ECU reset -- does disconnecting battery do it?

[craig-pd130]

Does disconnecting the battery reset the ECU? If so, how long should it be disconnected for?

Also, does resetting clear any fault codes? I haven't got any, just curious

thanks, Craig

 

[micky 32]

My ecu was disconnected for a couple of days as i was fitting the new hybrid turbo and clutch, not sure if it made a difference resseting though.

 

[Martyn]

I normally leave it disconnected for 10/15mins if I want to reset the ECU.

 

[muddyboots]

Craig

I did read on some Passat forum, of a problem (affecting Passats, obviously) where the selctive unlock and similar features stopped working. The relevant ECU (I think the central convenience module) seemed to get slightly screwed and not recognise some of the settings.

It seemed the cure was not only to disconnect the battery, but short the +ve and -ve leads battery together to discharge and reset the ECUs...

I keep meaning to do it on mine, as the selective unlocking doesn't work; with vag-com I can either set it so all doors unlock on first keyfob click, or that only the driver's door does (even with repeated clicks). Whichever setting I choose, the selective unlock will not work, which sounds like the symptoms I've read about. Haven't done it yet because I haven't got the radio code, keep meaning to go to a VW dealer and get it !

 

[RichardBW]

disconnecting a tdi/pd ECU will give you many faults when reconnected. You may put more in than you are taking away. Vagcom or similar is your best bet to clear all the faults completely.
The shorting of poss and neg batt terminals without voltage present was a BMW thing in order to discharge all the CU's completely. You could sometimes then get away without having to reset with a diag tool and this would clear all faults present. As far as I know this does not work on VAG cars until the latest CAN equipped versions?

 

[dingsdale]

I dont think it does reset it, on my non pd tdi 110 i had an airbag fault after taking the seats out (water leak...). Left the battery disconnected got a few hours and it didnt clear it, had to take it to the dealer who charged 4 quid