HeyMyCar,

I come to discover as their is no solenoid, and the smog pump is directly driven by the engine computer from active transistor like device-A true transistor has three pins. This device that drives the smog pump has a current sense leg that sends a logic-level condition to the microprocessor for current draw.

On my M104, the smog air pump driver transistor device was shorted. Someone on the web made some kind of little circuit to fool the computer with a operational amplifier (OP Amp as they are called). Cheap to build, to fool the check engine light...Interesting little circuit for us Californian's

Martin