MicroSquirt.com read only forum (Jan.15,2018)

Posted: Wed Jul 12, 2006 1:26 pm Post subject: IAC Control

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Hi,

Just a bit of help fault finding a non functionate Stepper. The item below (apologies for crap picture, only mobile handy at the time) came off a Rover V8, not sure of make but has following markings:

704409
B1884

Basically it seems to be always fully retracted i.e it lets air into the manifold constantly.

I've fiddled with the start position is MS to no avail, coil A and coil B both measure 58 Ohms which would seem to be correct, connected to 25, 27 29, 31.

Have I missed something on building the MS board

Using MS II V3 Board with MT 2.25 code 2.36

Any help appreciated.
Thanks

Darren

Darren,

Check the 5 jumpers:

- (1A)JS0 to IAC1A,
- (1B)JS1 to IAC1B,
- (2A)JS2 to IAC2A,
- (2B)JS3 to IAC2B,
- S12C to JS9 (+12C).

Then make sure you have the external wiring right. If:

- The stepper motor does not work at all. In this case one of the coil windings has the wrong polarity. To correct this, switch the wires around on either of the coil windings to see if it helps (i.e., trade the connections of the two blue wires). If it doesn't help, switch those wires back and try switching the other winding's green wires.

- The stepper motor works in reverse, i.e., it retracts when it should extend, and vice-versa. Reverse the wires so that the wires originally connected to:

- Coil 1, lead A is now connected to Coil 2, lead B,
- Coil 1, lead B is now connected to Coil 2, lead A,
- Coil 2, lead A is now connected to Coil 1, lead B,
- Coil 2, lead B is now connected to Coil 1, lead A.

There is much more on this here: http://www.megamanual.com/ms2/IAC.htm

Lance.

will give that a try, cheers

Darren

checked all above so can only assume the stepper is at fault.

Thanks

Darren