C0278  DISCONNECTION OF SOLENOID RELAY

1. Set the starter switch to "LOCK", check the ABS solenoid 30A fuse.
   Standard: No abnormality

   

Replace the ABS solenoid fuse.

[2] RELAY CHECK

1. Disconnect the 31 pin connector of the ECU.
2. Measure the resistance between 1st and 24th terminals of the 31 pin connector (chassis harness side).
   Standard: 160-340 Ω
   
   
   　

Go to the item "6".

[2]-3

3. Remove the ABS solenoid relay, measure the resistance between 3rd and 5th terminals of the relay.
   Standard: More than 500 Ω

   
   　

Abnormality of the ABS solenoid relay.

[3] WIRE HARNESS CHECK

1. Disconnect the 24 pin connector of ABS actuator.
2. Measure the resistance between 16th terminal of the 24 pin connector of ABS actuator (chassis harness side) and 2nd terminal of the ABS solenoid relay (socket side).
   Standard: Less than 5 Ω
   
   

　

Abnormality of the wire harness.

[4] RELAY CHECK

1. Remove the ABS solenoid relay, check the continuity between 3rd and 5th terminals of relay when a battery voltage was applied between 1st and 2nd terminals of relay.
   Standard:
   Turning on electricity between 1st and 2nd terminals: It is conducted between 3rd and 5th terminals.
   Not turning on electricity: It is not conducted between 3rd and 5th terminals.
   
   

Abnormality of the ABS solenoid relay.

[5] ECU CHECK

1. Connect all the connector and relay, turn the starter switch to "ON".
2. Measure the voltage between 1st and 2nd terminals of the 31 pin connector of ECU. (Leaving the connector connected with ECU.)
   Standard: 20-28V
   
   

Abnormality of the ECU power supply circuit.

[5]-3

3. Measure the voltage between 24th and 2nd terminals of the 31 pin connector. (Leaving the connector connected with ECU.)
   Standard: Less than 2V
   
   
   　

Abnormality of the ECU power supply circuit.

[5]-4

4. Measure the voltage between 6th terminal of the 22 pin connector and 2nd terminal of the 31 pin connector. (Leaving the connector connected with ECU.)
   Standard: 20-28V
   
   
   　

Abnormality of the ECU power supply circuit.

Normal

1. Turn the starter switch to "LOCK", disconnect the 31 pin connector of ECU.
2. Measure the resistance between 1st terminal of the 31 pin connector of ECU (chassis harness side) and 4th terminal of the ABS solenoid relay (socket side).
   Standard: Less than 5 Ω
   
   

Abnormality of the wire harness.

[6]-3

3. Measure the voltage between 24th terminal of the 31 pin connector of ECU (chassis harness side) and 1st terminal of the ABS solenoid relay (socket side).
   Standard: Less than 5 Ω
   
   

Abnormality of the wire harness.

[7]RELAY CHECK

1. Remove the ABS solenoid relay, measure the resistance between 1st and 2nd terminals.
   Standard: 200-300 Ω

   

Abnormality of the ABS solenoid relay.

Normal.

1. Confirm the DTC C0278 is inactive

   • Start the engine and let it idling condition.
   • Verify the DTC C0278 is inactive.

   

2. DTC Clear

   • Clear the DTC with Hino DX
   • Confirm the same DTC is not reoccurred

   

C0278 is reoccur: Return to first process Other DTC appear: Refer to concerned Trouble shooting

Complete