2016 Passat Electrical Firestorm

[DV52]

Forgive my newbieness,but what is the 01 Module, the ECM/ECU?

No need to seek forgiveness - we were ALL new-bees at some stage in our learning journey in the dark arts of diagnostic devices like OBD11!!

There are a gazillion different TLAs (Three-Letter Acronyms) used in the language of vehicle technology - so its not unlike every other field of endeavor in the modern age!! The TLAs below might help in your understanding of these responses

• TCM = Transmission control module
• ECM = Engine Control Module
• ECU = Engine Control Unit
• PCM = Powertrain Control Module

So, ECM and ECU have ostensibly the same meaning. TCM is sometimes called the "Mechatronic Unit/Module" on dual clutch gearboxes. PCM is mentioned in the U010000 error (Lost Communication with ECM/PCM). I suspect "Powertrain" when used in the context of the error message refers to the combination of ECM and TCM. However, on a MQB platform car like this Passat, separate modules are used to control the engine and the transmission - and the term "Powertrain" has a particular meaning; it relates to the "Powertrain CAN bus" which looks like this:

Now that think of it, this issue did first arise after I did a “disable safety disclaimer” code change (via an obd11 app) which I have since reversed. I could not imagine how this could have been the cause however being such a basic on/off code change.

Hmm.......... OK, you are clearly a "One-Click-App" user then - that's not good! I NEVER use OCA's because they make changes to the car's coding that are NOT disclosed. This is not a problem if the OCA works - but when the loose stools in the moist brown stuff collide with the proverbial fan blades, these secret coding changes can be a disaster to unwind. If you doubt that OCAs do not sometimes work - look on the OBD11 forum for many examples!

So, my suggestion is that you view OCAs like throwing dice (they are a gamble with REAL consequential risks); lots of times you win - but some times you lose! And the more OCAs that you use - the greater will be the risk of disaster!!

Again, I NEVER use OCA's and I urge that you consider making ALL coding changes with OBD11 manually!

Don

[Polska111]

No need for apology - we were ALL new-bees at some stage in our diagnostic device learning journey!!

There are a gazillion different TLAs (Three-Letter Acronyms) used in the language of vehicle technology - so its not unlike every other field of endeavor in the modern age!! The TLAs below might help in your understanding of these responses

• TCM = Transmission control module
• ECM = Engine Control Module
• ECU = Engine Control Unit
• PCM = Powertrain Control Module

So, ECM and ECU have ostensibly the same meaning. TCM is sometimes called the "Mechatronic Unit/Module" on dual clutch gearboxes. PCM is mentioned in the U010000 error (Lost Communication with ECM/PCM). I suspect "Powertrain" when used in the context of the error message refers to the combination of ECM and TCM. However, on a MQB platform car like this Passat, separate modules are used to control the engine and the transmission - and the term "Powertrain" has a particular meaning; it relates to the "Powertrain CAN bus" which looks like this:





Hmm.......... OK, you are clearly a "One-Click-App" user then - that's not good! I NEVER use OCA's because they make changes to the car's coding that are NOT disclosed. This is not a problem if the OCA works - but when the loose stools in the moist brown stuff collide with the proverbial fan blades, these secret coding changes can be a disaster to unwind. If you doubt that OCAs do not sometimes work - look on the OBD11 forum for many examples!

So, my suggestion is that you view OCAs like throwing dice (they are a gamble with REAL consequential risks); lots of times you win - but some times you lose! Again, I NEVER use OCA's and I urge that you make ALL coding changes with OBD11 manually!

Don

Thank you for the breakdown!

Yes I have used OCAs before mainly out of convenience.

Is there any way to view what the processes within the OCA is so that you can reverse engineer/wind back what was done by it, without relying on the OCA itself to just reverse the state back?

Alternatively, is there a way to do an ecu factory reset, or preferably, reverse it back to what it would have been at the time exiting the factory?

Im not sure if there is a repository for default module settings based on VIN.

Wishful thinking perhaps.


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[DV52]

Is there any way to view what the processes within the OCA is so that you can reverse engineer/wind back what was done by it, without relying on the OCA itself to just reverse the state back?

As I said in my previous reply "OCA's .........make changes to the car's coding that are NOT disclosed". So the answer to your specific question about OCAs is a resounding NO!

However, this ain't the case if you make coding changes manually. To understand the difference with manual coding - you first need to understand what happens inside the car's module when you make coding changes. Regardless of whether you use OCAs, or manual coding - the change process inside the module is that the new-value is written over the old -value and the old-value is lost!

However, good diagnostic devices (like OBD11) use separate software to "catch" the old-value before it is lost by the module -but this happens for code changes ONLY if they are done manually. OBD11 saves a detailed record of every manual process that you undertake with the device. This includes stuff like SCANs, manual coding changes (to both adaptation channels and long-code strings), Basic settings, Backups, Faults and lots, lots more. But NOT OCAs!

The database is stored against your OBD11 account and it can be accessed anytime without connecting to the dongle by selecting History. I suggest that you look on your OBD11 account for the History database (if you use the iOS version software, Select Garage on the Home screen)

Alternatively, is there a way to do an ecu factory reset, or preferably, reverse it back to what it would have been at the time exiting the factory?

I'm not sure if there is a repository for default module settings based on VIN.

Wishful thinking perhaps.

Yes, this car does indeed have a default "repository" and yes it is VIN based! ALL MQB platform cars that roll-off the factory production line have a complete copy of each module's factory programming stored (by VIN) on the central servers on the VAG mother-ship. This database is called FAZIT - which is the German acronym for "Vehicle information and central identification tool".

To access the database, a remote connection is required to FAZIT - but this is a restricted facility that's only available to dealers and other authorized agents that have registered GeKo accounts. This is a fee-for-service facility that's completely outside the reach of any third party diagnostic device like OBD11!