Longitudinal Acceleration Sensor (G251)

[Mudwallower]

Hello all. My 2012 T5.1 LWB DSG has gone a bit wonky. The ABS light has come on and my local garage advise a new ABS Module at a cost of £2k plus.
I bought the VCDS from Gendan and my scan said -
1 Fault Found:
01279 - Longitudinal Acceleration Sensor (G251)

What is it and more importantly where is this located on the Transporter ? I can find no definite reference anywhere on the internet.
Has anyone else ever encountered one and successfully replaced them ?

Many thanks in advance

 

[n10n]

Garage may well be right, though I can't say with absolute certainty as I don't unfortunately have T5.1 documentation available - just T5 and T6.

T5 had a separate ESP sensor unit G419, which contained sensors G200 (lateral acceleration sender), G202 (yaw rate sender) and G251 (longitudinal acceleration sender). The unit G419 was installed in centre of vehicle in front footwell, under floor mat. G419 connected to ABS module.

T6 documentation doesn't mention either G419 or G251 at all. That doesn't mean the functionality doesn't exist; the sensors may just be integrated within another control unit. ABS control unit would be the logical choice as G419 was previously connected to it. And indeed, T6 ABS module reports longitudinal acceleration values as advanced measuring values:

IDE02271-IDE03660,CAN output signal(s) status-Longitudinal acceleration,0.71875, m/s
IDE04443-IDE04430,Slip control system sensor-Longitudinal acceleration sensor: offset,0.71875, m/s

Maybe take both VCDS full scan and blockmap of 03 ABS and see if you can find any references to G419, G251 or the word "Longitudinal"

 

[Mudwallower]

Garage may well be right, though I can't say with absolute certainty as I don't unfortunately have T5.1 documentation available - just T5 and T6.

T5 had a separate ESP sensor unit G419, which contained sensors G200 (lateral acceleration sender), G202 (yaw rate sender) and G251 (longitudinal acceleration sender). The unit G419 was installed in centre of vehicle in front footwell, under floor mat. G419 connected to ABS module.

T6 documentation doesn't mention either G419 or G251 at all. That doesn't mean the functionality doesn't exist; the sensors may just be integrated within another control unit. ABS control unit would be the logical choice as G419 was previously connected to it. And indeed, T6 ABS module reports longitudinal acceleration values as advanced measuring values:

IDE02271-IDE03660,CAN output signal(s) status-Longitudinal acceleration,0.71875, m/s
IDE04443-IDE04430,Slip control system sensor-Longitudinal acceleration sensor: offset,0.71875, m/s

Maybe take both VCDS full scan and blockmap of 03 ABS and see if you can find any references to G419, G251 or the word "Longitudinal"

Thanks for the reply n10n. I did wonder if it was part of the ABS module myself.
I am new to the VCDS so will look into the blockmap you mention. Does the engine need to be running, or does the van need to be moving to capture the live data please ?
Unfortunately the snow on my hill has now blocked me in as, apart from no ABS, the DSG does not want to change gear until 3500 - 4000rpm which will make driving a bit tricky in these conditions today.

 

[n10n]

I am new to the VCDS so will look into the blockmap you mention.

Take a look eg this post for instructions on how to get blockmap files for various modules: ABS/Traction control lights still on

Does the engine need to be running, or does the van need to be moving to capture the live data please ?

Doesn't matter in this case. Generally speaking, you can take blockmaps with ignition on, idling or while driving (please mind safety though). Blockmap means just getting values of all known module diagnostic metrics (known as advanced measuring values in VCDS) in a single go. So there's no just one answer to this - depends on what values you especially want to capture.

Unfortunately the snow on my hill has now blocked me in as, apart from no ABS, the DSG does not want to change gear until 3500 - 4000rpm which will make driving a bit tricky in these conditions today.

Wow... I wonder if this could also be a side effect of the acceleration data missing

 

[Mudwallower]

In response to the advice given by n10n I can post the scan results from yesterday if it is of any help. I also included pics as I am unsure what was best. The dodgy sensor G251 does appear on the scan . I do note that on both my scans the ABS Module has no part number recorded whereas I have seen other peoples scans that reference number J104. I wonder if this is part of the problem ?

 

[Mudwallower]

Take a look eg this post for instructions on how to get blockmap files for various modules: ABS/Traction control lights still on


Doesn't matter in this case. Generally speaking, you can take blockmaps with ignition on, idling or while driving (please mind safety though). Blockmap means just getting values of all known module diagnostic metrics (known as advanced measuring values in VCDS) in a single go. So there's no just one answer to this - depends on what values you especially want to capture.


Wow... I wonder if this could also be a side effect of the acceleration data missing

Thanks again n10n. I have posted a new comment below with the scan and pic snips from it while I try to understand all the blockmap files you mentioned. Its a bit much for me I think lol.

