Originally Posted by GUSTO14

Mike, not necessarily. If it IS the ground to the windshield wipers and since the wiper motor is mounted in fiberglass, it would need some other way to be grounded. Without the wiper motor being grounded it wouldn't necessarily cause a problem, other than prevent it from operating when the switch tries to feed it power normally. It could however feedback through the armature of the wiper motor to other components that also normally receive power from that circuit.

Needless to say the wipers will not work without a ground, so all it does is turn the wiper housing to a positive source from the battery. This is how I discovered the problem. While troubleshooting the wipers that were not working (after reinstalling my engine), the trouble lite would light up when it touched the wiper housing. Since this shouldn't happen, I knew the wiper was receiving 12 volts somehow and immediately thought it must be coming through the ground wire.

If this is/was the source of your drain, and you connect it to a ground on the engine, you may well discover that your wipers now work.

It is possible that with 12 volts connected to the wiper housing the power was backfeeding though the wiper motor causing a drain. The armature must be connected to a ground to work, so with 12 volts being fed to the wiper housing (via its' normal connection to ground), at the very least, power can backfeed through the armature and at least one of it's brushes to other circuits that normally receive power on that circuit.

I wouldn't recommend you do this now, but when the wire you removed from the starter positive lug was connected, testing the wiper housing with a trouble light connected to a good ground, would have revealed the housing was 'hot' with 12 volts.

Good luck... GUSTO