ABS (ANTI-LOCK BRAKE SYSTEM)8-932. Check the appearance.3. Check the wire harness.1. Disconnection of the ABS ECU coupler terminal2. Remove the ABS ECU coupler and wheel sensor coupler and check the conductivity, short-circuit to GND and short-circuit to SSR-VCC from the wire harness.• Conductivity of the wire harnessCheck the conductivity between “A”–“B”, and “C”–“D”.• GND short-circuitCheck the short-circuit to GND between “A”–“B”, and “C”–“D”.• Short-circuit between the wire harnessesCheck the short-circuit between “A”–“C”, and “B”–“D”.4. When the items “1” to “4” are normal, replace the wheel sensor.5. Replace the ABS ECU if the condition does not become normal even if the wheel sensor isreplaced.Malfunction code 18 (Missing serration of sensor rotor)1. Missing serration of the rear sensor rotor.• Replace the rear sensor rotor.Malfunction code 21 (Disconnection and short-circuit of hydraulic unit solenoid.)1. Hydraulic unit solenoid coupler• Check if the hydraulic unit solenoid coupler terminal is disconnected. (Refer to "ABS CONNEC-TOR LOCATION CHART" on page 8-75.)2. Hydraulic unit solenoid• Check the front and rear wheel solenoids for continuity → [D-5]• Check the insulation of all solenoid terminals and the negative battery terminal. → [D-5]3. Wire harness (ABS)• Check the hydraulic unit solenoid circuits for continuity. (See the illustration below.)1. ABS ECU2. Front wheel sensor3. Rear wheel sensor4. Blue5. Black6. Yellow/White7. White8. Gray