4WD Control System Description

4WD Control System Description

Transfer Shift Control
The 4WD control module controls the transfer shift actuator based on the signal from the transfer switch so that the transfer is shifted to the selected position (4H, 4H-lock, N or 4L-lock). (Shifting to the N position requires that the switch to "D" position (1) keep it there for about 10 seconds then turn it to "N" position.)

The transfer actuator consists of the actuator motor and the actuator motor position switch. The 4WD control module detects the position of the actuator motor using the position switch and controls the actuator motor running / stopping operation.

Also, the 4L/N switch and center differential lock switch that detect the each position of the High / Low shift fork and the differential lock shift fork are installed the transfer assembly. The 4WD control module detects the transfer actual shift position (4H, 4H-lock, N or 4L-lock) by the signals from the 4L/N switch and center differential lock switch as follows.

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Relationship of transfer shift position and switches

When the transfer shift actuator motor position detected by motor position switch and transfer actual shift position detected by the above-mentioned switches match, the 4WD control module judges that the transfer shifting is complete.

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 Buzzer Operation

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The 4WD control module output operation signal of the differential lock indicator, 4L indicator, N indicator and the buzzer to BCM. Indicators and buzzer as follows in order to inform what state the transfer control system is.

Function of 4WD Control System Component

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4WD Control System Operation
Instead of the transfer shift lever assembly, the transfer position (4H, 4H-lock, N and 4L-lock) is shifted automatically by operating the transfer switch. The 4WD control module operates the transfer shift actuator according to the transfer switch operation.

4H (4WD High) Position
The driving force from the transmission is transmitted to the transfer input gear. As the center LSD case and transfer input gear are engaged via the reduction shift sleeve at this time, the driving force transmitted from the transfer input gear to the rear output shaft rotates them at the same speed.

Also, driving force from the center LSD is transmitted to the front drive shaft through front drive sprocket. Then, the front drive sprocket rotates the front output shaft via the drive chain.








4H-lock (4WD High Center Differential Lock) Position
When 4H-lock position is selected from 4H position by turning the transfer switch, the transfer shift control actuator motor runs and shift cam rotates in the arrow direction "A". The shift cam shifts the differential lock shift fork in the arrow direction "B", and the differential lock clutch sleeve also moves in the arrow direction "B".

The driving force from the transmission is transmitted from the transfer input gear to the rear output shaft, as in the case of 4H position. Also, as the front drive shaft and front drive sprocket bush are engaged via differential lock clutch sleeve, the driving force from the input gear is locked and transmitted to the rear output shaft.








N (Neutral) Position
When N position is selected from 4H position by turning the transfer switch, the transfer shift control actuator motor runs and shift cam rotates in the arrow direction "A". The shift cam shifts the High / Low shift fork in the arrow direction "B", and the reduction shift sleeve moves in the arrow direction "B". Also, the shift cam shifts the differential lock shift fork in the arrow direction "C", and the differential lock clutch sleeve also moves in the arrow direction "C".

The driving force from the transmission is transmitted to the transfer input gear. However, as the reduction shift sleeve is not engaged with the transfer input gear and low gear, the driving force is not transmitted to the rear output shaft and front output shaft.








4L-lock (4WD Low Center Differential Lock) Position
When 4L-lock position is selected from 4H-lock position by turning the transfer switch, the transfer shift control actuator motor runs and shift cam rotates in the arrow direction "A". The shift cam shifts the High/Low shift fork in the arrow direction "B", and the reduction shift sleeve moves in the arrow direction "B". Also, the shift cam shifts the differential lock shift fork in the arrow direction "C", and the differential lock clutch sleeve also moves in the arrow direction "C". The driving force from the transmission is transmitted from the transfer low gear, through the transfer input gear and transfer counter gear with the speed reduced. At this time, as the center LSD case and transfer low gear are engaged via reduction shift sleeve, the driving force is transmitted to the rear output shaft.

The driving force of the rear output shaft makes the front output shaft rotate via the differential lock clutch sleeve as in the case of 4H-lock position.








4WD Control System Wiring Circuit Diagram