Range Rover P38
19
FUEL SYSTEM
NEW RANGE ROVER
30
DESCRIPTION AND OPERATION
Inertia Fuel Shut-off (IFS) Switch
The inertia switch isolates the power supply to the fuel
pump in the event of sudden deceleration, as
encountered during an accident. The inertia switch is
located in the right hand side footwell behind an
access flap. It is reset by depressing the central
plunger at the top of the switch.
Electronic Automatic Gearbox Interface - up to
99MY
Engine Torque Signal
The engine torque signal is calculated by the GEMS
ECM and output to the gearbox ECU in a 12 volt
PWM signal format. Warm up status of GEMS is
passed on start-up for OBDII purposes.
Throttle Angle Signal
The throttle signal is output by the GEMS ECM to the
gearbox ECU in a 12 volt PWM signal format. The
signal is used to calculate when a gear change is
necessary. If a fault occurs with this signal, then the
gearbox ECU assumes a default throttle angle. The
signal is also used to indicate engine temperature at
starting.
Ignition Retard (Torque Reduction)
The gearbox ECU calculates the optimum shift point
and in order to produce a smooth gear change, sends
a torque reduction signal to the GEMS ECM which
retards the ignition so reducing the engine torque to
allow a smooth shift.
Engine Speed Signal
The engine speed signal is output to the gearbox ECU
via the Body electronic control module (BeCM). The
signal comprises a 12 volt square wave with 4 pulses
for every engine revolution.
The following fault modes are possible:
•
Harness wiring or connector faulty
•
Power up problems
•
Faulty gearbox ECU
Fault codes:
•
P1775 - Gearbox has signalled a fault condition
to the ECM
•
P1776 - Gearbox ignition retard request duration
fault
•
P1777 - Gearbox ignition retard request line fault
See AUTOMATIC GEARBOX, Description
and operation.