Aftermarket Muffler

Normally there is a transmission controller (TCU) that controls the upshifts and downshifts. Different years will quite likely shift differently. Also the TCU and ECU normally cooperate where the ECU will pull timing during an upshift resulting in a drop in power and smoother shift. I don't do a lot of work on autos but I do know on supras everything including the line pressures are controlled by the computer.

-Michael

Normally there is a transmission controller (TCU) that controls the upshifts and downshifts. Different years will quite likely shift differently. Also the TCU and ECU normally cooperate where the ECU will pull timing during an upshift resulting in a drop in power and smoother shift. I don't do a lot of work on autos but I do know on supras everything including the line pressures are controlled by the computer.

-Michael

the A245E and i'm pretty sure the A246E in the 8th gen are only partially hydraulic and partially electronic. theres still a manual throttle valve which increases line pressure when the throttle is depressed and a manual govener valve. from the diagrams ive studied theres no an electronic pressure control solenoid. now i've only looked at the 93-97 A245E and 94-99 A246E. also, on the corolla the ECU and TCU are integrated into whats called a PCM (Powertrain Control Module). The PCM on the 7th gen corolla only controls 3 solenoids in the transmission, the 1st shift solenoid, the 2nd shift solenoid, and the TCC solenoid. 4th (overdrive) is more or less a hydro-electrical circuit that isnt very well explained. it is turned off and on manually, but the inner workings of it are a little more complex. when the switch is on a signal is sent to the PCM, the PCM then at certain speeds knowing what the pressures will be turns the shift solenoids off and on in the right combination along with the TV position and governor position and an underdrive clutch, OD is achieved. the service manual leaves some of this pretty vague, what i need i dont have, which is a solenoid apply chart for the trans ranges.