Erroneous alarm triggers [Resolved]

[FYPO]

I purchased a used T6 for my business a couple of months back, and it's giving us some real issues. It has been back with the dealer three times each for a week visit; due to the alarm sounding for no apparent reason.

There was an issue with the starter battery that I pointed out the first time it went back; the voltage never went above 11.8v. So they 'conditioned' the battery, confident that it would fix the alarm, but it did not. The battery didn't hold the charge.

Van went back in, and they agreed to a new battery, I went to collect it after the weekend, and I caught the workshop having to jump start it. They sent me away again so they could look further. They then replaced the alternator and the alarm sounder. They still had issues with the alarm, so they replaced the alarm sounder a second time, we collected it yesterday. 4 AM alarms going off again.

We have noticed that when we lock the van the alarm LED is solid for the 30s before starting to flash. We also had an issue with the roof rack the can came with, it had the typical issue when poorly fitted, the rain came through the bolts. The cab floor mat was sodden, not sure if a short in the cabling under the mat could be causing the issue?

Has anybody had a similar issue or got any ideas because the dealer isn't very helpful...?

 

[Salty Spuds]

Have you tried setting the alarm with the internal sensors disabled?

 

[FYPO]

Have you tried setting the alarm with the internal sensors disabled?

Yes - Sorry I should have added this. Internal sensors disabled and the alarm will still sound.

 

[Dellmassive]

I think you need to take it to a different garage for a second opinion.

It's obviously being miss diagnosed.

It's sounding like a current drain somewhere....?

Causing the battery drain.

 

[Salty Spuds]

Yes - Sorry I should have added this. Internal sensors disabled and the alarm will still sound.

Could be worth getting a VCDS scan, IIRC it will tell you what triggered the last alarm.

 

[DXX]

The garage doesn’t seem too switched on. Changing the alarm sensor twice! What’s the chance of a new alarm sounder being defective?
The alarm sounder doesn’t sound without a trigger signal, highly unlikely it’s the sounder.
I’m guessing they are more car sales than motor repairs.

 

[Spaghetti]

I purchased a used T6 for my business a couple of months back, and it's giving us some real issues. It has been back with the dealer three times each for a week visit; due to the alarm sounding for no apparent reason.

There was an issue with the starter battery that I pointed out the first time it went back; the voltage never went above 11.8v. So they 'conditioned' the battery, confident that it would fix the alarm, but it did not. The battery didn't hold the charge.

Van went back in, and they agreed to a new battery, I went to collect it after the weekend, and I caught the workshop having to jump start it. They sent me away again so they could look further. They then replaced the alternator and the alarm sounder. They still had issues with the alarm, so they replaced the alarm sounder a second time, we collected it yesterday. 4 AM alarms going off again.

We have noticed that when we lock the van the alarm LED is solid for the 30s before starting to flash. We also had an issue with the roof rack the can came with, it had the typical issue when poorly fitted, the rain came through the bolts. The cab floor mat was sodden, not sure if a short in the cabling under the mat could be causing the issue?

Has anybody had a similar issue or got any ideas because the dealer isn't very helpful...?

The solid illumination to the door LED indicates a fault. I had that on my van and it was the ultrasonics not being plugged in.

I’ve had false alarms when there’s been a moth in the van, but you say that you’ve turned off the ultrasonics.

Do you get any flickering on the ‘open door’ indicators when using the van? Could the micro switches have water ingress causing a slight change in resistance so that the van thinks the door has been opened?

Have you managed to see a scan of the van?

 

[FYPO]

u need to take it to a different garage for a second opinion.

It's obviously being miss diagnosed.

It's sounding like a current drain somewhere....?

Agreed - I may now take it to an independent VW Specialist to diagnose. I am also considering buying VCDS; I'm happy to repair the issue myself. I've just got to find what is causing the problem.

