IIRC the blower controller gets a signal through a yellow wire from the PBU. There's a junction block just outside the blower case beside the brake booster. Anyway, check the voltage at the small wire/s feeding the controller. Skip solid brown wires and the big wires that power the blower motor. If you see anything like a 6-7V signal from the PBU when the PBU is set to OFF, the PBU is fried.

At any rate, it's poor practice to troubleshoot an automotive electrical system by randomly applying +12V and ground. That's okay for basic consuming devices, but switches and sensors usually feed sensitive electronics. Hopefully a fried PBU is the worst of it.

Sixto
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