3C
4WD Control System Description
The 4WD control system is divided into “Air Locking Hub Control System” and “Transfer control System”.
The transfer control system is described in this section.
NOTE:
• For air locking hub control system description, refer to 4WD Control System Description:Front .
• For details of on-board diagnostic system, refer to On-Board Diagnostic System Description .
Transfer Control System
Instead of the transfer shift lever, the transfer position (2H, 4H and 4L) is shifted automatically by operating the “2WD” switch, “4WD” switch and “4WD-L” switch. The 4WD control module operates the transfer shift actuator according to the “2WD” switch, “4WD” switch and “4WD-L” switch operation. Also, the transfer control system has 4WD indicator, 4WD low indicator and warning buzzer in order to inform the transfer control system condition.
The 4WD control module shifts the transfer to the selected shift position (2H, 4H, or 4L) according to the signal from the “2WD” switch, “4WD” switch or “4WD-L” switch.
The 4WD control module controls the transfer shift actuator in order to operate the shift fork shaft No.1. The 4WD control module detects the position of the transfer shift actuator motor by the signal from the transfer shift actuator limit switch.
Also, the 4WD control module detects each position (2H, 4H, or 4L) of the shift fork shaft No.1 installed to the transfer assembly by the signals from the 4WD switch and the 4WD low switch as follows.
Relationship of transfer shift position and switch
Switch Transfer shift position
2H 4H 4L
4WD switch OFF ON ON
4WD low switch OFF OFF ON
When the transfer shift actuator motor position detected by the limit switch matches the shift fork shaft No.1 position detected by the switches above-mentioned, the 4WD control module judges that the transfer shifting is completed.
Retry Control
When 4WD control module cannot judge the shifting to the target position, it commands to retry the shifting up to 3 times. If retry shifting is not possible, previous shift position is restored and notify failure of the shifting with the indicator and buzzer.
Indicator and warning buzzer operation
The 4WD control module operates the 4WD indicator, the 4WD low indicator and the warning buzzer as follows in order to inform what state the transfer control system is.
NOTE:
For the conditions with asterisk (**) in the table below, the transfer control system is in the limited shift operation. For the details of limited shift operation, refer to Description of Limited Shift Operation .
Operation Condition
Indicator Warning Buzzer
4WD indicator OFF —
• Ignition switch is OFF.
• Transfer is at 2H (air locking hub is unlocked).
ON —
• Within 2 seconds after ignition switch is turned ON.
(checking indicator operation)
• Transfer is at 4H/4L (air locking hub is locked).
Flashes at intervals of 0.5 seconds for approx. 3 seconds —
• Transfer is shifting from 2H to 4H.
• Transfer is shifting from 4H to 2H.
• Transfer could not complete shifting to 2H (or 4H) and shift position is returning to 4H (or 2H)**.
Flashes at intervals of 0.2 seconds continuously with 4WD low indicator — 4WD control module detects DTC of 4WD control system.
Flashes at intervals of 0.5 seconds Sounds 3 times “4WD” switch operates at 100 km/h (62 mile/h) or more when transfer is at 2H**.
4WD low indicator OFF —
• Ignition switch is OFF.
• Transfer is at 2H/4H. (4WD low switch is OFF.)
ON —
• Within 2 seconds after ignition switch is turned ON.
(checking indicator operation)
• Transfer is at 4L. (4WD low switch is ON.)
Flashes at intervals of 0.5 seconds Sounds continuously
• Transfer is shifting from 4H to 4L or from 2H to 4L.
• Transfer is shifting from 4L to 4H or from 4L to 2H.
• Transfer is shifting to shift position detected by 4WD low switch**.
Flashes at intervals of 0.2 seconds continuously with 4WD indicator —
• 4WD control module detects DTC of 4WD control system.
Flashes at intervals of 0.5 seconds Sounds 3 times
• “4WD” switch or “2WD” switch operates at 5 km/h (3 mile/h) or more when transfer is at 4L**.
• “4WD-L” switch operates at 5 km/h (3 mile/h) or more when transfer is at 4H or 2H**.
• Vehicle speed rises by 5 km/h (3 mile/h) or more during shifting from 4H to 4L, from 4L to 4H, from 2H to 4L or from 4L to 2H**.
• A/T select lever shifts to other than “N” range or clutch pedal is released during shifting from 4H to 4L, from 4L to 4H, from 2H to 4L or from 4L to 2H.
• “4WD” switch or “2WD” switch is pushed when transfer is at 4L and A/T is at other than “N” range or clutch pedal is released.
• “4WD-L” switch is pushed when transfer is at 4H or 2H, and A/T is at other than “N” range or clutch pedal is released.