locks as Suspect Number 1 and the CCCU as Suspect Number 2.

I'll send you a PM about the CCCU replacement service. :)

Cheers,

Tom
 
Thanks for the advice. I shall look at the microswitches as a priority and the CCCU as a secondary issue.

In terms of trying to establish for definite whether the CCCU is on its way out, when I did the VAG-COM scan I wasn't able to connect to the Auto HVAC channel. It would have three or four attempts and then throw up a warning error saying "Too many communications errors!"

If the CCCU also controls the HVAC, could this VAG-COM error message be the result of a failing CCCU?

@YorkshireHill Thanks - will send you a PM.
 
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The saga continues...

Last weekend I pulled the rear door locks out and cleaned up the wired microswitches before refitting. This appears to have fixed the driver-side rear door but the passenger-side is still cycling (along with the front passenger door now - smashing).

I've had the offending rear lock out again today and I've got it on the table. I soldered in a new wired microswitch this morning but after doing a test refit it's still cycling when the ignition is turned on.

I've pulled out a multimeter and tested the resistance through the microswitch and the two other switches soldered to the circuit board marked on the image below.

lock.jpg

Switch 1 (the new microswitch) is giving me a consistent reading of 1.4 ohm when engaged.

Switch 3 is giving me a resistance of 1.6 ohm when the switch is not engaged, and between 1.8-2 ohm when the switch is engaged (measured of the other contact point). Again, pretty consistent.

Switch 2, on the other hand, gives me a steady reading of 3.9-4.2 ohm when the switch is engaged but, when the switch is not engaged I get readings all over the place - anything between 4-24 ohm - and get a different reading each time I test after pressing and releasing the switch.

By nature of its inconsistency I'm starting to think that switch 2 might be the problem.

1. Am I completely wrong with my assumption that the second switch is causing the problems? Are those resistance readings still within acceptable tolerances?
2. Can the onboard switches be purchased separately, like the wired microswitch?
3. Is it worth sacking this lock off and just buying a new unit from Stoke Audi for £100? (Ouch!)

Thanks for any advice you can offer - hope you're all enjoying your Saturdays!
 
Hi,

I can't comment on the microswitches, other than to say that the readings from switch 2 do look to be an issue.

But you might have two separate issues, the microswitch and the CCCU. Are there any other CCCU type faults? Such as alarm or window motor issues? not the climate (HVAC) thogh, that is not going to be relevant to the CCCU.

Remember that if you were to buy the CCCU and keys (from Hillary for example) your money would not be wasted. If it makes no difference to your problems then you can sell it on without losing any money (they are popular parts).

I am sure that Matt or someone else who also understands the operation of the microswitches will be along shortly.

Steve B
 
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Thanks, Birchall. I've not noticed any other problems with the electric windows or with the alarm - it's just that 01330 fault code that I'm getting on the scan.

I'll have a think on it for a few days and update when I've made my next move - hopefully this thread will prove useful for someone later on!
 
Hi Davenportmb,

As has been mentioned above, the issue is still likely to be caused by microswitches. :p

To answer your questions:

1. Your assumption is right, the second switch will be causing problems. The resistance should be steady and a low value. I'll explain a potential fix below.
2. I don't think they can be bought separately easily, certainly not from Audi. I believe a member on here had found a source, but I can't remember the outcome.
3. Keep the lock, it's likely repairable.

For how you have attempted to fix the lock so far, have you physically cleaned the wired microswitch? Have I understood correctly?

Regarding the likely and potential fix, I think your wavering resistance values are due to poor connections between the soldered pins of the switches and the printed circuit board of the lock. There's more information in this thread.

You'll need a soldering iron and likely some solder to do this. To put simply, you need to 'reflow' each of the joints on the board adding small amounts of solder as necessary. This will re-establish the connections and should give stable resistance readings.

Don't worry about the 01330 fault code, as Timmus has said, this is sometimes shown when there is no fault.

Hopefully you can get this fixed! :)

Regards,

Matt.
 
Thanks, Spike - that's the company from which I bought my new wired microswitches. They fit perfectly.

Hi Wilco - thanks for the advice. I took the lock out again this afternoon and re-soldered the connections on switch 2. Sadly, I'm still getting inconsistent and wide-ranging resistance readings. I flipped the circuit board over and checked the resistance again through the switch's actual connections and the readings are similar so it's definitely the switch, not the solder. I can't see a way to open the switch up so that I can clean it with electrical solvent cleaner

I'm going to have a look through the forums and see if I can find that reference to replacement switches you mention. If I have no luck then I'll either see if I can find a secondhand unit cheap enough to take a chance on or just stump up the cash for a new unit.

Thanks to everyone for your help with this! This forum is a fantastic source of information and I'm proud to be a supporter.
 
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