Re: code 634
The PCM has seen a voltage outside the normal range for the feedback from this switch. The switch is supplied with a 5volt reference voltage and switch is just a variable potentiometer. Don't muck around, throw a new switch on it, its part of the neutral start switch. Be VERY carefull when installing the new switch, the selector shaft will be rusty, you may have to destroy the old switch to get it off. Clean the shaft well before fitting new switch, as forcing it on will damage the internals of it.
Had LOTS of dramas with these......................