Need help setting up MS3Pro with Stepper Motor

[280GE 1JZ]

Hi All,

I need help to run Stepper Motor with MS3pro. The engine is 1JZ-Gte vvti with ms3pro firmware 1.3.1. I have replaced the stepper driver 4 times now because its always broken after driving a while. I also have tried several wiring and the result always the same. It configured as open-loop warmup moving only. Full pintle travel is 148steps.

1. First Wiring as per original engine wiring and ms3pro manual.
S1= IAC1A
S3= IAC1B
S2= IAC2A
S4= IAC2B
B1+B2 = switched +12v
This give very fast respons, But everytime the idle motor moves ms3pro read a voltage rise up to 14+V when the car only have 13,2V. I talked about this to Matt Cramer
and he suggested installing diodes from each stepper output to switched 12v.

2. Second Wiring same as above but added diodes from each stepper output switched 12v. The respons is much slower, and less voltage rise.

3. This Time I removed the switched 12v from B1 and B2. This setup gives even slower respons. I can go 1500steps from fully closed to fully open. But after changing "time
step size" to 5ms the respons is back to normal and it have 148steps from fully closed to fully open.

all this setup ended up with a damaged stepper driver. So I'm ordering another batch of stepper driver, but before I go any further can anyone help me? Thanks all.

Regards,
Doddy

[jsmcortina]

I have some ideas on this and will discuss with Matt on Monday.

James

[billr]

Is the stepper driver IC different in a Pro than the MS3?

[racingmini_mtl]

The second picture is not consistent with the first one because S2 and B2 seem to be swapped in the second picture. Have you measured the resistance between the different pins?

Jean

[280GE 1JZ]

Yes, the stepper motor driver is different from ms3. Ms3pro use A4970GLBT. And I think in the second picture s2 and b2 is missplaced. I measured mine around 26-28 ohms.

Doddy

[jsmcortina]

Yes, the stepper motor driver is different from ms3. Ms3pro use A4970GLBT. And I think in the second picture s2 and b2 is missplaced. I measured mine around 26-28 ohms.

Doddy

The A4970GLBT is the manufacturers new replacement part. They should be identical.

James

[Matt Cramer]

Please make sure the MS3-Pro logic ground is connected to the same point as the power grounds. I've seen failing to connect this cause problems with the stepper output.

[280GE 1JZ]

Hi Matt,

Yes, all the power ground and logic ground goes to battery negative terminal. Each using 20awg wire. Any info from James? He said he have some ideas about this and going to talk to you. Thanks.
Doddy

[jsmcortina]

Hi Matt,

Yes, all the power ground and logic ground goes to battery negative terminal. Each using 20awg wire. Any info from James? He said he have some ideas about this and going to talk to you. Thanks.
Doddy

Have you tried grounding to the engine block as recommended ?

James

[280GE 1JZ]

Hi James,

Whats mean by grounding to engine block? Moving the power and logic ground to engine block instead of battery? Thanks.

Doddy

[Matt Cramer]

Exactly.

[280GE 1JZ]

Ok. I'll try this tomorow. Thanks.

Doddy

[280GE 1JZ]

Hi Matt,

I found the problem. Its the alternator diodes. It kind of sorted while i'm driving and drained my battery instantly. I have to buy a new battery too after replacing the alternator. with new alternator my dashboard temp meter and fuel indicator are no longer dancing around. Steady as it would in normal car. And a few days ago the replacement stepper driver arrived and installed. And its been working flawlessly. Thanks all for the support.

Regards,
Doddy

PS: I'll post again if the stepper driver fail again. Hehe