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MSII daughtercard Idle control output stuck high
Posted: Mon Apr 04, 2011 1:05 pm
by Byrdhouse9
I have assembled my MSII and JimStim and was checking out the output signals on the bench. I used the TIP 120 transistor circuit described in the manual to work with my Ford PWM idle control valve. I connected the idle control valve to the IDLE output and (after setting up reasonable PW percentages and connecting the corrrect wire on the idle valve to 12 volts, etc) it started working, the idle valve responded when starting up and when making quick throttle changes. The next time I turned the system on, the idle valve stayed full-open like the output was stuck ON. Reading through the manual again, I see that I forgot to install the flyback diode across my idle valve. Thinking I probably fried the TIP 120, I disconnected it from the circuit and find that it is dead. But now I find the IDLE output on the MS II daughtercard (pin 34) is stuck at 5 volts. Have I fried the daughtercard or is there a setting in the software that could force this pin always high? If this output is fried, is there a way to send the IDLE signal out of another (spare) port, or am I stuck with buying a new card?
V3 mainboard, ECU is MSII Rev 2.891
Re: MSII daughtercard Idle control output stuck high
Posted: Mon Apr 04, 2011 5:52 pm
by Byrdhouse9
Reading over the question I posted earlier today, and have a correction. I was turning the Coolant temp pot on the JimStim and seeing/hearing the idle air control valve change position until it stopped responding. Don't know why I typed "throttle".
Re: MSII daughtercard Idle control output stuck high
Posted: Tue Apr 05, 2011 4:14 am
by Matt Cramer
I'd like to check your settings - could you please post a copy of your MSQ file?
Re: MSII daughtercard Idle control output stuck high
Posted: Tue Apr 05, 2011 5:32 pm
by Byrdhouse9
Here is the MSQ file. (first time I have attached anything on the forum, hope it works)
megasquirt201104052106.msq
I procured a replacement for the TIP 102 and upon checking it, realized my old one was still good - I had not noticed that it is a Darlington and does not Ohm out like a regular transistor. So, I installed the proper diode across the idle valve and reconnected the collector and emitter of the transistor. Now I can touch the wire to the base of the transistor and the idle valve clicks full open, regardless of CLT setting. As you can see (I hope) in the MSQ file, I have it set up for a PWM idle valve and have the table set up so the valve should respond as I run the CLT up and and down. So, I did not blow the transistor but it still appears the output on MS2 pin 34 is stuck high.
Re: MSII daughtercard Idle control output stuck high
Posted: Wed Apr 06, 2011 4:24 am
by Matt Cramer
You've also got PM2 - FIDLE enabled as a spare output port. This keeps the system from using it as an IAC valve. Disable it as a spare output port to let it work as an IAC valve - with it enabled as both the IAC output and a spare output port, the MS2 doesn't know which it should be used for.
Re: MSII daughtercard Idle control output stuck high
Posted: Wed Apr 06, 2011 9:47 am
by Byrdhouse9
That fixed it, thank you, thank you, thank you. I guess the warning in the manual about not changing settings you do not understand is really important....