Stepper IAC wiring - pin 29 missing

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Re: Stepper IAC wiring - pin 29 missing

Postby Madkaw » Thu Nov 16, 2017 8:59 am

well I pulled the ecu since I obviously missed something. I admit to not reading carefully , and found Q16 -finally-and yes it is jumpered . I took a pic but for some reason I am having trouble uploading-(board attachment has been reached?)
So I just unsoldered it.
Last edited by Madkaw on Thu Nov 16, 2017 10:12 am, edited 1 time in total.
Steve
1971 Datsun 240z 2.4 L6 1975 EFI intake with 1.8 audi Bosch injectors
MS3x 3.57 Ignition LS1 coils running wasted COP, CAS
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Re: Stepper IAC wiring - pin 29 missing

Postby Madkaw » Thu Nov 16, 2017 9:46 am

Well reassembled everything and still the same results on the voltage tests and running tests. So have I disconnected something I shouldn't have ?
Steve
1971 Datsun 240z 2.4 L6 1975 EFI intake with 1.8 audi Bosch injectors
MS3x 3.57 Ignition LS1 coils running wasted COP, CAS
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Re: Stepper IAC wiring - pin 29 missing

Postby billr » Thu Nov 16, 2017 11:02 am

I'm short on time, but have a quick question: did you send several commands to the IAC and see all but pin 36 toggle from 0-12V; is pin 36 the only one that is "stuck" at 12V?
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Re: Stepper IAC wiring - pin 29 missing

Postby Madkaw » Thu Nov 16, 2017 11:54 am

Okay-so just now tested and have
1a-0v
1b-12
2a-0v
36-12v
and to be sure -this is testing wires UNATTACHED from the stepper and using separate ground. Changing commands changed nothing.
Checking voltages while wired to stepper I got
1a-10.3v
1b-10.3v
2a-5.5v
36-5.5v
Changing commands changed nothing
Steve
1971 Datsun 240z 2.4 L6 1975 EFI intake with 1.8 audi Bosch injectors
MS3x 3.57 Ignition LS1 coils running wasted COP, CAS
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Re: Stepper IAC wiring - pin 29 missing

Postby jsmcortina » Thu Nov 16, 2017 12:19 pm

The best way to test is to turn off Idle Control and use the output test mode to manually turn IAC1 on/off and IAC2 on/off. That way you can be sure what the outputs should be doing without short "steps" confusing you.

James
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Re: Stepper IAC wiring - pin 29 missing

Postby Madkaw » Thu Nov 16, 2017 12:33 pm

Turn off idle control? You mean select "none" under Idle control? Then you wouldn't have a test mode available .
Steve
1971 Datsun 240z 2.4 L6 1975 EFI intake with 1.8 audi Bosch injectors
MS3x 3.57 Ignition LS1 coils running wasted COP, CAS
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Re: Stepper IAC wiring - pin 29 missing

Postby jsmcortina » Thu Nov 16, 2017 1:12 pm

Madkaw wrote:Turn off idle control? You mean select "none" under Idle control? Then you wouldn't have a test mode available .

Yes you would.

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Re: Stepper IAC wiring - pin 29 missing

Postby Madkaw » Thu Nov 16, 2017 9:24 pm

Let me make sure I am understanding this.
To turn off idle control I need to select none as far as idle valve. Then your asking me to go to test modes and test the outputs using the idle valve output test( which is not available if I have selected none for idle valve)

I'm confused.
Steve
1971 Datsun 240z 2.4 L6 1975 EFI intake with 1.8 audi Bosch injectors
MS3x 3.57 Ignition LS1 coils running wasted COP, CAS
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Re: Stepper IAC wiring - pin 29 missing

Postby Madkaw » Thu Nov 16, 2017 9:32 pm

Okay- I searched and figured out what to do to test outputs. I'll let you know
Steve
1971 Datsun 240z 2.4 L6 1975 EFI intake with 1.8 audi Bosch injectors
MS3x 3.57 Ignition LS1 coils running wasted COP, CAS
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Re: Stepper IAC wiring - pin 29 missing

Postby Madkaw » Fri Nov 17, 2017 8:59 am

So I used the I/O output tests and powered up IAC1 and IAC2 and took voltage readings. I used the chassis as ground. I checked battery voltage and it was low at 11.97v's-time to charge it up I guess.
IAC 1


1A-11v
1B-0v
2A(36 pin)-0v
2B-11v

IAC2

1A-0v
1B-11v
2A-0v
2B-0v
Steve
1971 Datsun 240z 2.4 L6 1975 EFI intake with 1.8 audi Bosch injectors
MS3x 3.57 Ignition LS1 coils running wasted COP, CAS
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Re: Stepper IAC wiring - pin 29 missing

Postby jsmcortina » Fri Nov 17, 2017 9:04 am

Seems that your 2A output is either not connected or broken.

Try repeating the test on that output with your voltmeter between battery +ve and 2A.

James
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Re: Stepper IAC wiring - pin 29 missing

Postby billr » Fri Nov 17, 2017 9:18 am

Again, I can't use the pictures posted to check how the mainboard was modified to route 2a out through pin 36 instead of pin 29. Has anybody else verified that all looks OK there?

