More Electronic parking brake, J540 error

[GBDamo]

Hi All, new here so please be gentle.


Recently got the Passat back on the road after about six months on bricks due to an ERG and O2 sensor fault and lack of funds to repair.

During this time the battery died, dropped to <6V and would not re-charge so got a new one only to find the bonnet catch had seized. So, stripped, cleaned and re-greased the catch and took it in to resolve the O2/ERG issue and get an MOT.

Collected car from garage and all was well until about five miles then the ABS and Traction Control warning lights came on, so I went straight back to the garage. He plugged it in and it came up with Brake Control Module J540 fault which he then cleared.

I set off again and got most the way home before the same thing happened, this time I parked it on the drive and when I returned the fault had cleared it's self. But now, after paying a bit more attention, I've noticed that it seems to come on when the car reaches 50-60mph and then clears when the car is parked for a while. I can drive round all day in town with no issue but the minute I go on a an A road/motorway the warning lights come on.

I've been told it will require a new J540, and re-coding, which may have been fried due to the low voltage issues and while I can accept this I just wanted to make sure this is the issue and not the beginning of a long an convoluted wild goose chase.

Any thoughts would be very welcome.

Cheers

Damoin

[RichardSEL]

The Electronic Parking Brake control module should first be re-initialised in VCDS. If it will accept the basic settings:
http://wiki.ross-tech.com/wiki/index.php/VW_Passat_(3C)_Parking_Brake
then the module shouldn't need changing.

You don't say what year Passat you've got. There are some later modules that are more sensitive to fault conditions and failure than others. They are the 3c0 "J" series that need changing to 3aa 907 801 J. And a different coding string: from 0000057 to 0021057

This might be an internet olde wife's tale or it might actually work. I've never done it. But it could help you if you're out and about and you get the fault again:
Forced Reset of EPB Control Module
• Switch ignition OFF.
• Disconnect battery.
• Wait at least 10 seconds and reconnect battery.
• Switch ignition ON.
• While pressing brake pedal, operate electronic parking brake button twice.

[niall campbell]

I would check the voltage of the alternator

If the alternator is not charging the battery, then the ECU thinks the brakes wont work.

This might be why your battery died a death.

The cars used to check the battery on starting the car, with lots of faults due to the ECU not waiting for the battery to get a charge from the alternator

Think my A6 was showing brake problems after exactly 7 minutes, until I changed the alternator

It might be ok, but its free to check

[GBDamo]

The Electronic Parking Brake control module should first be re-initialised in VCDS. If it will accept the basic settings:
http://wiki.ross-tech.com/wiki/index.php/VW_Passat_(3C)_Parking_Brake
then the module shouldn't need changing.

You don't say what year Passat you've got. There are some later modules that are more sensitive to fault conditions and failure than others. They are the 3c0 "J" series that need changing to 3aa 907 801 J. And a different coding string: from 0000057 to 0021057

This might be an internet olde wife's tale or it might actually work. I've never done it. But it could help you if you're out and about and you get the fault again:
Forced Reset of EPB Control Module
• Switch ignition OFF.
• Disconnect battery.
• Wait at least 10 seconds and reconnect battery.
• Switch ignition ON.
• While pressing brake pedal, operate electronic parking brake button twice.

thanks for the reply, it's an 08. I will try the witchcraft you suggest before I go any further.

[GBDamo]

Thanks for the reply, i'll keep this in mind if above witchcraft fails.