I have a problem with the service engine light coming on in my 99 z28. The code is "secondary air injection solenoid valve circuit malfunction bank A. I've checked the ball valve in bank A, and replaced the secondary air injection solenoid valve and the light and the code keeps coming back. does anyone have any suggestions as to what else I can check?

 

Is there power going to the solenoid?
PCM supplies power to both wires, aka, battery voltage will be read if referenced to ground.
When PCM commands solenoid to open, one side goes low, to maybe 0.5 volts.
If the PCM driver is broken, meaning one wire will never go low, solenoid never opens.

Generally, one wire, black maybe, will always have battery power, controlled by an ign power on relay and fuse inline, could be a black wire.
The colored wire will be PCM controlled.
You could hook up an LED test lamp to inside the interior for watching to see if it ever comes on - wire LED across the solenoid connector.
Compare with bank B.