ISC - Confused after testing

[steve]

Have you seen the ISC page from the 3s guys. It have more information about the inner workings.

http://www.stealth316.com/2-isc-iac.htm

Steve

 

[Boothman]

Thanks for the link.

I found some information about cleaning ths ISC. I already opened the ISC a few days ago and chekked this out. But mine ist pretty clean anl looks like new (so there's nothing to clean).

Daoes somebody have an idea, why the resistance is OK, but the pin doesen't move? If the ISC tries to move, it vibrates a bit, but nothing else...

Greetings,
Boothman

 

[steve]

If the ECU isn't driving the coils correctly the ISC isn't going to move.
About half of the ECUs I fix have damage to the ISC trace running under C106 from it leaking.
If you had a bad ISC before with shorted coils the drivers on the ECU could be bad.

Steve

 

[Boothman]

I don't think that my ECU is damaged.
I've also tested the ICS with a 12V Battery according to the manual test procedure. There was only a vibration, but the pin didn't move in or out...

Any idea?

Greetings,
Boothman

 

[steve]

I've also tested the ICS with a 12V Battery according to the manual test procedure. There was only a vibration, but the pin didn't move in or out...

The ISC is a stepper motor. The manual test doesn't cause the pintle to more more than a step. Like I said if you don't power the coils in the right order the pintel doesn't really move.

There isn't much involved here. You have the ISC, the wiring, and the ECU.

Steve

 

[AL92]

My one reads 28 on all coils and the other one that looks brand new but might be aftermarket is reading 38 on all coils.
The one reading 28 looks like oem.the other one is black and looks aftermarket.Is 38 anthing to be concerned about they all read 38 on the one.

I have been having big time idle surging on my 91 turbo. I just yesterday got really angry at the thing and started to do something about it.I relaced the tb shaft seals and
have my tb off to welder to the no fiav tig mod to it. I had my tb on my 97 done at FFWD and he did same stuff but ported it ,tigged the fiav hole and changed tb seals.

I haven't thrown the tb back on the car and do have two actually three isc motors not counting one one on my 2g which assume are interchangeable 1g and 2g?

I looked at my ecu,the car had a badly burnt one and replaced it with another ecu that looked fine but didn't check under the board to see if there was any trace damage. I didn't have the car running at all with the old ecu so not sure if the surging was there before.
My suring is very fast surging ,starts right after the car starts and warms up a bit.It cycles very quickly from like 1000 to 1500 right now or so.

So guess will check the ecu if can't get the idle to work right.Buddy is electrical engineer so no big deal there if needs some trace repair as long as its not crazy damage.

So can the isc still work ok at 38 ohms instead of 33 and if its bad why do they all read 38 on that one.I think my meter is working right ,its new and wasn't cheap and the other isc I tested did read 28 on all four coils.

Also my haynes manual for testing says to use a 6 volt only battery not a 12 as the 12 will damage or destroy the isc!!! You can plug it into car it says and see if it moves also.
I haven't tried that yet.

 

[97GST_Spydr]

I had IDLE surge from 900- 1500 RPM.


First, check your "BISS" screw. -Base Idle set screw

Make sure the screw is not backed out,
IE: turning easy or (loose). watch your Tachometer, it should decrease RPMs.


...then to check your Idle Speed control (servo motor);

the ISC or IAC connectors are;

(TOP) -where 6 wire connector tab lock is)


! !
-------
1 2 3

4 5 6
-------


Check motor...Use a 6 volt Lantern Battery ($3-$4)
---to test motor (it will move or vibrate),

---to test; connect battery (+) and (-) to connectors 2-5 and 3-6.

.....then check the coils;

> the ohms test are 28-32 ohms on the connectors,

> I tested connectors;

1-2 then 2-3 then 4-5 then 5-6.


NOTE: always CHECK your "BISS" screw first, (its the Idle adjustment screw on top)

>>> I made this mistake, and wasted alotta time checking my ISC (stepper motor) first,
then wasted time and $ buying an ISC at a junkyard,
---when all that was wrong with the cars IDLE was a loose BISS screw ----(argh!)

Good Luck,

 

[feardafish]

My one reads 28 on all coils and the other one that looks brand new but might be aftermarket is reading 38 on all coils.
The one reading 28 looks like oem.the other one is black and looks aftermarket.Is 38 anthing to be concerned about they all read 38 on the one.

So can the isc still work ok at 38 ohms instead of 33 and if its bad why do they all read 38 on that one.I think my meter is working right ,its new and wasn't cheap and the other isc I tested did read 28 on all four coils.

According to that 3s website, the newer IAC motors will test bout 40 ohms. Wouldnt be concerned bout that.

 

[BobG]

Yes, I am POSITIVE that's the right resistance for the new ISC. The one I put in my 1G 92 Laser yesterday reads right in that range for all four windings.

If you're not familar with stepper motors, go visit Stepper motor - Wikipedia, the free encyclopedia to learn how they work. NOT the DC brush motors you learned about in 5th grade science class. The ISC is in the unipolar stepper motor class of devices.

Since it's known good but does not move under ECU control, yes I agree with the previous post. Problem has almost got to be in the brain box or harness. When mine failed, it DID smoke the ECU motor driver IC also.

Got mine from, of all places, Checker Auto Parts. It's a GENUINE MITSUBISHI E9T15292C but they sell it under their Duralast line as part number AC311 for $80. Just ask for their p/n AC311 = The kid behind the counter will tell you that a 92 Laser doesn't have a ISC!