411 PCM auto trans I/O pins
Posted: Sat Mar 24, 2018 11:46 am
The 411 PCM has a few pins that were used as inputs and outputs for sensors and actuators in automatic transmissions, and I'm wondering if those pins could be put to more interesting uses in manual-transmission cars.
According to the pinout at http://www.lt1swap.com/99-02_vortec_pcm.htm
Blue connector pins:
17 - trans fluid pressure switch b (presumably a binary input)
18 - trans fluid pressure switch c (ditto)
32 - PRND "A" input (not sure if digital or analog, likely digital)
24 - PRND "P" input (apparently binary, park/neutral)
79 - 2/3 shift solenoid control (what kind of control signal? binary, analog, PWM, etc?)
Red connector pins:
2 - TCC control solenoid (what kind of signal?)
6 - transmission fluid pressure control solenoid high (what kind of signal?)
8 - transmission fluid pressure control solenoid low
47 - transmission shift solenoid A (what kind of signal?)
48 - transmission shift solendoi B (what kind of signal?)
51 - transmission temperature signal - ?
The web page says this last pin is used only for AT, but I have a hunch my MT Corvette might use it for the transmission temp display in the instrument cluster.
If the solenoid outputs are PWM then one of them could presumably be re-purposed for boost control on forced-induction cars, with some hacking of the PCM firmware of course. Since the PCM knows throttle, RPM, and vehicle speed, one could presumably set up per-gear boost control tables.
An analog could potentially be re-purposed for use with an ethanol sensor for flex-fuel, again with some firmware hacking.
A digital input could be re-purposed as a valet switch to limit throttle on drive-by-wire cars to, say, 50%. Or limit RPM to 4000 on cable-throttle cars.
But since I've never paid much attention to how automatic transmissions work, I have no idea what sorts of signals these I/O pins were intended for. Does anyone know?
And while I realize that it's kind of early to start talking about this degree of firmware hacking for these PCMs, I'm pretty optimistic about the near future.
According to the pinout at http://www.lt1swap.com/99-02_vortec_pcm.htm
Blue connector pins:
17 - trans fluid pressure switch b (presumably a binary input)
18 - trans fluid pressure switch c (ditto)
32 - PRND "A" input (not sure if digital or analog, likely digital)
24 - PRND "P" input (apparently binary, park/neutral)
79 - 2/3 shift solenoid control (what kind of control signal? binary, analog, PWM, etc?)
Red connector pins:
2 - TCC control solenoid (what kind of signal?)
6 - transmission fluid pressure control solenoid high (what kind of signal?)
8 - transmission fluid pressure control solenoid low
47 - transmission shift solenoid A (what kind of signal?)
48 - transmission shift solendoi B (what kind of signal?)
51 - transmission temperature signal - ?
The web page says this last pin is used only for AT, but I have a hunch my MT Corvette might use it for the transmission temp display in the instrument cluster.
If the solenoid outputs are PWM then one of them could presumably be re-purposed for boost control on forced-induction cars, with some hacking of the PCM firmware of course. Since the PCM knows throttle, RPM, and vehicle speed, one could presumably set up per-gear boost control tables.
An analog could potentially be re-purposed for use with an ethanol sensor for flex-fuel, again with some firmware hacking.
A digital input could be re-purposed as a valet switch to limit throttle on drive-by-wire cars to, say, 50%. Or limit RPM to 4000 on cable-throttle cars.
But since I've never paid much attention to how automatic transmissions work, I have no idea what sorts of signals these I/O pins were intended for. Does anyone know?
And while I realize that it's kind of early to start talking about this degree of firmware hacking for these PCMs, I'm pretty optimistic about the near future.