Freelander System Description and Operation
ENGINE MANAGEMENT SYSTEM - SIEMENS
18-4-48 DESCRIPTION AND OPERATION
CAN System
The following CAN messages are used for control of the cruise control system:
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Cruise control status, from the ECM. To advise the interface ECU if the ECM cruise control mode is active or
inactive. Also used by the instrument pack to operate the cruise control warning lamp.
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Road speed, produced by the ABS modulator from ABS sensor inputs. Used by the ECM for monitoring vehicle
speed.
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Accelerator pedal position, from the ECM. Used by the EAT ECU for gear change control.
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Gear lever position, from the EAT ECU. Used by the ECM to ensure the vehicle is in drive for cruise control
operation.
Brake Pedal Sensor
Outputs from the brake pedal sensor are supplied to the ECM to enable the system to detect when the brakes are
applied. The brake pedal sensor is a Hall effect sensor that produces two outputs. Both outputs should be 0 to 2 volts
while the brake pedal is released. When the brake pedal is pressed, the Brake Lamp Switch (BLS) output increases
to between 6 and battery volts, the Brake Test Switch (BTS) output increases to between 10 and battery volts.
ECM
The ECM incorporates a software module and associated components to enable cruise control operation by direct
control of the electric throttle. In addition to controlling the throttle, the software module monitors hardwired and CAN
bus inputs to the ECM and prevents or suspends cruise control operation when the vehicle is not in the correct driving
configuration.