Ignition and Shift Interlock Operation (Description and operation) (page 3 of 3)

With the relay contacts closed, a feed from fuse 21 in the passenger compartment fusebox flows through the relay contacts and from the fusebox to the shift interlock solenoid on a LGP wire, energising the solenoid. The shift interlock solenoid is connected to earth header C0552 LHD/C0708 RHD on a B wire.

With the shift interlock solenoid energised, the transmission selector can be moved from the PARK position. When the brake pedal is released, the feed to the BCU is removed and the shift interlock solenoid is de-energised. The locking mechanism controlled by the solenoid will lock the transmission selector once it is returned to the park position.

Automatic transmission selector A starter/ inhibitor/ reverse lights switch is located on the gearbox and is used to inform related components of the gear selector position. The connection used on this circuit is on an NP wire from the switch to pin C0663-10 on the BCU and signals the BCU of PARK and NEUTRAL selector positions.

Transmission neutral sensor 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 to warn of the transfer box in neutral when the ignition is on.

The sensor is connected on a BK wire from pin C0662-15 on the BCU. The sensor is connected on a B wire, via header C1002 to earth header C0552.

Transfer gearbox interlock solenoid When the BCU senses that the ignition key is removed from the ignition switch, it signals the IDM via the serial data bus. The IDM then grants an earth path for the coil of the transfer box relay in the passenger compartment fusebox, energising the relay coil and closing the relay contacts.

With the contacts closed, a feed from fuse 21 in the passenger compartment fusebox passes through the relay and is connected from the fusebox on an RU wire, via header C0293, to the transfer gearbox interlock solenoid. The solenoid energises and is connected by a B wire to earth header C0552. This prevents neutral being selected locking the transfer gearbox in high or low. A diode is located in the feed to the solenoid from splice joint A77 on an RU wire and from the diode to splice SJ2 on a B wire. The diode prevents residual current causing the solenoid to ’stick’ in the energised position.