4L65e swA/swB/swC pressure control switch not responding

[mcneil]

This may be a transmission problem and have nothing to do with the MegaShift, but please offer any advice you can. It looks like my pressure control switch is bad, but I want to ask before I tear into the transmission to replace it.

I have my 4L65e installed in my jeep behind a VW 1.9L TDI. The trans was rebuilt at a shop about 3 years ago, when I started the project, and hasn't been driven since the rebuild. I have the TDI running, but the jeep hasn't moved in since I've been working on it. Gear selector, wiring, pressure lines, all that is hooked up and checked out.

The pressure control switch doesn't change at all with gear selector movement. I also am seeing zero line pressure at idle, and Tunerstudio doesn't show the "TCC OFF". Log and files attached.

My MShift is built up according to instructions, and bench tested fine with a trans stim before I installed it. swA/swB/swC indicated correctly. I pulled the connector out and attached my transstim underneath the jeep, and swA/swB/swC functioned correctly. Hooking up to the transmission, the pins R, N, & P, are all either open or 2-50 ohms. Resistance doesn't change with selector movement and the engine off.

The transmission is a 4L65e from something like 2005-2009. No input speed sensor. I followed the 4L60e wiring, so my question is; Did GM do anything different with interal wiring on these? Did I miss a ground somewhere? Are there different version of the pressure control switch?

[Bernard Fife]

mcneil,

As far as I know, there were no significant change in the pressure switch manifold (PSM) between 1993 and 2008. In 2009 they changed to a completely different setup called an "internal mode switch".

You have a steady signal on the inputs:
sw1 (swA) = 4.78V
sw2 (swB) = 0.00V
sw3 (swC) = 4.71V

This is the pattern you have set for Park/Neutral, and that's the manual gear lever position shown (and also what is correct for the 4L65e).

I tried your settings on my bench, a (with 4.146 code) and the controller responds appropriately to change in the states of sw1/sw2/sw3. So I think your basic setup is okay.

You might want to check the voltges at the ampseal connector and the 25x2 connector in various lever positions, if these are convenient to check with the engine running.

However 4.145 is fairly old code. If this was mine, I would update to more current 5.100 release code which was released yesterday and which has a number of fixes for non-CANbus users like you. You can find it here: http://www.msgpio.com/manuals/mshift/V5code.html

If this was mine, I would also:
- Set 'Lever Error Behavior' to 'ignore lever errors' under 'General Settings -> Error Behavior', and
- Set 'Max. Lever Position Change' to '4' under 'Shift Input Patterns -> Lever and Shift Buttons Configuration'
These might not help, but it could make troubleshooting easier.

Finally, the switch manifold itself might not be physically responding. When this is the case, you get the 5v-0v-5v output pattern you are seeing. This can be the result of stuck switches (usually caused by debris) or low line pressure. If you have the tools to measure the line pressure directly, you might want to try that.

Lance.

[mcneil]

Thanks, I got into it again this morning. There does appear to be line pressure at the cooler lines, but I am going to get a gauge on it in case there's something going on with the spin-on trans filter I added. It's the Derale kit, with a PH258 filter. The filter specs say it does have a anti-drainback valve and a 12 psi bypass valve, but something may be wrong in that.

I'll pull the pan off later and make sure the pressure control switch is working.