I'm not sure there is a current drain, but I'll add it to my diagnostic list. I have an idea that the BCM could be the issue. I assume that controls the smart alternator and the alarm?

Could be worth getting a VCDS scan, IIRC it will tell you what triggered the last alarm.

Yeah, I may bite the bullet and buy VCDS.

The garage doesn’t seem too switched on. Changing the alarm sensor twice! What’s the chance of a new alarm sounder being defective?
The alarm sounder doesn’t sound without a trigger signal, highly unlikely it’s the sounder.
I’m guessing they are more car sales than motor repairs.

They are a main dealer. I agree, though. Nobody seems to diagnose the issue, switch parts, and hope.

The solid illumination to the door LED indicates a fault. I had that on my van and it was the ultrasonics not being plugged in.

I’ve had false alarms when there’s been a moth in the van, but you say that you’ve turned off the ultrasonics.

Do you get any flickering on the ‘open door’ indicators when using the van? Could the micro switches have water ingress causing a slight change in resistance so that the van thinks the door has been opened?

Have you managed to see a scan of the van?

I have checked the connector in the rear pillar on the passenger side for any corrosion or poor connection. The dealer says nothing comes up on the scan to say why the alarm is sounding.

 

[Spaghetti]

My concern with ‘nothing showing’ on the scan from the dealer is that if the van thinks the door has been opened due to water in a micro switch causing high resistance, then the van won’t think that’s a fault, just that the door has been opened…..

 

[FYPO]

So, I got to have a look at the van this afternoon, plugged it into Carista to read for any error codes. Three there that I know are caused by an aftermarket head unit but also noticed it couldn't connect to the Central Electronics ECU. I disconnected the battery and did a capacitive discharge to try and hard reset the electronics.

After this, Carista connected to Central Electronics ECU and came up with the following errors:

03433 - Terminal 30 for Reverse Driving-Lights / Turn Left
03442 - Feedback Lock-Position Trunk
03585 - Terminal 30 for Wiper
01134 - Alarm Horn (H12)
03021 - Local databus 3

Does anyone have any ideas? The dealer has asked me to come in tomorrow to chat with the 'Master Tech', so hopefully, he sees the same errors!

 

[mmi]

The dealer says nothing comes up on the scan to say why the alarm is sounding.

As @Salty Spuds mentioned the BCM has a log which tells exactly what triggered the alarm and time (the last 4 events). The alarm is not recorded as fault.
The log can be decoded by e.g. VCDS. Also dealer's tool has the capability.
The log is stored in BCM's "measurent blocks" 20-23.
The decode spreadsheet is here - an attcahment - T6_09_BCM_Measurement_Groups_(T6Frelease_1b).xlsx:

VCDS codes list

Posting this here as I believe it contains codes previously undocumented on the forum. It comes from the the OBDeleven forum, with extra functions added to the list by the poster Oberon. I'm posting as is and take no responsibility for the accuracy of the data. Central electrics control unit...

www.t6forum.com

 

[ei-aprilia]

I had this same issue on my T5 , sodden floor and alarm going off. There's an earth under the driver's seat under the carpet and it had corroded. It's a fairly common fault on T5s I'd imagine the T6s have a similar wiring loom so worth a look.

 

[JOG]

I had this same issue on my T5 , sodden floor and alarm going off. There's an earth under the driver's seat under the carpet and it had corroded. It's a fairly common fault on T5s I'd imagine the T6s have a similar wiring loom so worth a look.

Good thinking!

 

[FYPO]

As @Salty Spuds mentioned the BCM has a log which tells exactly what triggered the alarm and time (the last 4 events). The alarm is not recorded as fault.
The log can be decoded by e.g. VCDS. Also dealer's tool has the capability.
The log is stored in BCM's "measurent blocks" 20-23.
The decode spreadsheet is here - an attcahment - T6_09_BCM_Measurement_Groups_(T6Frelease_1b).xlsx:

VCDS codes list

Posting this here as I believe it contains codes previously undocumented on the forum. It comes from the the OBDeleven forum, with extra functions added to the list by the poster Oberon. I'm posting as is and take no responsibility for the accuracy of the data. Central electrics control unit...

www.t6forum.com

Took the van in today to have a look at the diagnostics. We looked at the last 4 activations all showing as activated by H12 Alarm Horn. We also noticed the battery was low again (around 12.2v). Running the engine brought the voltage up to 13.4v.

