Electronic Automatic Gearbox Interface (Range Rover Only)

Electronic Automatic Gearbox Interface (Range Rover Only) Description

1. Fault codes:
Gearbox has signalled a fault condition to the ECM. (Range Rover only) P1775
Gearbox ignition retard request duration fault (Range Rover only) P1776
Gearbox ignition retard request line fault (Range Rover only) P1777

Engine Torque Signal
The engine torque signal is calculated by the GEMS ECM and output to the gearbox ECM in a 12 volt PWM signal format. Warm up status of GEMS is passed on start-up for OBDII purposes.

Throttle Angle Signal
Once again, a signal produced and output by the GEMS Module directly to the gearbox ECM (in a 12 volt PWM signal format). This signal is used with the other two signals to calculate when a gear change is necessary. If a fault occurs with this signal then the TCU assumes a default throttle angle. Also used to indicate engine temperature at starting.

Ignition Retard (Torque Reduction)
The gearbox 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 by the GEMS Module to the gearbox ECM via the BeCM.
The signal comprises a 12 volt square wave with 4 pulses for every engine revolution.