Stepper Motor Diagnostic

[steelroe]

Guys I was going through all the fto related stuff I download when I first got my GPX.

Stumbled on a really interesting 4 page procedure for testing for faulty stepper. I have checked the link but it no longer works. I will get my missus to scan it and maybe if I email it to Cj he will do the honours of placing it on the site here somewhere, will save time in the future.

Until then it stated the following possible symptoms of a faulty stepper.

Low idle at cold_ no apparent choke (cutting out)
High Idle at warm- reving at 2000 plus RPM
Intermittent idle at other times (hunting).

[sinlessgunner]

I think I know this one...I may have it saved on my favourites on the computer at home (this is the gf's laptop) will check the link Friday.

Is it one with 3 or 4 small pics at the top of the page and a really detailed procedure for checking it broke up into Mechanical and electrical headings?

[steelroe]

Not sure, it has a description of how it works and than a mechanical and electrical testing method Post link and I will look at it. Original link i had ws http://homepage.ntlworld.com/jatcom/logos/stepper1.htm

[sinlessgunner]

Yeah definitly sounds like it alright. I was only at that link 2 weeks ago so I'm sure it's still active. Will post the link here tomorrow.

[GarLaf]

The test of the ISC motor is on page 163 of the workshop manual part 1 in pdf. section 13a-90. By special tool they mean multimeter

[CJ]

Rory has fowarded on a stepper motor diagnostic sheet that worth looking at if you're attempting to diagnose idle speed issues, check out the link below:

http://fto-ireland.com/downloads/stepper_diag.pdf

CJ

[sinlessgunner]

http://homepage.ntlworld.com/jaycom/fto ... tepper.htm

Heres the active link. Definitly works.

[CJ]

More stepper motor info from Rory:



CJ

[OllyH]

Hi- I found the Stepper Motor Diagnostic instructions- very helpful.

But after the check with the multi-meter, I am still not sure whether the ISCV (steppr motor) is really the problem. The resistances were all 40 Ohms, so on the high side but all the same and less than the 45 value it mentions. This is a Camskill replacement stepper, not the original- I already changed it about 5-6 years ago.

The last step in the instructions didn't work for me- I couldn't measure 12V on the centre pins of the wiring loom connector- I guess we're looking for 12V between either of those pins and chassis?

The problem I have is that sometimes, when cold and not driven for a few days, the car won't idle without foot on pedal. After a few minutes (as it warms up) it will then idle very low and hunts a bit. An ECU re-set sorts it out every time, after which it is perfect for a while. I am suspicious of the stepper even with the OK readings for resistance. If it's not the Stepper motor I guess it could be ECU? But which one to buy first?

Any help from someone with the right experience would be very useful.