I was about to ask the same.. For a reverse engineering topic, sure been a lot of crickets bounce thru here...
Topic says "Pins", so lets move to that side for a moment. I've sorted the offsets questions above, and will update those shortly. For now, have a look at our different Range Switch pinouts possibilities. Best I have noted so far, there are 4 possible range switch hardware options used by GM as of posting. Luckily have only found 2 wiring and operational differences, based on 4 or 6 pins. The 6 pins models seems to share hardware characteristics with older GM range switches. Using a single dedicated ground switched P/N safety wire going back to our ECM/PCM in belows first 2019 E92 ECM example. 2014+ 6-spd Allison also share the 6 pin range layout with our 8L45 models. However our 6 and 4 pin switches, now both share 9v Ref lines with our from our new style speed sensors that we will address later.
In this 2019 8L45 M5T Pinout example. The ground pin is provided by the TCM to the internal switch, and signal is passed to ECM.
Next up is our cable shifted Ford 10R80 and GM 10L80/90 models that share the same internal range switch hardware. Along with all other sensors and actuators. But where they split off, is how they wire the range sensors, and the PWM variable duty cycle signals generated. No more single ground wire P/N Safety outputs. Now it's all about CANbus messages, and for GM models that still use a shifter cable, a 5v PWM is telling the ECM and TCM what position that shifter is in. No old 0-5v sweeps, the new sensors produce 2x opposed sweeping 0-100% duty cycle values. Called Sensor A and Sensor B, if you add these two signals together, you should always get 100%.
In the Ford 10R world, they took this as designed and feed both of the range signals to the TCM Only. TCM is then tasked with telling all other nodes what shifter position is over CANbus. Very simple design, where the range switch gets it's Power from the TCM 9v Ref Lines shared with other sensors.
Of-course that OEM hardware and Ford design couldn't fit in GM platfoms,, so they jacked it all up. On the T87A's at least.. GM felt they needed a way to give the ECM's their old style direct P/N signal, not trusting CANbus I guess. So they split the Sensor A and Sensor B signal lines between the ECM and TCM. Then they check the ECM against TCM position using CANbus, to come to a Correlation.. Haven't dove super deep into this correlation deal, but know it will set a MIL if they don't pair up after a couple minutes. Car still shifts, so moving on...
In image below, note how GM chose to power the range switch from an ECM 5v Ref Line rather than the same 9v lines they use in for the 8L models.. Which tells us two things. First, the E92 ECM isn't hardware equipped to handle a 9v signal on any ports. And second, the T87A will obviously read a 5v or 9v PWM signal on it's inputs, so long as the HZ and duty cycles values line up with the tune. I have verified this input emulated on the bench with a 3$ PWM board.
Now that we know our range switch power and pins, this should help anyone trying to up mix and match platform hardware. 6 or 4 pin range, also determines which ECM will fit the build. But for our next point of interest, will need checked using an actual range switch, which I currently don't have on the bench. But while reviewing this data, I quickly noticed that our Ford 10R units PWM duty values don't exactly line up with our GM 10L values. Same sensor, but different supply voltages. Is the cables longer in a Ford, or does that 5v / 9v Ref change our output values?? Time will tell. But it sure would make a cleaner 10L stand-alone option if we can power that range switch from the TCM 9v Ref like Ford, and it line up with map in our tune files without modifications...
Ok crickets, chirp..
