Ignition key interlock (where fitted) (Body control unit)

Ignition key interlock (where fitted)

On automatic gearbox models, the ignition key interlock solenoid prevents removal of the ignition key from the ignition switch when the transmission gear selector is not in the Park position. The logic control operation for this is performed by the BCU.

Transfer box interlock (where fitted)

On automatic gearbox models, a transfer box interlock solenoid is controlled by the IDM to prevent transfer box shift lever being moved out of high or low range unless certain conditions have been satisfied. The IDM controls the operation of the transfer box relay which is located in the passenger compartment fuse box. TRANSFER BOX - LT230SE, DESCRIPTION AND OPERATION, Description.

Gear position switch

A gear position switch is located on the automatic gearbox and is used to inform the BCU of the gear selector lever position. The BCU has four sensing inputs from the gear position switch contacts W, X, Y, Z, which are used to determine the gearbox drive status at any particular instance. The BCU gives an output corresponding to the gearbox status derived from the gear position switch inputs. The logic states defining the gear selector positions are listed in the table below, where Z1, Z2, Z3 and Z4 represent intermediate states which exist as the selector lever position is changed:

The existence of an intermediate state causes a fault code to be detected by the BCU. To reduce the chances of the fault condition occurring while changing selector lever position, the inputs are debounced and only considered valid when they have existed for at least 33 ms.

Transmission neutral selector

The transmission neutral sensor provides an earth signal to the BCU when the transfer box is in neutral. The earth signal causes the BCU to operate an audible warning when the transfer box is in neutral with the ignition switched on. TRANSFER BOX - LT230SE, DESCRIPTION AND OPERATION, Description.