A/T System Description - Electrical Control System (K20Z: A/T)

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 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, D and E 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, D, and E are shown in the table.

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

Position	Gear Position	Shift Solenoid Valve
D and S	Shifting from the N position	OFF	ON	ON	OFF	OFF
Stays in 1st	ON	ON	ON	OFF	OFF
Shifting gears between 1st and 2nd	OFF	ON	ON	OFF	OFF
Stays in 2nd	OFF	ON	OFF	ON	OFF or ON
Shifting gears between 2nd and 3rd	OFF	ON	ON	ON	OFF or ON
Stays in 3rd	OFF	OFF	ON	OFF	OFF or ON
Shifting gears between 3rd and 4th	OFF	OFF	OFF	OFF	OFF or ON
Stays in 4th	ON	OFF	OFF	OFF	OFF or ON
Shifting gears between 4th and 5th	ON	OFF	OFF	ON	OFF or ON
Stays in 5th	ON	OFF	ON	ON	OFF or ON
N	Neutral	OFF	ON	ON	OFF	OFF
R	Shifting from the P and N positions	OFF	ON	OFF	OFF	ON
Stays in reverse	ON	ON	OFF	OFF	ON
Reverse inhibit control	ON	ON	OFF	OFF	OFF
P	Park	OFF	ON	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 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 E controls the hydraulic pressure to switch the lock-up shift valve and lock-up ON and OFF. The PCM actuates the shift solenoid valve E 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 and S positions (2nd, 3rd, 4th, and 5th).

Electronic Control System (cont'd)

PCM A/T Control System Electrical Connections

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 Inputs shift lock solenoid signal 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 A (44P)**
Terminal Number	Wire Color	Signal	Description	Measuring Conditions/Terminal Voltage
A27	PNK	SLS	Inputs shift lock solenoid signal	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/RED 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/WHT 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 Drives shift solenoid valve A In the R position, D and S positions in 1st, 4th, and 5th gears: Battery voltage
In the P and N positions, D and S position in 2nd and 3rd gears: 0 V
B11 GRN/WHT SH B Drives shift solenoid valve B In the P, R, and N positions, D and S positions in 1st and 2nd gears: Battery voltage
In the D and S positions in 3rd, 4th, and 5th gears: 0 V

**PCM CONNECTOR B (44P)**
Terminal Number	Wire Color	Signal	Description	Measuring Conditions/Terminal Voltage
B1	BLK	PG2	Ground
B8	BLU/RED	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/WHT	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	Drives shift solenoid valve A	In the R position, D and S positions in 1st, 4th, and 5th gears: Battery voltage In the P and N positions, D and S position in 2nd and 3rd gears: 0 V
B11	GRN/WHT	SH B	Drives shift solenoid valve B	In the P, R, and N positions, D and S positions in 1st and 2nd gears: Battery voltage In the D and S positions in 3rd, 4th, and 5th gears: 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
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 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 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 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 Supplies power for sensors With ignition switch ON (II): About 5 V
With ignition switch OFF: About 0 V
B20 GRN SH C Drives shift solenoid valve C In the N position, D and S positions in 1st, 3rd, and 5th gears: Battery voltage
In the P and R positions, D and S positions in 2nd and 4th 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 RED/WHT ATP RVS Detects transmission range switch RVS switch signal In the R position: About 0 V
In other than the R position: Battery voltage

**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	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	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	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	Supplies power for sensors	With ignition switch ON (II): About 5 V With ignition switch OFF: About 0 V
B20	GRN	SH C	Drives shift solenoid valve C	In the N position, D and S positions in 1st, 3rd, and 5th gears: Battery voltage In the P and R positions, D and S positions in 2nd and 4th 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	RED/WHT	ATP RVS	Detects transmission range switch RVS switch signal	In the R position: About 0 V In other than the R position: Battery voltage

PCM CONNECTOR B (44P)
Terminal Number Wire Color Signal Description Measuring Conditions/Terminal Voltage
B24 YEL SH E Drives shift solenoid valve E In the P and R positions: Battery voltage
In the N position, D and S positions in 1st gear: 0 V
B25 BLU/YEL LS C Drives A/T clutch pressure control solenoid valve C With ignition switch ON (II): Carrent controlled
B26 GRN/RED SH D Shift solenoid valve D control In the D and S positions in 2nd and 5th gears: Battery voltage
In the P, R, and N positions, D and S positions in 1st, 3rd, and 4th gears: 0 V
B27 RED/YEL ATFT Inputs ATF temperature sensor signal With igniting switch ON (II): 0.2-4.8 V
With ignition switch OFF: About 0 V
B28 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/BLK SG2 Sensor ground
B35 BRN LS B Drives A/T clutch pressure control solenoid valve B 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 RED/BLK LS A Drives A/T clutch pressure control solenoid valve A With ignition switch ON (II): Current controlled

**PCM CONNECTOR B (44P)**
Terminal Number	Wire Color	Signal	Description	Measuring Conditions/Terminal Voltage
B24	YEL	SH E	Drives shift solenoid valve E	In the P and R positions: Battery voltage In the N position, D and S positions in 1st gear: 0 V
B25	BLU/YEL	LS C	Drives A/T clutch pressure control solenoid valve C	With ignition switch ON (II): Carrent controlled
B26	GRN/RED	SH D	Shift solenoid valve D control	In the D and S positions in 2nd and 5th gears: Battery voltage In the P, R, and N positions, D and S positions in 1st, 3rd, and 4th gears: 0 V
B27	RED/YEL	ATFT	Inputs ATF temperature sensor signal	With igniting switch ON (II): 0.2-4.8 V With ignition switch OFF: About 0 V
B28	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/BLK	SG2	Sensor ground
B35	BRN	LS B	Drives A/T clutch pressure control solenoid valve B	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	RED/BLK	LS A	Drives A/T clutch pressure control solenoid valve A	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 Supplies power for sensors With ignition switch ON (II): About 5 V
With ignition switch OFF: About 0 V
C14 GRN/WHT SG1 Sensor ground
C36 BLK/GRN IG1 Supplies power for PCM With ignition switch ON (II): Battery voltage
With ignition switch OFF: 0 V
C40 BRN/YEL LG1 Ground
C43 BLK/WHT 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

Terminal Number	Wire Color	Signal	Description	Measuring Conditions/Terminal Voltage
C13	YEL/RED	VCC1	Supplies power for sensors	With ignition switch ON (II): About 5 V With ignition switch OFF: About 0 V
C14	GRN/WHT	SG1	Sensor ground
C36	BLK/GRN	IG1	Supplies power for PCM	With ignition switch ON (II): Battery voltage With ignition switch OFF: 0 V
C40	BRN/YEL	LG1	Ground
C43	BLK/WHT	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