Anti-Lock Braking System (ABS)

ANTI-LOCK BRAKING SYSTEM (ABS)

DESCRIPTION

General
New Range Rover is equipped with Dynamic Stability Control (DSC) for enhanced braking and stability control. Functions of the DSC include:
^ Hill Decent Control (HDC).
^ Electronic traction control (ETC).
^ Anti-lock Braking System (ABS).

The DSC system for New Range Rover provides all of the following functions and features:
^ Optimized traction under all driving conditions.
^ Optimized directional control (Longitudinal Stability).
^ Lateral stability (Correction for over steer/under steer).
^ Corner Braking Control (CBC).
^ Emergency Brake Assist (EBA).
^ Electronic Brake Force Distribution (EBD).

OPERATION

Power Distribution
Feed from the positive battery terminal (C0192) is supplied to the following on R wires:
^ Fusible link 2 (C0632) - V8 vehicles only.
^ Maxi fuse 63 (C0632).
^ Fuse 13 (C0632).
^ Fuse 53 (C0632).
^ Fuse 55 (C0632).

Maxi fuse 63 (C0580) and fuse 55 (C0583) provide constant battery feeds to the ABS ECU (C0506) on R and RB wires respectively. The ABS ECU is earthed on a pair of N wires. Fuse 13 (0586) provides a constant battery feed to the steering angle sensor (C0862) on an RG
wire.

Fuse 53 (C0583) provides a constant battery feed to the ignition switch (C0028 on V8 vehicles) on an R wire. When the ignition switch is turned to the 'auxiliary' position, current flows across the switch (C0028 on V8 vehicles) to fuse 37 of the passenger compartment fuse box (C0585) on a PB wire. Fuse 37 (C0587) provides an auxiliary ignition feed to the Dynamic Stability Control (DSC) switch (C0700), located on the center console, on a GBY wire.

V8
Fusible link 2 (C0632) provides a constant battery feed to the ECM relay (C1895) on an R wire. Operation of the ECM relay (C1895) is controlled by the ECM (C0604) on an N wire. The energized ECM relay (C 1895) provides a feed to fuse 5 1 of the passenger compartment fuse box (C0584) on an RW wire. Fuse 51 (C0584) is connected to the ABS ECU (C0506) and the steering angle sensor (C0862) by a pair of RW wires.

ABS
Wheel Speed Sensors
The ABS ECU (C0506) provides a feed to all four wheel speed sensors as follows:
^ To the LH front wheel speed sensor (C0516) on an R wire.
^ To the RH front wheel speed sensor (C0517) on a Y wire.
^ The LH rear wheel speed sensor (C0502) on a W wire.
^ To the RH rear wheel speed sensor (C0503) on a G wire.

The wheel speed sensors are hall effect sensors, and provide the ABS ECU with a square wave form signal. This signal rises and falls between approximately 2.5V and 0.75V. By measuring the frequency of the waveform, the ABS ECU can calculate the speed of the road wheel. The sensors provide the ABS ECU (C0506) with a wheel speed signal as follows:
^ From the LH front wheel speed sensor (C0516) on a UR wire.
^ From the RH front wheel speed sensor (C0517) on a UY wire.
^ From the LH rear wheel speed sensor (C0502) on a UW wire.
^ From the RH rear wheel speed sensor (C0503) on a UG wire.

DSC
DSC Switch
DSC is active as soon as the ignition switch is turned to the 'ignition' position. DSC can be switched off by pressing the non-latching master switch located on the center console. When the ABS ECU (C0506) receives a momentary feed from the DSC switch (C0700) on a BY wire, it suspends DSC operation. Pressing the switch a second time reinstates DSC.

Steering Angle Sensor
The steering angle sensor (C0862) receives a constant battery feed from fuse 13 of the passenger compartment fuse box (C0586) on an RG wire, and a feed from the energized ECM relay (C1895) via fuse 51 of the passenger compartment fuse box (C0584) on an RW wire. The sensor (C0862) is earthed on an NB wire.

The steering angle sensor (C0862) transmits steering angle and rate of steering messages via the Can bus on YN (low) and YB (high) wires. These signals are created by two potentiometers located within the sensor. The ABS ECU uses these messages to enable the DSC system control lateral stability.

Brake Fluid Level Warning Switch
If the brake fluid level is below the minimum level, DSC operation is suspended. The ABS ECU (C0506) monitors the condition of the brake fluid level switch (C0026) via an NGY wire.

HDC
The HDC switch (C0365) is mounted on the side of the gear selector lever, and is provided an auxiliary ignition feed from fuse 35 of the passenger compartment fuse box (C0587) on a GBY wire. The ABS ECU (C0506) monitors the condition of the HDC switch (C0365) via a BG wire.

EBA
Brake Pedal Switch
The brake pedal switch (C0075) is provided an auxiliary ignition feed from fuse 9 of the passenger compartment fuse box (C0587) on a PY wire. The ABS ECU (C0506) monitors the condition of the brake pedal switch (C0075) on a UR wire to enable it to operate its Emergency Brake Assist (EBA) function.

Diagnostic Socket
The diagnostic socket is located behind an access panel on the drivers side of the fascia. The ABS ECU (C0506) and the steering angle sensor (C0862) can be interrogated by T4 via the K line bus on WP wires.