OP, are you sure Q16 has been disconnected from pin 36?
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Re: Stepper IAC wiring - pin 29 missing

Postby Madkaw » Fri Nov 17, 2017 9:24 am

billr wrote:Again, I can't use the pictures posted to check how the mainboard was modified to route 2a out through pin 36 instead of pin 29. Has anybody else verified that all looks OK there?

OP, are you sure Q16 has been disconnected from pin 36?


There was no modification done to pin36 to route instead of 29. I took literally that I could JUST USE pin 36 as I posted earlier. I made sure there was no jumper attached to Q16 -so is this my issue?
Steve
1971 Datsun 240z 2.4 L6 1975 EFI intake with 1.8 audi Bosch injectors
MS3x 3.57 Ignition LS1 coils running wasted COP, CAS
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Re: Stepper IAC wiring - pin 29 missing

Postby jsmcortina » Fri Nov 17, 2017 9:31 am

Madkaw wrote:
billr wrote:Again, I can't use the pictures posted to check how the mainboard was modified to route 2a out through pin 36 instead of pin 29. Has anybody else verified that all looks OK there?

OP, are you sure Q16 has been disconnected from pin 36?


There was no modification done to pin36 to route instead of 29. I took literally that I could JUST USE pin 36 as I posted earlier. I made sure there was no jumper attached to Q16 -so is this my issue?

Well yes, you haven't connected it to anything.
Inside the case you need pin36 to connect to IAC2A.

James
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Re: Stepper IAC wiring - pin 29 missing

Postby Madkaw » Fri Nov 17, 2017 9:36 am

billr wrote:Use pin 36 that was reserved for the single-coil ignition driver.


I guess I took this too literal-
Steve
1971 Datsun 240z 2.4 L6 1975 EFI intake with 1.8 audi Bosch injectors
MS3x 3.57 Ignition LS1 coils running wasted COP, CAS
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Re: Stepper IAC wiring - pin 29 missing

Postby Madkaw » Fri Nov 17, 2017 9:55 am

Okay-so I'm on the same page now as far as what to do, but now its about HOW to do.

So how to connect pin 36 to 2A? I see 2a has a jumper wire on the CB -do I disconnect the other end and jumper it over to q16 ?
Steve
1971 Datsun 240z 2.4 L6 1975 EFI intake with 1.8 audi Bosch injectors
MS3x 3.57 Ignition LS1 coils running wasted COP, CAS
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Re: Stepper IAC wiring - pin 29 missing

Postby jsmcortina » Fri Nov 17, 2017 11:15 am

See here:
http://www.msextra.com/doc/pdf/html/MS3XV357_Hardware-1.4.pdf/MS3XV357_Hardware-1.4.html
There's an image of the reverse side of the board with the jumper wires from the processor to the connector.
At the connector end (left), remove the wire that was going to pin 29 (2A) and reconnect it so the signal goes out through pin 36 instead. You may need to extend it.

James
I can supply, repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: viewtopic.php?f=104&t=34277
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Re: Stepper IAC wiring - pin 29 missing

Postby Madkaw » Fri Nov 17, 2017 4:48 pm

James,
I see 2a coming from the processor. I understand I need to un solder from connector end. I need to reconnect to pin 36. from I can tell , 36 ends up at IBT OUT ( pad q16) , which I was told to make sure there was no jumper there. There was and I disconnected it. So can I just go from processor to q16 - which is connected to pin 36 ?
Steve
1971 Datsun 240z 2.4 L6 1975 EFI intake with 1.8 audi Bosch injectors
MS3x 3.57 Ignition LS1 coils running wasted COP, CAS
Madkaw
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Re: Stepper IAC wiring - pin 29 missing

Postby jsmcortina » Fri Nov 17, 2017 5:36 pm

Madkaw wrote:James,
I see 2a coming from the processor. I understand I need to un solder from connector end. I need to reconnect to pin 36. from I can tell , 36 ends up at IBT OUT ( pad q16) , which I was told to make sure there was no jumper there. There was and I disconnected it. So can I just go from processor to q16 - which is connected to pin 36 ?

Yes, connect the processor wire to IGBT OUT. Check that has continuity with pin 36 first.

James
I can supply, repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: viewtopic.php?f=104&t=34277
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Re: Stepper IAC wiring - pin 29 missing

Postby billr » Fri Nov 17, 2017 6:39 pm

Sorry if I'm confusing things here, but I don't want the OP to get led astray.

James. what you are saying doesn't seem to correlate to the schematic to me.

As I see it, "IGBTout" does not connect to pin 36. Pin 36 connects to pad "IGN" and a jumper is needed between "IGBTout" and "IGN" to use Q16 as a spark coil driver via pin 36. That jumper, the one from "IGBTout" and "IGN" is the one I think should be removed, if it is there. The processor pin for IAC 2a should be connected to the "IGN" pad and Q16 will be out of the IAC/pin 36 circuit for sure.
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