A/T System Description - Electrical Control System

Electronic Control System


Electronic Control

The electronic control system consists of the powertrain control module (PCM), sensors, and seven solenoid valves.
Shifting and lock-up are electronically controlled for comfortable driving under all conditions.

The PCM receives input signals from the sensors, switches, and other control units, processes data, and outputs signals for the engine control system and A/T control system. The A/T control system includes shift control, grade logic control, clutch pressure control, and lock-up control. 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.

 

Electronic Control System (cont'd)


Electronic Controls Locations: LHD model

 

 

Electronic Controls Locations: RHD model

 

 

Electronic Control System (cont'd)


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, and D to control shifting transmission gear.

Shift solenoid valves use ON-OPEN/OFF-CLOSE type; shift solenoid valve opens the port of shift solenoid valve pressure leading to shift valves while shift solenoid valve is turned ON by the PCM, and closes the port when shift solenoid valve is OFF.

The combination of driving signals to shift solenoid valves A, B, C, and D are shown in the table.

Position Gear Position Shift Solenoid Valve 
D, D3, S Shifting from the N position OFF OFF OFF OFF 
Stays in 1st OFF ON OFF ON or OFF 
Shifting gears between 1st and 2nd ON ON OFF ON or OFF 
Stays in 2nd ON OFF OFF ON or OFF 
Shifting gears between 2nd and 3rd OFF OFF OFF ON or OFF 
Stays in 3rd OFF OFF ON ON or OFF 
D, S Shifting gears between 3rd and 4th ON OFF ON ON or OFF 
Stays in 4th ON ON ON ON or OFF 
Shifting gears between 4th and 5th OFF ON ON ON or OFF 
Stays in 5th OFF ON OFF ON or OFF 
2nd ON OFF OFF OFF 
1st OFF ON OFF OFF 
Neutral OFF OFF OFF OFF 
Shifting from the P and N positions OFF OFF ON ON 
Stays in reverse OFF ON ON ON 
Reverse inhibit control ON OFF ON OFF 
Park OFF OFF OFF ON 

Shift Control - Grade Logic Control

Also, the grade logic control system has been adopted to control shifting in the D position. The PCM compares actual driving conditions with programmed driving conditions, based on the input from the accelerator pedal position sensor, the throttle position sensor, the engine coolant temperature sensor, the barometric pressure sensor, the brake pedal position switch signal, and the shift lever position signal, to control shifting while the vehicle is ascending or descending a slope.

 

Electronic Control System (cont'd)


Grade Logic Control: Ascending Control

When the PCM determines that the vehicle is climbing a hill in the D position, the system extends the engagement area of 2nd gear, 3rd gear, and 4th gear 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.

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

 

Grade Logic Control: Descending Control

When the PCM determines that the vehicle is going down a hill in the D position, the shift-up speed from 4th to 5th gear, 3rd to 4th gear, and from 2nd to 3rd (when the throttle is closed) becomes faster than the set speed for flat road driving to widen the 4th gear, 3rd gear, and 2nd gear driving areas. This, in combination with engine braking from the deceleration lock-up, achieves smooth driving when the vehicle is descending. There are three descending modes with different 4th gear driving areas, 3rd gear driving areas and 2nd gear driving areas according to the magnitude of a gradient stored in the PCM. When the vehicle is in 5th or 4th gear and you are decelerating while applying the brakes on a steep hill, the transmission will downshift to a lower gear. When you accelerate, the transmission will then return to a higher gear.

 

Shift Control - S-position Automatic Shift Mode and Sequential Shift Mode

The S position of the 5-position transmission has two modes; S-position automatic shift mode and sequential shift mode. The transmission switches to the S-position automatic shift mode when the shift lever is shifted into the S position. In the S-position automatic shift mode, the transmission shifts automatically 1st gear through 5th gear same as in the D position, and the steering wheel shift switches are ready to be activated switching to sequential shift mode. When the steering wheel upshift (+) switch or downshift (-) switch is activated, the S-position automatic shift mode will be cancelled and sequential shift mode comes into operation. In the sequential shift mode, the driver can shift up and down manually between 1st through 5th gears with using the steering wheel upshift (+) switch and downshift (-) switch; much like a manual transmission. The sequential shift mode is cancelled when the shift lever is moved to any position other than S.

