Deeper dive into these fault codes

[CJW]

Hi. For the year I’ve had this T6, there have always been two two faults codes from Carista:

05273
05459

The van runs and starts like a dream. @mmi rightly suggested this:

Carista might have padded the fault codes by leading zeros thus turning the actual codes to something different. I would verify the codes with a proper tool.

Meanwhile, I would guess the codes actually are:

5273 - Output for Starter Relay - P0616 00 [032] - Short to Ground​

5459 - Control Circuit for Starter Relay 2 - P3048 00 [032] - Short to Ground​

​

So simply intermittent low voltage (which looks like a short to ground) during cranking (poor battery perhaps)​

​

For Transporter e.g. here:​

Transporter t6 bcm problem

hi lads/ladys , l have a customer with a t6 VOLKSWAGEN TRANSPORTER T28 TDI P/V TRENDLINE BMT VIN: WV1ZZZ7HZGH129480 Bhp: 101 Reg Date: 28/06/2016 Engine Code: CAAB he bought van with with faulty bcm he thought and ask me to program in new one . he has bought one with all the same numbers, l...

forums.ross-tech.com

​

I had the battery tested and it’s tip-top. I’m aware that these might be ghost codes from Carista, but don’t have VCDS.

The codes have been nagging me though.

Then I noticed that @mmi and @Loz had diagnosed a similar fault code as being an immobiliser:

25665 - Output for Starter Relay - P0615 00 [032] - Open Circuit
25670 - Control Circuit for Starter Relay 2 -- P3049 00 [032] - Open Circuit

That’ll be the immobiliser, they have tapped into the bcu feed that goes through the 5a fuse that supplies the 2 starter relays.

So I wonder - since it’s ex-fleet, if there might be some relic of a second immobiliser. I’m going to have a look under the battery tomorrow to see what I can find. Does anyone know what I should keep an eye open for? I was thinking a relay that isn’t part of the OEM relay suite, extra cables.

 

[CJW]

I’ve read that some immobilisers replace the starter fuse with a remote switch, so will look for inserts into the fuse holder bank.

 

[CJW]

Finally got round to this today. No evidence of anything non-factory under the battery. Hmmm. Will wait til I get VCDS then see what that can tell me with some block measuring.

 

[roadtripper]

The thing is if they were valid codes for the starter relays then you wouldn't be able to start the engine?

 

[CJW]

The thing is if they were valid codes for the starter relays then you wouldn't be able to start the engine?

It is really weird. I really thought @mmi nailed it early on with the poor battery but it starts every time like a dream. 3rd stroke it’s there. Reliable as hell.

And the battery test was good. ¯\_(ツ)_/¯

 

[mmi]

The thing is if they were valid codes for the starter relays then you wouldn't be able to start the engine?

Most likely they are valid codes. However, the codes provided by Carista actually miss crucial information - the current status of the fault - is the fault active (currently present) or a thing in the past. Could also have been just glitch which was not even noticeable at driver's seat.

Will wait til I get VCDS then see what that can tell me with some block measuring.

VCDS will capture more details what's going on timewise - even down to statuses of individual starter relays. However, only VCDS HEX-V2 or HEX-NET are fast enough to capture such quick events.

IDE07834-MAS09443	Status of starter activation relay-Relay 1 activated	not active
IDE07834-MAS09444	Status of starter activation relay-Relay 2 activated	not active

Besides the above there are 29 more data items having word "starter" in their description.



A snippet using a few of the above


- from thread

Intermittent starting issue

That's interesting... I was wrong, captured some logs on my way to the office this morning and the fuel pressure does drop when the stop start kicks in. Will post the log when I'm home this evening. Edit: Log now attached, 3 separate stop/start events captured.

www.t6forum.com

 

[CJW]

Most likely they are valid codes. However, the codes provided by Carista actually miss crucial information - the current status of the fault - is the fault active (currently present) or a thing in the past. Could also have been just glitch which was not even noticeable at driver's seat.



VCDS will capture more details what's going on timewise - even down to statuses of individual starter relays. However, only VCDS HEX-V2 or HEX-NET are fast enough to capture such quick events.

IDE07834-MAS09443	Status of starter activation relay-Relay 1 activated	not active
IDE07834-MAS09444	Status of starter activation relay-Relay 2 activated	not active

Besides the above there are 29 more data items having word "starter" in their description.
View attachment 213010


A snippet using a few of the above

View attachment 213011
- from thread

Intermittent starting issue

That's interesting... I was wrong, captured some logs on my way to the office this morning and the fuel pressure does drop when the stop start kicks in. Will post the log when I'm home this evening. Edit: Log now attached, 3 separate stop/start events captured.

www.t6forum.com

Hi @mmi I intend to get the Hex-V2 model, so thank you very much for the data items. I’ll do some tests when it arrives based on these.

