I have a GTA now!
Join Date: Oct 2011
I have advised by someone that knows these cars back to front that all you need to do is disconnect the battery, short the 2 battery wires together for a few seconds and then reconnect them to the battery SECURELY. That will get the car drivable again with the fault he's had, nothing more to it than calibrating the system after that.
To clarify, you are NOT shorting the battery (obviously), you are shorting the disconnected wires together.
hope that helps