The steering wheel upshift (+) switch and steering wheel downshift (-) switch are installed back of the steering wheel. The driver can shift gears with pressing the steering wheel shift switches without taking either hand off the steering wheel.

 

The M indicator and shift indicator are next to the tachometer in the gauge control module (tach).

 

In the S-position automatic shift mode, the shift indicator displays the number of currently-selected gear. The M indicator does not come on in automatic shift mode, when the transmission switches into the sequential shift mode by pressing the steering wheel shift switches, the M indicator comes on, and the shift indicator displays the number of the selected gear.

Electronic Control System (cont'd)


Clutch Pressure Control

The PCM actuates the A/T clutch pressure control solenoid valves A, B, and C to control the clutch pressure. When shifting between gears, the clutch pressure regulated by the A/T clutch pressure control solenoid valves A, B, and C engages and disengages the clutch smoothly.
The PCM receives input signals from the various sensors and switches, processes data, and outputs current to the A/T clutch pressure control solenoid valves A, B, and C.

 

Lock-up Control

The shift solenoid valve D controls the hydraulic pressure to switch the lock-up shift valve and lock-up ON and OFF. The PCM actuates the shift solenoid valve D and the A/T clutch pressure control solenoid valve A to start lock-up. The A/T clutch pressure control solenoid valve A applies and regulates hydraulic pressure to the lock-up control valve to control the volume of the lock-up.
The lock-up mechanism operates in the D position (1st, 2nd, 3rd, 4th, and 5th), and in the D3 position (1st, 2nd, and 3rd).

 

Electronic Control System (cont'd)


PCM A/T Control System Electrical Connections - 7-position Automatic Transmission

 

PCM A/T Control System Electrical Connections - 5-position Automatic Transmission

 

Electronic Control System (cont'd)


PCM A/T Control System Inputs and Outputs

 

PCM CONNECTOR A (44P)
Terminal Number Wire Color Signal Description Measuring Conditions/Terminal Voltage 
A27 PNK SLS Shift lock solenoid signal input With ignition switch ON (II), in the P position, brake pedal pressed, and accelerator released: 0 V 
A31 BRN SCS Detects service check signal With the SCS shorted with the HDS: About 0 V
With the SCS open: About 5 V 
A36 WHT CAN H Communication signal outputs With ignition switch ON (II): About 2.5 V (pulse) 
A37 RED CAN L Sends communication signal With ignition switch ON (II): About 2.5 V (pulse) 
A40 LT GRN BK SW Detects brake pedal position switch signal Brake pedal pressed: Battery voltage
Brake pedal released: 0 V 

PCM CONNECTOR B (44P)
Terminal Number Wire Color Signal Description Measuring Conditions/Terminal Voltage 
B1 BLK PG2 Ground  
B8 BLU/YEL OP2SW Detects 2nd clutch transmission fluid pressure switch signal With ignition switch ON (II):
  • Without 2nd clutch pressure: About 5 V
  • With 2nd clutch pressure: About 0 V
 
B9 BLK/RED OP3SW Detects 3rd clutch transmission fluid pressure switch signal With ignition switch ON (II):
  • Without 3rd clutch pressure: About 5 V
  • With 3rd clutch pressure: About 0 V
 
B10 BLU SH A Shift solenoid valve A control In the 2 position, D position in 2nd and 4th gears, and D3 position in 2nd gear: Battery voltage
In the P, R, N, and 1 positions, D position in 1st, 3rd, and 5th gears, and D3 position in 1st and 3rd gears: 0 V 
B11 GRN/RED SH D Shift solenoid valve D control In the P and R positions: Battery voltage
In the N position: 0 V 

