Acura TSX / Honda Accord CL. Manual — part 931

The PCM switches the shift solenoid valves and the A/T clutch pressure control solenoid valves to control
shifting transmission gears and lock-up torque converter clutch.

Fig. 34: Electronic Control System Schematic

Electronic Controls Location

2004 Acura TSX

2004 AUTOMATIC TRANSMISSIONS Diagnosis - MCTA 5-Speed

Fig. 35: Locating Electronic Controls

SHIFT CONTROL

The PCM instantly determines which gear should be selected by various signals sent from sensors and switches,
and it actuates the shift solenoid valves A, B, C, D, and E to control shifting.

Also, a grade logic control system has been adopted to control shifting in D and D

3

positions. The PCM

compares actual driving conditions with memorized driving conditions, based on the input from the throttle
position sensor, the engine coolant temperature sensor, the barometric pressure sensor, the brake pedal position

2004 Acura TSX

2004 AUTOMATIC TRANSMISSIONS Diagnosis - MCTA 5-Speed

switch signal, and the shift lever position signal, to control shifting while the vehicle is ascending or descending
a slope.

Fig. 36: Shift Control Schematic

The PCM turns the shift solenoid valves A, B, C, D, and E ON and OFF to control shifting transmission gear.
The combination of driving signals to shift solenoid valves A, B, C, D, and E are shown in table below.

2004 Acura TSX

2004 AUTOMATIC TRANSMISSIONS Diagnosis - MCTA 5-Speed

Fig. 37: Transmission Gear/Shift Solenoid Valve Table

GRADE LOGIC CONTROL: ASCENDING CONTROL

When the PCM determines that the vehicle is climbing a hill in D and D

3

positions, the system extends the

engagement area of 2nd, 3rd, and 4th gears to prevent the transmission from frequently shifting between 2nd
and 3rd gears, between 3rd and 4th gears, and between 4th and 5th gears, so the vehicle can run smooth and
have more power when needed.

Shift schedules stored in the PCM between 2nd and 3rd gears, between 3rd and 4th gears, and between 4th and
5th gears, enable it to automatically select the most suitable gear according to the magnitude of a gradient.

Fig. 38: Grade Logic Control: Ascending Control Table

GRADE LOGIC CONTROL: DESCENDING CONTROL

When the PCM determines that the vehicle is going down a hill in D and D

3

positions, the shift-up speed from

2004 Acura TSX

2004 AUTOMATIC TRANSMISSIONS Diagnosis - MCTA 5-Speed