Transfer Box Control Module Outputs
The transfer box control module sends the following outputs:
- CAN bus messages
- Key interlock solenoid
- High/low range change LED
- Transfer box motor
- Solenoid.
CAN BUS MESSAGES
The control module also sends messages via the CAN bus to tell other control modules on the network, the status of the transfer box. The high/low status, clutch torque and default mode status are some of the main signals sent out by the transfer box control module.
KEY INTERLOCK SOLENOID
The transfer box control module is able to send a signal to the key interlock solenoid. This signal locks the key in the ignition barrel to prevent it from being removed if the automatic transmission is not in the 'Park' position.
HIGH/LOW RANGE CHANGE LED
| ITEM | DESCRIPTION |
|---|---|
| 1 | High range LED |
| 2 | Low range LED |
The control module is responsible for illuminating the 2 'high/low' range change LED's adjacent to the range change lever. One LED indicates high range and the other indicates low range.
One LED will be on continuously when in the corresponding range.
When changing range, the current range LED will remain on until the new range status has been achieved.
The new range LED will start flashing only when the range change has commenced (i.e. speed and neutral conditions have been met). The new range LED will be illuminated continuously at the same instant that the current range (now the old range) LED turns off.
The flash rate is 2 Hz with a 50% duty cycle.
The LED's have 2 levels of intensity, high when the vehicle lights are switch off and low when they are switched on.
If both lights are flashing at 0.5 Hz, this would indicate a transfer box fault or that the transfer box is in undefined range and may require calibration.
TRANSFER BOX MOTOR
The transfer box motor provides the necessary movement to perform the high/low range change and the multi-plate clutch actuation. The motor is located on the rear casing assembly and secured with four bolts.
The motor is a PWM controlled, DC motor with an integrated worm gear reduction drive. It is connected to the transfer box control module with an eight-pin connector; the power supply of the motor is maintained through two large diameter cables on the motor connector. An internal position sensor checks the rotational movement of the motor.
There is an temperature sensor located within the motor housing.
SOLENOID
The solenoid switches the power flow on the actuation system between high/low range change mode and clutch control mode. When the solenoid is energized, the solenoid pin deploys and activates the clutch control mode. When the solenoid is de-energized, the internal spring rejects the solenoid pin and activates the high/low range change mode.
The solenoid is connected to the transfer box control module with a two-pin connector.
STATUS INDICATION
Instrument Cluster
| ITEM | DESCRIPTION |
|---|---|
| A | High-line instrument cluster |
| B | Low-line instrument cluster |
| 1 | Low-range status indicator |
| 2 | Message center text (high-line only) |
| 3 | Driveline fault lamp |
| 4 | Driveline over temperature |
On vehicles fitted with the high line instrument cluster there will be one low range status indicator. This indicator will take the form of a mountain symbol and has the following logic:
- Lamp on = low range
- Lamp off = high range
- Lamp flashing = range change in progress/range undefined/range fault.
There will also be a message displayed in the message center, on vehicles with high-line instrument cluster, which will inform the driver of any faults with the transfer box.
The following table shows the messages that can be displayed in the message center of a high-line instrument cluster relating to the transfer box:
| MESSAGE | DESCRIPTION | CHIME |
|---|---|---|
| 'LOW RANGE ENGAGED' | Transfer case has engaged low range after a range change request | Single |
| 'HIGH RANGE ENGAGED' | Transfer case has engaged high range after a range change request | Single |
| 'SPEED TOO HIGH FOR RANGE CHANGE' | Range change request when vehicle speed too high | Single |
| 'SELECT NEUTRAL FOR RANGE CHANGE' | Range change request when lever not in neutral | Single |
| 'APPLY HANDBRAKE' (PARK BRAKE in USA and Canada) | This alerts the driver that the automatic transmission park lock function is inoperative due to transfer box out of high or low range. Transfer box control module has stopped transmitting on the CAN bus during a range change or while in neutral mode and as a result the automatic transmission park lock function is inoperative |
One per second for three seconds |
| 'TRANSMISSION RANGE CHANGE NOT AVAILABLE' | Transfer box has detected a fault inhibiting a new range change. Control unit has shut down due to thermal overload | Single |
| 'CENTRE DIFF OVER TEMP REDUCE SPEED' | Centre differential temperature is approaching the over heated threshold | Single |
| 'CENTRE DIFF FAULT - TRACTION REDUCED' | Centre differential has failed - operating as an open differential | Single |
| 'CENTRE DIFF FAULT - TRACTION REDUCED' | Transfer box control module has stopped transmitting on the CAN bus and defaults to open center differential | Single |
The transfer box control module receives a gear position signal from the manual transmission gear position sensor and publishes the status on the CAN bus. This is displayed in the odometer display, similar to how the automatic transmission displays gear information.
| ODOMETER DISPLAY | DESCRIPTION |
|---|---|
| N | Transmission is in neutral |
| 1 | Transmission is in first gear |
| 2 | Transmission is in second gear |
| 3 | Transmission is in third gear |
| 4 | Transmission is in forth gear |
| 5 | Transmission is in fifth gear |
| 6 | Transmission is in sixth gear |
| R | Transmission is in reverse gear (Japan only) |
| Blank display | Transmission is between neutral and a gear |
| E | Transmission gear position sensor has a fault |
On vehicles fitted with the low line instrument cluster, in place of the message center there will be a status lamp, which has the following logic:
- Amber - Over temperature
- Red - Failure, stop vehicle
The following table shows the faults that could possibly illuminate the transfer box status lamp on vehicles fitted with the low-line instrument cluster:
| INDICATION | DESCRIPTION |
|---|---|
| OFF | Transfer box is operating at normal working temperature |
| YELLOW WARNING LAMP ON | Transfer box temperature is approaching the over heated threshold |
| YELLOW WARNING LAMP ON | Transfer box has detected a fault, which affects the range change function (current range is still maintained) or the center differential has failed to open. |
| RED WARNING LAMP ON | Transfer box has detected a fault which renders the transmission park lock function inoperative due to out of range condition, OR center differential has failed with a nonzero locking torque |
| YELLOW WARNING LAMP ON | Transfer box control module has stopped transmitting on the CAN bus and defaults to open center differential |
| RED WARNING LAMP ON | Transfer box control module has stopped transmitting on the CAN bus during a range change or while in neutral mode and as a result the automatic transmission park lock function is inoperative |