Tech told me he reprogrammed the BCM last time and the voltage shot up to 14.+V, he wanted to do that again. It didn't fix it this time but showed an issue with module 61 - Battery Regulator. He wants to swap that ??? first before replacing the whole BCM.

I had this same issue on my T5 , sodden floor and alarm going off. There's an earth under the driver's seat under the carpet and it had corroded. It's a fairly common fault on T5s I'd imagine the T6s have a similar wiring loom so worth a look.

That's a good shout, I know where that earth is, ill give it a try!

 

[mmi]

Took the van in today to have a look at the diagnostics. We looked at the last 4 activations all showing as activated by H12 Alarm Horn.

So it looks like the culprit is somehow related to Alarm Horn. A kind of interesting thing that an alarm source is the Alarm system itself - perhaps to prevent tampering with the system.
Anyways, looks like the fault 01134 is related. The fault codes include also a descriptor about the details of the fault. Unfortunately Carista doesn't reveal these.

E.g. the following for the 01134.​

01134 - Alarm Horn (H12) - 000 - -​

01134 - Alarm Horn (H12) - 002 - Lower Limit Exceeded​

01134 - Alarm Horn (H12) - 004 - No Signal/Communication​

01134 - Alarm Horn (H12) - 008 - Implausible Signal​

01134 - Alarm Horn (H12) - 012 - Electrical Fault in Circuit​

01134 - Alarm Horn (H12) - 014 - Defective​

he reprogrammed the BCM last time and the voltage shot up to 14.+V, he wanted to do that again. It didn't fix it this time but showed an issue with module 61 - Battery Regulator.

Please clarify - because the voltage didn't raise to 14V+ indicates a fault in 61-Battery Regulator??? or in the BCM???

Yeah, I may bite the bullet and buy VCDS.

Please do

 

[ei-aprilia]

Central locking not working 24 Jan 2010

 

[ei-aprilia]

Been thinking about this today and this was my issue . It wasn't the earth but a joint further down the loom. I didn't have central locking issues as per the posts in the link but the alarm was going off randomly usually early hours of the morning . I remember stripping the loom back now and finding that corroded joint .

 

[FYPO]

Right, now we are sure this is fixed I’ll update the thread just incase anyone else has the same issue in the future.

The fault was…. Steering wheel angle sensor…

The dealer had to contact VW support team that had them make up a loom to bypass different sensors. They eventually found it was the steering wheel angle sensor. Replaced it and we haven’t had a single issue in a month!

Apparently there are still a number of sensors that aren’t integrated with BCM so won’t have a fault code if they fail. So the module it’s connected to shows a generic fault.

Tech wasn’t very pleased, he’d spent days on the van to find out it would have been a 20min part swap. He was relieved to get rid of the van out the workshop though

 

[Sackmycook]

Right, now we are sure this is fixed I’ll update the thread just incase anyone else has the same issue in the future.

The fault was…. Steering wheel angle sensor…

The dealer had to contact VW support team that had them make up a loom to bypass different sensors. They eventually found it was the steering wheel angle sensor. Replaced it and we haven’t had a single issue in a month!

Apparently there are still a number of sensors that aren’t integrated with BCM so won’t have a fault code if they fail. So the module it’s connected to shows a generic fault.

Tech wasn’t very pleased, he’d spent days on the van to find out it would have been a 20min part swap. He was relieved to get rid of the van out the workshop though

Great info and glad you got it sorted in the end.