 

[CJW]

Hi @mmi and @n10n

I've now got the Hex-V2. After making a backup of the first scan, then clearing codes (which VCDS is much better at than Carista BTW), there are just those pesky two engine 'faults' left that I can't account for. The other faults relate to the fact I've upgraded the head unit, I believe.

After clearing the codes, I started the engine, then took another scan, which is attached. I think I gain from this that:

• The faults occur when ignition is on, but before cranking.
• AGM Battery voltage looks OK at 12.380V at rest, which matches the battery health check I had done.
• No issues with the battery regulator being reported.

I looked at the battery coding, and it looked like it had been updated when the battery was changed for a Bosch battery before I owned it. I say this because the serial no of the battery was entered as something like 1111111111.

They're not really faults as the van is an excellent starter - this is just for my curiosity. My next step would be to log data. I think this is what I need to do and I'm asking if this is the best way to do it please:

VCDS > Select Control module > 01-Engine > Advanced Measurement Values > Tick everything relating to starter relay and control circuit 2 (is there a max number?) > Click Log > Start > Start Engine > leave running for a few seconds > stop > stop engine.

Is that right or is there more to it?

Many thanks

Chris

 

[n10n]

Hi @mmi and @n10n

I've now got the Hex-V2. After making a backup of the first scan, then clearing codes (which VCDS is much better at than Carista BTW), there are just those pesky two engine 'faults' left that I can't account for. The other faults relate to the fact I've upgraded the head unit, I believe.

After clearing the codes, I started the engine, then took another scan, which is attached. I think I gain from this that:

• The faults occur when ignition is on, but before cranking.
• AGM Battery voltage looks OK at 12.380V at rest, which matches the battery health check I had done.
• No issues with the battery regulator being reported.

I looked at the battery coding, and it looked like it had been updated when the battery was changed for a Bosch battery before I owned it. I say this because the serial no of the battery was entered as something like 1111111111.

They're not really faults as the van is an excellent starter - this is just for my curiosity. My next step would be to log data. I think this is what I need to do and I'm asking if this is the best way to do it please:

VCDS > Select Control module > 01-Engine > Advanced Measurement Values > Tick everything relating to starter relay and control circuit 2 (is there a max number?) > Click Log > Start > Start Engine > leave running for a few seconds > stop > stop engine.

Is that right or is there more to it?

Many thanks

Chris

Hi,

That’s it basically.

You can measure maximum 12 parameters at a time. Do check ”Group UDS requests” and select ”by 7” from dropdown - this will optimize queries and provide best sample rate.


The faults are marked intermittent - they might develop into actual faults if they continue to occur or be eventually cleared automatically if the problem goes away. Freeze frame bits probably tell something but unfortunately I have no idea what exactly.

Pure guess but ”output of starter relay - short to ground” sounds to me like the starter would be bit slow to start cranking. There’s a huge surge of current passed through starter brushes momentarily before the starter turns and gains speed, this could very well look like a short if it takes any longer than what is considered normal.

 

[CJW]

Than

Hi,

That’s it basically.

You can measure maximum 12 parameters at a time. Do check ”Group UDS requests” and select ”by 7” from dropdown - this will optimize queries and provide best sample rate.

View attachment 215492
The faults are marked intermittent - they might develop into actual faults if they continue to occur or be eventually cleared automatically if the problem goes away. Freeze frame bits probably tell something but unfortunately I have no idea what exactly.

Pure guess but ”output of starter relay - short to ground” sounds to me like the starter would be bit slow to start cranking. There’s a huge surge of current passed through starter brushes momentarily before the starter turns and gains speed, this could very well look like a short if it takes any longer than what is considered normal.

Thanks for the fast reply - much appreciated.

 

[roadtripper]

I'm sure I remember reading in a thread here recently that the "short to ground" faults can also be a lack of voltage - so the assumption is there is a short somewhere.

Doesn't seem like there is given that it starts well, but possibly in the life as a fleet van some wiring was altered in such a way it works fine electrically but the BCM can no longer measure the voltage?

 

[CJW]

I'm sure I remember reading in a thread here recently that the "short to ground" faults can also be a lack of voltage - so the assumption is there is a short somewhere.

Doesn't seem like there is given that it starts well, but possibly in the life as a fleet van some wiring was altered in such a way it works fine electrically but the BCM can no longer measure the voltage?

Yes I wondered that. I removed all wiring myself and there wasn’t anything obvious. I looked under the battery recently to see if there was any kind of starter switch that was perhaps a proprietary immobiliser but it all looks factory to me.

 

[n10n]

After checking some wire diagrams looks like the high current relay is in the starter itself and starter relays 1 and 2 in the ebox just provide feed for the starter solenoid but not the cranking power.

