Operation

OPERATION

General

Feed from the positive battery terminal (C0192) is supplied to fusible link 1, fusible link 3, fusible link 8, and fusible 11 (C0632) on an R wire. All are located in the engine compartment fuse box.

Fusible link 8 (C0574) and fusible link 11 (C0570) provide constant battery feeds to the ABS modulator (C0500) on NK and NR wires respectively. The ABS modulator (C0500) is earthed on a pair of B wires.

Fusible link 1 is connected in series with fusible link 2, which is also located in the engine compartment fuse box. Fusible link 2 (C0571) provides a feed to the ignition switch (C0028) on an NR wire. Fusible link 3 (C0571) also provides a feed to the ignition switch (C0028) on an N wire.

When the ignition switch is turned to the 'ignition' position, current flows across the switch (C0028) to fuse 2 of the passenger compartment fuse box (C0588) on an NW wire. When in the 'ignition' position, the ignition switch (C0028) also provides a feed to fuse 7 and fuse 35 of the passenger compartment fuse box on a G wire.

Fuse 2 of the passenger compartment fuse box (C0580) provides an ignition feed to the brake pedal switch (C0075) and the HDC relay (C0574) on G wires. Fuse 35 (C0580) provides an ignition feed to the brake pedal sensor (C0652) on a W wire, and fuse 7 (C0582) provides an ignition feed to the ABS ECU (C0500), also on a W wire.

Wheel Speed Sensors

The ABS ECU (C0500) supplies a feed to all four wheel speed sensors as follows:

To the LH front wheel speed sensor (C0516) on a G wire. To the RH front wheel speed sensor (C0517) on a G wire. To the LH rear wheel speed sensor (C0502) on a W wire. To the RH rear wheel speed sensor (C0503) on a W wire.

The wheel speed sensors provide the ABS ECU with a square wave form signal. By measuring the frequency of the wave form, the ABS ECU can calculate the speed of the road wheel. The sensors provide the ABS ECU (C0500) with wheel speed signals as follows:

From the LH front wheel speed sensor (C0516) on a G wire. From the RH front wheel speed sensor (C0517) on a G wire. From the LH rear wheel speed sensor (C0502) on a W wire. From the RH rear wheel speed sensor (C0503) on a W wire.

If the ABS ECU detects wheel deceleration is too great, it will initiate the ABS. If the ABS ECU detects that wheel speed is greater than vehicle speed, it will initiate ETC. If HDC is operational, the ABS ECU will control vehicle speed at 7 mph (11 km/h) by applying the brakes where necessary. For more information on ABS, ETC, and HDC, refer to the Brakes section of the System Description and Operation Workshop manual.