Transfer Box ECU

Transfer Box ECU







The transfer box ECU is located behind the battery, on the bulkhead.

The transfer box ECU is the main unit for controlling the operation of the transfer box. The ECU software was designed in conjunction with Land Rover, Siemens and New Venture Gear. The ECU is connected on the CAN bus and controls the transfer box operation using CAN messages from other ECU's on the network.

The transfer box ECU uses three connectors for all inputs and outputs. The ECU receives one permanent power supply via a 50A fusible link located on the bulkhead, behind the battery, and an ignition supply via fuse 33 in the passenger compartment fusebox. A second feed via the ignition switch position I and fuse 37 in the passenger compartment fusebox, activates the neutral selection function.

The ECU memorizes the position of the actuator when the ignition is switched off. When the ignition is subsequently switched on, the ECU powers the actuator until the lead screw drives the fork and rail assembly against the end stop for the previous range. The ECU then calibrates itself to this position and confirms that the selected range is correct.

The ECU controls the closed loop position sensing system within the actuator and regulates the power supply to the motor to ensure the optimum shift quality is achieved. Using a series of specific software algorithms, the ECU is capable of adjusting the performance of the synchronizer system to produce smooth and effortless shifting, regardless of temperature and vehicle speed, providing the neutral and speed parameters are achieved.

The ECU uses a series of programmed shift maps to control the synchronization speed and ensure that a maximum shift time of 1.2 seconds is achieved.

If the ECU is replaced, TestBook/T4 must be connected to the vehicle and the transfer box ECU self-calibration procedure must be performed. This procedure must also be performed if the actuator and gearbox assembly is replaced.

Default/Limp Home Strategy
If a fault occurs with the transfer box, the transfer box ECU or one of the required input signals, i.e.; road speed signal, the ECU records an error code and the transfer box low range 'mountain' symbol in the instrument pack flashes permanently.

As a default setting, the ECU will attempt to engage high or low range in order to allow the vehicle to be driven to a Land Rover dealer for repair. To ensure a range is engaged, the ignition must be switched off and then on again (timed shift performs this without ignition cycling). This causes the ECU to power the actuator and engage the previously selected range.

Diagnostics
The transfer box ECU can store fault codes which can be retrieved using TestBook/T4 or a diagnostic tool using KW2000* protocol.

The transfer box ECU uses Diagnostic Trouble Codes (DTC) which relate to transfer box electrical faults.

Controller Area Network (CAN) Bus
In the event of a CAN bus failure the following symptoms may be observed:
- Shift from high to low or low to high inoperative
- Instrument pack low range warning lamp inoperative
- Instrument pack transfer box messages in message centre inoperative.