If I read diagrams right starter relays are driven by ECU in the ebox, and relay 2 (J907) output has an extra wire that goes to the ECU, BCM and voltage stabiliser. The symbol within relay looks kind of like a potentiometer but without control arm linked - I think this is the measurement wire.

Terminal 1 - GND
Terminal 2 - ECU
Terminal 5 - Starter solenoid
Terminal 3 - Starter relay 1
Terminal 6 - ECU, BCM and voltage stabilizer

 

[CJW]

After checking some wire diagrams looks like the high current relay is in the starter itself and starter relays 1 and 2 in the ebox just provide feed for the starter solenoid but not the cranking power.

If I read diagrams right starter relays are driven by ECU in the ebox, and relay 2 (J907) output has an extra wire that goes to the ECU, BCM and voltage stabiliser. The symbol within relay looks kind of like a potentiometer but without control arm linked - I think this is the measurement wire.

Terminal 1 - GND
Terminal 2 - ECU
Terminal 5 - Starter solenoid
Terminal 3 - Starter relay 1
Terminal 6 - ECU, BCM and voltage stabilizer

View attachment 215495

Thanks @n10n - that’s an interesting line of enquiry. I’ll figure out where the starter motor is and see if the cabling is good.

 

[n10n]

Thanks @n10n - that’s an interesting line of enquiry. I’ll figure out where the starter motor is and see if the cabling is good.

The faults don't really tell us other than (as I understand it) ECU doesn't see the voltages it expects from the pin 6 of J907 relay.

So, the issue could be

1) within relay itself
2) wiring from relay pin 6 to ECU or BCM
3) wiring from relay pin 5 towards starter solenoid or the solenoid itself
4) wiring from relay pin 3 towards relay 1

As the van starts fine I would look into 2) and 1) first.

As for VCDS, you should be able to observe what leads to the faults, somehow. The names are difficult to relate with wires and physical world but I would try to see inconsistencies between these ones:

IDE00412,Starter control: terminal 50,not active,
IDE00416-MAS07386,Starter control: terminal 50 feedback-Terminal 50 on CAN,not active,
IDE00416-MAS09391,Starter control: terminal 50 feedback-Terminal 50 via cable,not active,
IDE00416-MAS09392,Starter control: terminal 50 feedback-Starter relay,not active,
IDE00416-MAS09394,Starter control: terminal 50 feedback-Starter operation read back wire T50Ret,not active,

Also BCM (Central electrics 09) has terminal 50 status on measuring block channel 1 - you can't log it at the same time with others but worth checking that goes high as well during cranking. The faults are from ECU though.

 

[CJW]

Thank you so much @n10n - hopefully will have chance to look at this on Sunday. I’ll keep you posted.

 

[CJW]

Hi @n10n, I ran a test and got the following results output as a CSV. I understand the data (the timestamp, location, and what feedback bits are) but I guess the next step is to somehow find out what each bit refers to. What's the normal way of looking these up please? Do I need to do a blockmap capture over a similar cycle and see if I can see a correlation? Is that the normal way? Many thanks

[EDIT : I did a blockmap capture and it's obviously not going to give me the bit definitions - interesting reading though]

 

[n10n]

Hi @n10n, I ran a test and got the following results output as a CSV. I understand the data (the timestamp, location, and what feedback bits are) but I guess the next step is to somehow find out what each bit refers to. What's the normal way of looking these up please? Do I need to do a blockmap capture over a similar cycle and see if I can see a correlation? Is that the normal way? Many thanks

View attachment 215691

Hi,

Your guess is as good as mine, I haven’t played much with status bit measuring values. Probably there is some kind of logic, either based on MAS number or the ordering in VCDS but I just don’t know it. Would @mmi have any insight into this?

What I can do though is to log the same (will do still today) and maybe we can spot some differences - not sure if this helps any but might build the collective knowledge.

Also I do note that CSV column names look very much like what was reported in fault freeze frames - if we can figure the bits out we should gain some ability to interpret freeze frames as well

 

[CJW]

In one sense I'm relieved I hadn't missed something obvious I read the VCDS manual but it's hard going and I think I'll have to revisit some parts.

Yes - the freeze frame looks very similar. Thank you for this - would be interesting to see an ignition cycle from a vehicle that doesn't report the fault.

Thank you

 

[CJW]

Looking at the freeze frames, most of the action is in the 'release conditions':

Starter control: terminal 50 feedback-Bits 0-7: 0
                    Starter control: relay 1-Bits 0-7: 0
                    Starter control: release conditions-Bits 0-7: 2
                    Starter control: release conditions-Bits 0-7: 86
                    Starter control: shut-off conditions 1-Bits 0-7: 0
                    Starter control: shut-off conditions 1-Bits 0-7: 0

Which has a value of 86 so quite a few bits active. I assume the 'release conditions' is a checklist of conditions that must be satisfied before the starter motor stops and the ICE takes over.

Should I run the test again and include 'Release Conditions' this time?