4L60E solenoids always on

[Bernard Fife]

Greg,

The MShift controller *always* starts in the mode you specify under 'Shift Factors/Auto Shift Mode' and this can only be sequential shift auto (1) or skip shift auto (2) for the more recent codes.

If the controller appears to start in manual mode, it can only be because one of the shift button circuits are grounded (the upshift button, in your case). I suspect you have an intermittent short, but one that is borderline and allowing variable states. If you haven't washed the board in 99% isopropyl alcohol, rinsed in in hot water and let is dry completely, than that's the first thing I would do.

To confirm that the grounding is the problem, pull the PT6/VR2 jumper at the 25x2 header on the PCB. This will disable the upshift button, and you should stay in auto on startup. Then I would measure the voltage on the PT6 side of the header (be very careful not to bridge to another header pin with the probe) - it should be very near 5 Volts.

If that is okay, then put the jumper back in place, and measure the voltage at jumper in R60 (in the VR2 circuit). It should be ~5 Volts with the upshift button not pressed, and under 1 Volt with the upshift button pressed. If it is always 1 Volt or less, then the circuit is always grounded, requesting an upshift. So you need to find out why.

The next thing I would try if it is always grounded, is remove the Ampseal connector, and with no power to the controller measure the resistance from the jumper at R60 to ground (use the middle pin of the voltage regulator - the relatively large black 3-pin component at the opposite end of the PCB from the Ampseal connector near the heat sink components). The resistance should be quite high. If it isn't, then there's a short on the board, and you should go over the building of that section of the board very carefully against the assembly instructions: http://www.msgpio.com/manuals/mshift/assembly.html

If you have a digital camera and can get a decent shot of that section of the board, we could have a look too.

Let us know what you find and we will go from there.

Lance.

[turbolambo]

Lance i am running MS extra 2.1.0 on the engine.