VCDS 48V MHEV

   #1  

hughdaniel

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Hi

I'm at the point of completing a purchase of VCDS but I need to know whether it has the capability to de-energise the 48V MHEV system on 2018 and up A6/7 Q7/8 vehicles? I have an out of warranty A7 sportback with a dead Belt Starter Generator to repair.

Kind Regards,
Hugh
 
   #2  

Uwe

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Hmm... Not sure what's involved there. It's not a question that's come up before on the 48V mild hybrids.

On the A3 e-tron and the "GTE" VW's with the same sort of 400V hybrid powertrain, physically de-energizing the 400V system is done by pulling a jumper-plug on a 12V circuit under the hood. That circuit has to have continuity for the contactor in the battery to close. The only thing the factory scan tool does is give you a bunch of warnings and perform some checks (with the aid of an high-voltage probe) to verify that the contactor is indeed open and the system is "safe".

-Uwe-
 
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hughdaniel

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Cheers for getting back to me Uwe,

The repair instructions read as follows.

2.2.3 Disconnecting and connecting battery
The 12 Volt system is supported by the 48 Volt system via
the voltage converter (48 V/12 V) -A7-.
As a result, the 12 Volt system is only de-energised when the 48 Volt system has previously been de-energised.

2.2.5 De-energising 48 Volt system
-Vehicle diagnostic tester is used to de-energise 48 Volt sys‐ tem.
Special tools and workshop equipment required: Vehicle diagnostic tester

De-energising the system
The 48 Volt system must be de-energised in Diagnosis mode of ⇒ Vehicle diagnostic tester and ONLY by this method.

– Connect vehicle diagnostic tester.
– Select 'Diagnosis' mode and start this mode.
– Select 'Special Functions' tab.
– Select '48 V Electrical system' folder.
– Select 'De-energisation of 48V electrical system' in folder.
– Start selected program and follow instructions on display of vehicle diagnostic tester.



Ive been wanting to get VCDS a while now and if it can do these functions I'll be buying it straight away!.

Hugh
 
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Uwe

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– Connect vehicle diagnostic tester.
– Select 'Diagnosis' mode and start this mode.
– Select 'Special Functions' tab.
– Select '48 V Electrical system' folder.
– Select 'De-energisation of 48V electrical system' in folder.
Start selected program and follow instructions on display of vehicle diagnostic tester.
Those instructions are very similar to the ones for the 400V "GTE" type drivetrains. In the last step, their tester runs through some kind of script. I'm confident that whatever the tester actually does in terms of reading or writing stuff to the car could be duplicated with VCDS, but I'm not aware that anyone has developed a procedure to do so. This is one of the problems with VAG's current approach to repair info: They bury way too much of it in scripts in their own tester.

-Uwe-
 
   #5  

hughdaniel

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Finally got around to getting this A7 back onto a ramp and fixed!

Ended up using ODIS to disable the 48v system, But my Autel and VCDS could both recode the new 48V starter generator and close the charging contact in the 48v lithium battery. Bit of drama as the coding from the old unit was corrupted but got there in the end!
 
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   #6  

Muro8667

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Finally got around to getting this A7 back onto a ramp and fixed!

Ended up using ODIS to disable the 48v system, But my Autel and VCDS could both recode the new 48V starter generator and close the charging contact in the 48v lithium battery. Bit of drama as the coding from the old unit was corrupted but got there in the end!
Hi

where did you got the Code for the alternator? I have VCDS only...Can you pls help me?

BR
Murat
 
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stefdds

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@Muro8667 , since you are a verified member, I would start your own thread in the appropriate section (note the "support" sections) with your question(s) and reference this post/thread as a reference.
 
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