Where to find MVB for 2015 NAR Jetta exterior trunk release switch?

Hello All:

I am troubleshooting a new 2015 Jetta (Canadian spec) equipped with keyless access. The car presents an intriguing (and perplexing) fault: The exterior trunk release operates intermittently, but predictably intermittently.

If the car has been used (woken up) within the past 2 minutes or so, and the car is subsequently locked, the trunk can be opened by pressing the exterior trunk release above the licence plate, as long as there is an authorized key within range. But, if the car has been locked for more than about 2 minutes, there is no response after pressing the exterior trunk release with an authorized key nearby. It is necessary to repeatedly press the exterior trunk release (generally about 7 to 10 attempts) before the trunk will unlock.

My first suspicion was that there was a fault with the KESSY (controller 07, the J523), and this controller was replaced and all the appropriate re-adaptation and re-authorization of keys was carried out at the VW dealer. But, the problem remained, with behaviour unchanged. All the wiring related to the exterior trunk release, including grounds, has been checked and found to be in order.

I want to rule out any physical fault with the exterior trunk release switch (i.e. intermittent switch operation) before pursuing further fault-finding. But, I'm not yet fully familiar with the 2015 products, and I know that the central electrical controller on my 2015 Golf (a different car) is about equal in complexity to the Starship Enterprise.

Does anyone know where the MVB that shows exterior trunk release switch status (operated / not operated, etc.) is within VCDS? Has anyone encountered a problem similar to what I have described in the past? Any suggestions about what path of influence to follow for fault isolation?

Michael

Michael,

I would be looking at the following measuring values in the the BCM (address 09 -- used to be called the CECM):

671,Tailgate condition - Rear lid remote release button,TT,
; not activated
; not coded/not installed
; operated
672,Tailgate condition - Release button in rear lid handle,TT,
; Coupling trunk lid with rear window
; not activated
; not coded/not installed
; operated
673,Tailgate condition - Main notch contact of rotary latch,TT,
; closed
; Open
674,Tailgate condition - Pre-engagement contact for rotary latch,TT,
; closed
; not coded/not installed
; Open
675,Tailgate condition - Status of rear lid lock,TT,
; Door lock: safe
; Implausible
; No communication
; not coded/not installed
; Signal from door lock: engaged
; Signal from door lock: released
676,Tailgate condition - Release,TT,
; Enabled
; not coded/not installed
; not enabled
677,Tailgate condition - Activation using rear lid unlocking button,TT,
; not coded/not installed
; OFF
; On

-Uwe-

Hi Uwe:

Thanks for the precise guidance, and thanks also for the very fast reply.

Wow - MVBs with numbers like 671 through 677 - that is downright scary. I wonder if Ross-Tech could perhaps gain a big advantage over competitors (most especially a big advantage over the VW dealership diagnostic systems) by incorporating a 'search for text string' feature into the MVB display? In other words, think of how much time it would save if I could open up controller 09 on a Golf or Jetta 7, go to MVB display, press a button called SEARCH, type in the criteria 'tailgate', then have all the MVBs with the word 'tailgate' in their label appear, with all the other MVBs filtered out? Jeepers, if you think about how much diagnostic time that could save a technician, that one feature alone would easily justify the $400 or $500 price of VCDS. The same concept (being able to search and filter by text string criteria) could, possibly, be implemented in the adaptation function as well - think about the 1,500+ adaptation fields in controller 09 of a 2015 Golf.

Michael

PanEuropean said:

The exterior trunk release operates intermittently, but predictably intermittently.

If the car has been used (woken up) within the past 2 minutes or so, and the car is subsequently locked, the trunk can be opened by pressing the exterior trunk release above the licence plate, as long as there is an authorized key within range. But, if the car has been locked for more than about 2 minutes, there is no response after pressing the exterior trunk release with an authorized key nearby. It is necessary to repeatedly press the exterior trunk release (generally about 7 to 10 attempts) before the trunk will unlock.

Click to expand...

That sounds like more of a problem awakening from deep-sleep than a problem with wiring to that switch. If the wiring to that switch were at fault, it would misbehave intermittently at all times, not just when the car has been asleep for a while.

Check to see if the selling dealer failed to take the car out of Transport Mode during PDI, like you experienced with your new Golf not long ago.

Jason

PanEuropean said:

I wonder if Ross-Tech could perhaps gain a big advantage over competitors (most especially a big advantage over the VW dealership diagnostic systems) by incorporating a 'search for text string' feature into the MVB display? In other words, think of how much time it would save if I could open up controller 09 on a Golf or Jetta 7, go to MVB display, press a button called SEARCH, type in the criteria 'tailgate', then have all the MVBs with the word 'tailgate' in their label appear, with all the other MVBs filtered out?

Click to expand...

Yep, that's been on our to-do list for VCDS "classic" for a while. VCDS-Mobile actually has that (or something darn close to it).

-Uwe-

jyoung8607 said:

Check to see if the selling dealer failed to take the car out of Transport Mode during PDI...

Click to expand...

I bet that is exactly the cause of the problem. I'll let you know how it turns out. Thanks Jason!

Michael