MSefi.com read only forum (Jan.15,2018)

I am having a problem getting the stepper motor to work correctly on my megasquirt 2 V2.2 board. The stepper motor appears to be a bi-polar jeep/dodge type with 4 pins. I bought a new one (so I have two) and they have the same problem, so I have eliminated the motor as a problem. I have checked the JP1 hole 6, and I am getting 12V to the pin. No obvious overheating or damage to any of the MS2 hardware.

The problem is, the stepper motor won't move. It wobbles a little bit when it is supposed to move when I cycle the ignition on and off. I have expirimented with the connections enough to be sure that the problem is not with the the "coil to pin" order. I have experimented with the time step size up to 25ms with no change. When tunerstudio is set to "IAC always on" I am only getting 7ish volts to 2 of the leads, and ground to the other 2. I also can hear a very high pitched, higher than the step size frequency, hum in the motor, as if there is some PWM noise in the circuit. Tunerstudio AIC position gauge shows that the stepper should be working.

My question is... Has anyone had this happen, and what was the solution? Is there some setting that I am missing that would cause this? Is my MS2 chip fried?

Thanks for any help.

My first thought is that one of the coils is wired backwards.

I quadruple checked it, and tried every order, and the order isnt the problem. I read somewhere that the stepper driver is protected for over-current by pwm when the current draw is too much. This is what it kinda sounds like its doing, even though the motor tests at 50 ohms. (the resistors on the chip are the jumpers labled "000", not "1R0" as shown in the megamanual)

I am starting to believe I have a firmware problem. I had major trouble getting the firmware loaded, and now, besides the stepper motor problem, the fuel pump never turns off. Without the motor running, the fuel pump just keeps running. Last night I tried to reload the firmware, but the jumper has no effect. The downloader says that the jumper needs to be installed... but it is installed. I am at a loss for what to do at this point. Should I send the MS2 card back to DIYAutoTune to have it checked and/or have the firmware deleted?

First, could you post a screen shot of the error message that you get when you load firmware? There may be some important clues in its exact wording. I'd like to first have you do some tests to narrow down that the problem is specifically the daughter card before arranging for a return.

Good news! after reading that someone else had this problem, I checked the bootloader pin, and it wasn't soldered at all. I soldered it in, and successfully loaded the firmware. This weekend I will get this back on the truck to see if it solved the IAC and FP issues!