TESTING STEPPER MOTOR WITH 12 V BATTERY

[feithv8s]

I have taken the stepper motor of my V8S out for testing as setting idle is quite bad.
The stepper motor has two coils, I think to give more or less valve opening.
Two coils with each two connections: resistance acc. the bible is OK.

My question: is it possible to see the stepper motor actually working when taken out and just connecting 2 pins to a 12V battery?
I tried, heard a very very soft click, but did not see the valve moving.

What signals are coming from the ECU?

Regards,
André Feith
V8S

[GreenV8S]

I've never tried testing a stepper motor off the car and I don't know the details of how this sort works, but usually with stepper motors they have several inputs which have to be pulsed in the right order to move the stepper motor one step.

[spend]

AFIK all you can check is the resistance across the A-D and BC coils (O-G/W and the other pair of wires).

Dave

[tahiti450]

IIRC, ages ago I did a basic function check on the stepper motor on my old MG Maestro EFI which I think is exactly the same. Remove it , leave it connected and just turn the ignition on / off and you should be able to see movement of the conical piston. At least confirms that the thing isn't dead.