Upshift pressed always on. 4L80E

[marcars]

Hi,

On my 4L80E the upshift pressed light is always on. Is this normal? It does say it is in auto mode as soon as the controller fires up and stays there.
I also cannot find any schematics on how this cirquit is supposed to work, nor does it mention anything in the build manual. Am I overlooking something?

VSS cirquit is also pretty buggy. I've changed R45 from 300K to 150K to 100K and now on 47K. Still issues though. I've changed firmware to V 2.128 and now on 2.200 but still not very stable. Tried new sensor, no go. I measured the air gap between sensor and teeth and cam up with a value of 3mm, is this about right? It wat even 4mm with the old sensor. Seems a lot to me.

[Bernard Fife]

marcars,

Your upshift button is shorted to ground, either internally or in the wiring harness (or switch). The upshift circuit is VR2, and should be built as a digital input. The schematic is here: http://www.msgpio.com/manuals/vr.htm

Does the VSS input work properly on a stim?

Lance.

[marcars]

Lance,

I didn't populate VR2 as I don't use the up and downshift buttons (yet). Even if I pull the respective jumper, PT6 VR2 in this case, the situation stays the same. I've measured between PT6 and ground to check for a ground path and no, infinitive.

[Bernard Fife]

marcars,

You need to make sure that the circuit is pulled up to to a nominal 5 Volts (actually it needs to be over ~3.250 Volts, but 5 is better). Otherwise the processor thinks that output is grounded, and asking for a shift.

You can do this on the board with a few resistors and jumpers, but you cannot leave the circuit unpopulated. For the components you need to add, see step J. (sub-steps 1, 4, 5, and 6) here: http://www.msgpio.com/manuals/mshift/assembly.html.

Lance.

[marcars]

You're absolutely right. Works a charm now.

I had missed the general GPIO build part. Oops.

[Bernard Fife]

marcars,

Great, I'm glad it's working now!

Lance.