Source of data on GM.GEAR PID

Hi guys,

I'm in the process of troubleshooting a shifting problem with my project car and knowing the source of data for the GM.GEAR PID will greatly assist with the troubleshooting process.

Summary:

Gen3 6.0 Volvo 240. Running cable throttle and flex sensor
4L80e, rebuilt by me
Whole car rewired by me
P59 PCM running 03150003 OS with 4L80e segment swap

I have mentioned 'by me' so people can safely assume I don't know what I'm doing and can also identify things I've likely screwed up.

The problem I'm having is with 2nd gear. It doesn't seem to exist for automatic upshift or automatic downshift, yet everything else in the transmission works nicely (including manual 2nd). I'm logging GM.GEAR and can see in the logs it shows 2, but it doesn't 'feel' like its getting 2.

If I can confirm where this information is source (e.g. requested gear from PCM, OR feedback from transmission pillow switches to indicate shift selection), I can potentially rule out a bunch of areas I've played with (or not).

You should see engine rpm and vehicle speed correspond correctly...

Post tune and logs.

Quote:

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Originally Posted by joecar

You should see engine rpm and vehicle speed correspond correctly...

Post tune and logs.

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If only it was that easy to tell... :)

- I've never driven a car with a stall
- I've never driven a car with a 4L80e (different gear ratios to a 4L60e)
- Engine is loud

I believe I've found the source of the problem, but for the purpose of closing out this question lets keep the discussion going. While I was unclear/unsure of it before, it is pretty safe to say that I do NOT have 2nd gear in the log attached.

Log file and tune attached.

Attachment 23952
Attachment 23953

There is a parameter to set the current gear based on the pressure control solenoid inside the trans. Set the PRNDL to none IIRC.

While I'm still chasing confirmation, I believe the data output of GM.GEAR is actually the requested gear position from the PCM without any feedback from the pillow switches inside the transmission at all. The reason I was missing 2nd gear was a physically missing lip seal which would apply 2nd gear in the transmission. While I don't believe there would've actually been enough pressure under the pillow switch to apply this button, it would have helped with my troubleshooting before pulling the transmission out.