transmission related notes
GenBoard/VerThree could control automatic transmission: HW (input, output and numbercrunch-power) is sufficient but it would require about 1000..2000 (estimated) lines of code (read: not implemented yet).
Cooperating with factory autotrans
Many automatic gearboxes are individual units, that only need some signals from the engine (or signals common with the engine):
- RPM (or they measure RPM of the input shaft themselves)
- TPS signal: this is always needed for an automatic transmission
- CLT or oil temperature
- VBatt (for solenoid current control), they usually measure VBatt themselves
Some automatic gearboxes share the brain with the engine (ECM controls automatic gearbox solenoids). This is rare, but getting more frequent. Such a beast needs all signals that engine management requires. It's not tricky to get the inputs to unit, and fake resistors on injector outputs (if it detects injector current, to make it believe injectors are there). however such a unit usually instructs (with an internal command signal) the engine to decrease torque for a moment while switching. This is usually
- minor issue for planet-gear autotrans, but
- huge issue for sequential gearbox (like the ones used on F1 and their manual cousins on motorcycles)
You need to look up the manual of the gearbox to find out more. The popular 40L60E and 40L80E series feature an individual brain, easy to get working with an aftermarket ECM (see MembersPage/ChrisGerhardt).
Some information about the 4L80E and 4L60E taken from memory: -Jörgen
Both transmissions use:
- 3 pressure switches to determine in which position the shift lever is. (add array)
- 2 shift solenoids. (add array, resistance and pwm if applicable)
- 1 pressure control solenoid, this is used to soften the shifts at low power. 0% PWM = full pressure = minimal slipping. Find resistance of solenoid and suitable PWM frequency.
- 1 Converter lockup solenoid, current limited with PWM. Find resistance and frequency.
Find pinouts for the most common variants of the transmissions.
Tunable TCU (Transmission-Control-Unit)s: