Default/Limp-home Strategy
If a fault occurs with the transfer box, the transfer box control module or one of the required input signals i.e. road speed signal, the control module records an error code and will respond appropriately to provide the highest level of system capability under the specific fault conditions. The following fault states are possible:
| Fault state | System response | Driver warning |
|---|---|---|
| No reduction in capability | Diagnostic Trouble Code (DTC) will be recorded but no effect on performance | Non |
| Clutch control not possible. Temporary over temperature condition | The tractive capability of the vehicle, off road, is reduced. | Driveline over temperature warning lamp or "CENTRE DIFF OVER TEMP REDUCE SPEED" on message centre |
| Clutch control not possible. Permanent fault | The tractive capability of the vehicle, off road, is reduced. | Driveline fault warning lamp or "CENTRE DIFF FAULT TRACTION REDUCED" on message centre |
| Range change not possible | The system inhibits the driver from making a range change | Driveline fault warning lamp or "TRANSMISSION RANGE CHANGE NOT AVAILABLE" on message centre |
| Stuck in Transfer box neutral | The transfer box is stuck between high and low range resulting in no drive to wheels | Flash low range indicator plus "APPLY HANDBRAKE (PARK BRAKE in USA and Canada)". The message will only display at times when it is deemed safe or necessary. It will not display during normal driving for example. |
If a driveline over temperature condition has occurred, after the driveline has been allowed to cool, clutch control will be re-enabled and the warnings will disappear. There is no need to seek service assistance following an over temperature event.
If clutch control or Range change is not possible due to a permanent fault the driver must seek service assistance at the earliest opportunity.
If the system suffers a fault, which causes the transfer box to fail in neutral, the control module is designed to continue attempting to engage the requested range or return to its original range for a fixed number of attempts. If this has not been successful and the low range lamp is still flashing the driver should bring the vehicle to a halt and attempt the range change again while stationary. If this does not work after a number of attempts, key off for 30 seconds, restart engine and request range change again while stationary. The driver must seek service assistance at the earliest opportunity.