PCM CONNECTOR B (44P)
Terminal Number Wire Color Signal Description Measuring Conditions/Terminal Voltage 
B12 RED/BLK ATP N Detects transmission range switch N position signal In the N position: About 0 V
In other than the N position: About 5 V 
B13 BLU/BLK ATP P Detects transmission range switch P position signal In the P position: About 0 V
In other than the P position: Battery voltage 
B14 WHT/GRN ATP R Detects transmission range switch R position signal In the R position: About 0 V
In other than the R position: Battery voltage 
B15
(7-position) 
RED ATP D3 Detects transmission range switch D3 position signal In the D3 position: About 0 V
In other than the D3 position: Battery voltage 
B15
(5-position) 
RED ATP S Detects transmission range switch S position signal In the S position: About 0 V
In other than the S position: Battery voltage 
B16
(7-position) 
BRN ATP 2-1 Detects transmission range switch 2 position signal and 1 position signal In the 2 and 1 positions: About 0 V
In other than the 2 and 1 positions: Battery voltage 
B16
(5-position) 
BLU/YEL S-UP Inputs steering wheel upshift (+) switch signal In the S position
  • Steering wheel upshift (+) switch pressed: 0 V
  • Steering wheel upshift (+) switch released: About 5 V
 
B17 WHT/RED NM Inputs input shaft (mainshaft) speed sensor signal With ignition switch ON (II): About 0 V or about 5 V
With engine at idle in the N position: About 2.5 V 
B18 YEL/BLU VCC2 Power supply for sensors With ignition switch ON (II): About 5 V
With ignition switch OFF: About 0 V 
B20 GRN SH C Shift solenoid valve C control In the R position, D position in 3rd and 4th gears, and D3 position in 3rd gear: Battery voltage
In the P, N, 2, and 1 positions, D position in 1st, 2nd, and 5th gears, and D3 position in 1st and 2nd gears: 0 V 
B21 YEL/GRN ATP D Detects transmission range switch D position signal In the D position: About 0 V
In other than the D position: Battery voltage 
B22 YEL ATP RVS Detects transmission range switch RVS switch signal In the R position: About 0 V
In other than the R position: Battery voltage 
B25 BLU/WHT LS C A/T clutch pressure control solenoid valve C control With ignition switch ON (II): Current controlled 
B26 GRN/WHT SH B Shift solenoid valve C control In the R and 1 positions, D position in 1st, 4th, and 5th gears, and D3 position in 1st gear: Battery voltage
In the P, N, and 2 positions, and D, D3 positions in 2nd and 3rd gears: 0 V 
B27 BRN/RED ATFT Inputs ATF temperature sensor signal With igniting switch ON (II): 0.2-4.8 V
With ignition switch OFF: About 0 V 

Electronic Control System (cont'd)


PCM A/T Control System Inputs and Outputs (cont'd)

 

PCM CONNECTOR B (44P)
Terminal Number Wire Color Signal Description Measuring Conditions/Terminal Voltage 
B28
(7-position) 
BLU/YEL ATP FWD Detects transmission range switch D, D3, and 2 positions signal In the D, D3, and 2 positions: 0 V
In other than the D, D3, and 2 positions: Battery voltage 
B28
(5-position) 
BLU/YEL ATP FWD Detects transmission range switch D and S positions signal In the D and S positions: 0 V
In other than the D and S positions: Battery voltage 
B33 GRN/YEL SG2 Sensor ground  
B35 WHT LS A A/T clutch pressure control solenoid valve A control With ignition switch ON (II): Current controlled 
B36 BLK PG1 Ground  
B40 BRN S-DN Inputs steering wheel downshift (-) switch signal In the S position
  • Steering wheel downshift (-) switch pressed: 0 V
  • Steering wheel downshift (-) switch released: About 5 V
 
B44 BRN/WHT LS B A/T clutch pressure control solenoid valve B control With ignition switch ON (II): Current controlled 

PCM CONNECTOR C (44P)
Terminal Number Wire Color Signal Description Measuring Conditions/Terminal Voltage 
C13 YEL/RED VCC1 Power supply circuit With ignition switch ON (II): About 5 V
With ignition switch OFF: About 0 V 
C14 GRN/WHT SG1 Sensor ground  
C36 BLK/YEL IG1 Power supply circuit With ignition switch ON (II): Battery voltage
With ignition switch OFF: 0 V 
C40 BRN/YEL LG1 Ground  
C43 BLK/BLU NC Inputs output shaft (countershaft) speed sensor signal With ignition switch ON (II): About 0 V or about 5 V
With driving: Pulsing signal (0-5 V) 
C44 BRN/YEL LG2 Ground