 

[n10n]

Longitudinal acceleration: raw value: 32.767 m/s²

Remarkable acceleration in your van!

Space shuttles reach barely >5 m/s^2 and free fall acceleration is 9.81 m/s^2

Calculating rocket acceleration

How does the acceleration of a model rocket compare to the Space Shuttle? By using the resultant force and mass, acceleration can be calculated.

www.sciencelearn.org.nz

 

[Mudwallower]

Longitudinal acceleration: raw value: 32.767 m/s²

Remarkable acceleration in your van!

Space shuttles reach barely >5 m/s^2 and free fall acceleration is 9.81 m/s^2

Calculating rocket acceleration

How does the acceleration of a model rocket compare to the Space Shuttle? By using the resultant force and mass, acceleration can be calculated.

www.sciencelearn.org.nz

Wow. And that was going uphill lol.
I have the same reading from both scans yesterday, even though I cleared all DTC`s inbetween scans and didn`t move the van.
Hopefully my hill will be clear for me to move the van tomorrow and try further investigations.
Thanks for all the advice.

 

[mmi]

What is it and more importantly where is this located on the Transporter ? I can find no definite reference anywhere on the internet.

T5 had a separate ESP sensor unit G419, which contained sensors G200 (lateral acceleration sender), G202 (yaw rate sender) and G251 (longitudinal acceleration sender). The unit G419 was installed in centre of vehicle in front footwell, under floor mat. G419 connected to ABS module.

T5.1 workshop manual "Transporter 2004 ➤ , Transporter 2010 ➤ Brake systems" mentions for MK25A controller

ESP sensor unit - G419-​

❑ Location: integrated in ESP control unit -J104-.​

❑ Can be checked with ⇒ Vehicle diagnostic tester​

But the chapter doesn't explicitly mention G251.

​

However, for MK25 and MK25E the manual mentions

ESP sensor unit - G419-​

❑ Location: centre of vehicle in front footwell, under floor mat​

❑ Combined lateral acceleration sender - G200- , yaw rate sender - G202- and longitudinal acceleration sender - G251​

​

---

Some similarities below - same main fault code 01279 but different subcode (005 vs. 008)

ABS Module (2014 T5, MK25A)

I have a second hand replacement ABS module and as i need to code it, MK25a Can i copy and paste the original coding then do steering angle calibration or do i have to do Login 11 coding 7 etc as per the Wilki It shows Bosch 5.3 & 7 i think this is 5.1 Saturday,13,May,2023,13:03:26:51242 VCDS...

forums.ross-tech.com

Some more

Search results for query: MK25A 01279

forums.ross-tech.com

 

[Mudwallower]

T5.1 workshop manual "Transporter 2004 ➤ , Transporter 2010 ➤ Brake systems" mentions for MK25A controller

ESP sensor unit - G419-​

❑ Location: integrated in ESP control unit -J104-.​

❑ Can be checked with ⇒ Vehicle diagnostic tester​

But the chapter doesn't explicitly mention G251.

​

However, for MK25 and MK25E the manual mentions

ESP sensor unit - G419-​

❑ Location: centre of vehicle in front footwell, under floor mat​

❑ Combined lateral acceleration sender - G200- , yaw rate sender - G202- and longitudinal acceleration sender - G251​

​

---

Some similarities below - same main fault code 01279 but different subcode (005 vs. 008)

ABS Module (2014 T5, MK25A)

I have a second hand replacement ABS module and as i need to code it, MK25a Can i copy and paste the original coding then do steering angle calibration or do i have to do Login 11 coding 7 etc as per the Wilki It shows Bosch 5.3 & 7 i think this is 5.1 Saturday,13,May,2023,13:03:26:51242 VCDS...

forums.ross-tech.com

Some more

Search results for query: MK25A 01279

forums.ross-tech.com

Many thanks for the advice mmi. My local garage did mention maybe it was all in the ABS module, but they were unsure themselves. They are proper old school mechanics but this new fangled stuff gets them sometimes.
My only worry is my VCDS scans did not pick up a code for the ABS where you mention J104. Maybe that is part of my problem ?
The more I read the more I think I will just go for a new ABS module and hope it fixes it.
I will report back with the results for you all and anyone else who needs the info.
Many thanks to everyone who has helped.

 

[Pauly]

J104 is more of a reference number
Jxxxxx numbers are assigned to components so they can be cross referenced between manuals and documents like workshop manuals and wiring diagrams etc

The part number is listed on your scan 7E0907379K

 

[Pauly]

Have you checked the wiring diagrams to see if it shows any cabling going to the sensors in question ?
That should confirm if it’s internal or external

 

[keith baker]

I had a similar fault with my Skoda Octavia. I sent off the abs unit for refurb but that didn't fix it ( and cost about £400). Eventually found the longitudinal acceleration sensor under the driver's seat. Fitted a secondhand unit for £12 which fixed the problem. I'd say keep looking for this unit first. It was simple to replace with only a couple of wires and 2 nuts. Whereas the abs unit needs full brake bleeding.

