COMMUNICATION BLACKOUT [VNT ACTUATOR]
(DTC CODE U1123 / DIAGNOSIS MONITOR CODE 8)

1. Inspect an actuator relay.
   

   Standard: No abnormality

NO Fault in actuator relay. Check the power supply circuit.	YES Proceed to [2] Measuring voltage between terminals

1. Set the starter key to the "LOCK" position and connect the signal check harness.
2. Disconnect the VNT ECU connector.
3. Turn the starter key "ON" and measure voltage between the 13th and 14th terminals of the VNT ECU connector (vehicle harness side).

    

   

   Standard value: 19 V or more

NO Faulty harness

YES Proceed to [3] Measuring resistance between terminals

1. Measure resistance between the terminals of the signal check harness and of the VNT ECU connector (vehicle harness side) as listed below.

    

Signal check harness	VNT ECU
V86	15
V87	16

 

ECU terminal No.	Description of terminal
V86	CANH
V87	CANL

Standard value: 2 Ω or less

NO Faulty harness

YES Fault in VNT ECU

1. Confirm the DTC U1123 is inactive

   • Start the engine and let it idling condition.
   • Verify the DTC U1123 is inactive.

   

2. DTC Clear

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

   

U1123 is reoccur: Return to first process Other DTC appear: Refer to concerned Trouble shooting

Complete