Another IAC question. followup

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107merc
Experienced MS/Extra'er
Posts: 167
Joined: Fri Mar 28, 2014 10:35 am

Another IAC question. followup

Post by 107merc »

Have programmed IAC2 in Tuner Studio to control an electric fan. Power on is set to off and active value is on. Active condition is "coolant" threshold at 170
and hysterisis at 10. The fan turns on whenever the key is turned to "on" and stays on when the fuel pump is also on whatever the coolant temp. Does this mean
it is getting a signal from IAC2B and coming on?? do I have to remove the jumper to IAC2B?? I can test the IAC2 path in "test mode" by enabling it and it will turn the fan on.
Also, IAC1 is assigned as a tacho output to the stock speedo, do I have to remove IAC1B jumper for it to work correctly?? Any info appreciated.
Should add, we verified that pin 29 (IAC2A) of the cable connector goes to the winding of the fan relay and is not shorted with pin 31 (IAC2B). 2B is not connected to anything.
107merc
Experienced MS/Extra'er
Posts: 167
Joined: Fri Mar 28, 2014 10:35 am

Re: Another IAC question. followup

Post by 107merc »

As a reminder, my electric fan operates continuously. After testing with a logic probe, found out IAC2B starts "Hi until the coolant reaches 170 (as programmed) then goes "Lo"
which should turn on the Fan relay which has 12V on the other side of the winding. Turns out the MS "Hi" is about 10.5 volts while my battery voltage is 14.3V, more than enough
potential to operate the fan relay so it's on all the time. Think the fix will be to change to IAC2A which starts Lo then goes Hi at 170 and connect the other side of the winding to ground.
That way the winding is ground to ground below 170. Onward.

Need to proof read better. Should be 2A starts Lo. Had 2B
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