Freelander JATCO Automatic Gearbox: Selector & Inhibitor Switch
AUTOMATIC GEARBOX - JATCO
DESCRIPTION AND OPERATION
44-27
Selector and Inhibitor Switch
The selector and inhibitor switch is located on the selector shaft on top of the gearbox and connected to the main
harness by a 10 pin connector (C0244).
While the ignition is on, the selector and inhibitor switch receives a battery voltage power feed from the main relay. In
some markets, in order to illuminate the LED module whenever the key is in the ignition switch, the selector and
inhibitor switch also receives a battery voltage power feed from an illumination relay installed behind the centre
console.
Where fitted, operation of the illumination relay is controlled by the passive coil on the ignition switch. When the key
is installed in the ignition switch the illumination relay energises to connect the power feed to the selector and inhibitor
switch. When the main relay is energised by the ECM, the illumination relay de-energises and the power feed to the
selector and inhibitor switch is taken from the main relay.
The EAT ECU and the LED module are provided with a voltage output from the selector and inhibitor switch that
corresponds with the gear position the driver has selected. Seven sets of contacts in the selector and inhibitor switch
which are operated by the selector shaft. Each set of contacts corresponds to one of the seven selector lever positions
(PRND421). Only one set of contacts will supply battery voltage to the EAT ECU and the LED module at any one time.
The EAT ECU monitors the switch outputs every 10 ms.
A pair of contacts are provided for the crank inhibit circuit. The contacts are only closed when the selector lever is in
the 'P' and 'N' positions.
The two contacts are wired in series with the immobilisation ECU. When the selector lever is in any position other than
'P' or 'N', the feed from the ignition switch to the immobilisation ECU is broken by the open contacts, preventing starter
motor operation.
In the event of a selector and inhibitor switch signal failure, any of the following symptoms may be observed:
l
Upshift to 5th gear inoperative
l
Torque converter lock-up inoperative
l
Torque reduction request from the EAT ECU to the ECM inoperative
l
Cranking disabled if fault is on the two inhibitor switch contacts.