 

[mmi]

2012 T5.1

None of those sensors/modules in post #9 are found in the vehicle's wiring diagram.

My only worry is my VCDS scans did not pick up a code for the ABS where you mention J104. Maybe that is part of my problem ?

No, I guess it's just a VCDS label file "7E0-907-37x-MK25AXT.clb" issue as the label file for other platforms with MK25A seem to include that reference number.
E.g.

Address 03: ABS Brakes (J104)       Labels:* 7P0-907-379.clb
   Part No SW: 7P0 907 379 K    HW: 7P0 907 379 A
   Component: MK25A         H36 0418

Address 03: ABS Brakes (-----)       Labels: 7E0-907-37x-MK25AXT.clb
   Part No SW: 7E0 907 379 K    HW: 7E0 907 379 E
   Component: ESP MK25A XT  H43 0110

The selection of the label file is based on Part No. SW which is extracted from the module itself. It seems the "7E0-907-37x-MK25AXT.clb" hasn't been updated since 16.7.2015.

---

Then, of course, the module (with the sensors) are found on T5 (2004-2009) diagram.

 

[n10n]

None of those sensors/modules in post #9 are found in the vehicle's wiring diagram.

Thanks for checking, I think this pretty much confirms the acceleration sensor is integrated in the ABS module.

Then, of course, the module (with the sensors) are found on T5 (2004-2009) diagram.
View attachment 270132

Yes that’s what I was looking at initially and thus thought there was some hope it would have been the same in T5.1.

Even more so today but I think already back in 2010 the plastic module enclosure, connectors, supporting electronics and few meters of wire would have been obscenely expensive as compared to the cost of an actual three-dimensional acceleration sensor. Makes sense it’s directly integrated into some other module.

 

[Mudwallower]

None of those sensors/modules in post #9 are found in the vehicle's wiring diagram.


No, I guess it's just a VCDS label file "7E0-907-37x-MK25AXT.clb" issue as the label file for other platforms with MK25A seem to include that reference number.
E.g.

Address 03: ABS Brakes (J104)       Labels:* 7P0-907-379.clb
   Part No SW: 7P0 907 379 K    HW: 7P0 907 379 A
   Component: MK25A         H36 0418

Address 03: ABS Brakes (-----)       Labels: 7E0-907-37x-MK25AXT.clb
   Part No SW: 7E0 907 379 K    HW: 7E0 907 379 E
   Component: ESP MK25A XT  H43 0110

The selection of the label file is based on Part No. SW which is extracted from the module itself. It seems the "7E0-907-37x-MK25AXT.clb" hasn't been updated since 16.7.2015.

---

Then, of course, the module (with the sensors) are found on T5 (2004-2009) diagram.
View attachment 270132

Thanks all.
Does this then mean if I bite the bullet and order an ABS module I may be lucky and it should fix this ? That is my simple understanding.
Apparently once it is ordered I cannot change my mind.
Ps no stock in UK so will be a delay too.

 

[mmi]

A rebuilt one?

7E0907379K / 10092903353 - Volkswagen TRANSPORTER T5 2.0 T5 ABS (Pump & ECU/Module Combined)

Common Faults: ABS pump and module failure within Volkswagen Transporter T5 vehicles manufactured between 2004-2015 are indic...

www.ecutesting.com

 

[n10n]

If you can wait a while I would take a bit of risk and order a refurbished one from E-bay and have some indie garage fit it. For example ð ð ABS T5 7E0614517A 7E0907379E â â GENERALÃBERHOLT â â | eBay, it shows two part numbers, one is the pump and one is the module - they go hand in hand.

Search by HW number 7E0907379E, there’s others as well, above is just an example.

I think you have been somewhat unlucky (despite of the incredible acceleration), these things are very reliable and hence I think a second hand one is relatively low risk and spares costs significantly. Ofc fitting work will still add to the cost.

Maybe try to check the pump number from your vehicle for match as well before ordering, not sure if there has been many versions.

 

[n10n]

A rebuilt one?

7E0907379K / 10092903353 - Volkswagen TRANSPORTER T5 2.0 T5 ABS (Pump & ECU/Module Combined)

Common Faults: ABS pump and module failure within Volkswagen Transporter T5 vehicles manufactured between 2004-2015 are indic...

www.ecutesting.com

Haha, beat my by few secs!

 

[Mudwallower]

Haha, beat my by few secs!

I was intending to buy a new one. Expensive I know, but at least it should work.
Will a second hand part need coding ?