MALFUNCTION OF DIFFERENTIAL PRESSURE SENSOR [HI]
(DTC CODE P1428 / DIAGNOSIS MONITOR CODE 28)

1. Set the starter key to the "LOCK" position and disconnect the DPR differential pressure sensor connector.
2. Measure resistance between the 2nd and 3rd terminals of the DPR differential pressure sensor connector (component side).

   
   

   
   

   Standard value: 2-15 kΩ

3. Measure resistance between the 1st and 2nd terminals of the DPR differential pressure sensor connector (component side).

Standard value: 2-15 kΩ

NO Fault in DPR differential pressure sensor	YES Proceed to [2] Measuring voltage between terminals

1. Turn the starter key "ON" and measure voltage between the 1st and 3rd terminals of the DPR differential pressure sensor connector (vehicle harness side).

   
   

   Standard value: 4.5-5.5 V

2. Measure voltage between the 2nd and 3rd terminals of the DPR differential pressure sensor connector (vehicle harness side).

Standard value: 4.5-5.5 V

NO Go to [3] Measuring continuity between terminals.	YES Improper engagement of connector

1. Set the starter key to the "LOCK" position and connect the signal check harness.
2. Disconnect the signal check harness connectors from the ECU and measure resistance between the terminals V70 and V71.

   

   ECU terminal No.	Description of terminal
   V70	Differential pressure sensor SIG
   V71	Sensor +B

   Standard value: ∞ Ω

3. Measure resistance between the terminals V 70 and V 80.

ECU terminal No.	Description of terminal
V70	Sensor SIG
V80	Sensor GND

Standard value: ∞ Ω

NO Improper engagement of connector or faulty harness	YES Proceed to [4] Measuring resistance between terminals

1. Disconnect the signal check harness connectors from the vehicle harness.
2. Connect the signal check harness connectors to the ECU and measure resistance between the terminals V70 and V71.



 

ECU terminal No.	Description of terminal
V70	Differential pressure sensor SIG
V71	Sensor +B

Standard value: 200-250 kΩ

NO Fault in engine ECU	YES Proceed to [5] Measuring voltage between terminals

1. Turn the starter key "ON" and measure voltage between the terminals V71 and V80.

   

   ECU terminal No.	Description of terminal
   V71	Sensor +B
   V80	Sensor GND

   Standard value: 4.5-5.5 V

    

2. Measure voltage between the terminals V70 and V80.

ECU terminal No.	Description of terminal
V70	Sensor SIG
V80	Sensor GND

Standard value: 4.5-5.5 V

NO Fault in engine ECU	YES Use HINO-DX to delete past malfunctions and then output diagnosis codes again.

1. Confirm the DTC P1428 is inactive

   • Start the engine and let it idling condition.
   • Verify the DTC P1428 is inactive.

   

2. DTC Clear

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

   

P1428 is reoccur: Return to first process Other DTC appear: Refer to concerned Trouble shooting

Complete