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Hino P0643 Fault Code: ECU Sensor Power Supply 1 Failure (Out Of Range High)

09/12/2025

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Technical Description

Power is supplied to the sensor power supply 1 circuit. (Sensor power supply 3, sensor power supply 4, common rail pressure sensor (main), accelerator sensor 2, engine speed sub sensor).

Description Of Malfunction

High voltage failure of sensor power supply circuit is detected.

DTC Set Condition

DTC Detection Condition:

Starter switch ON.
Battery voltage is in the range of 10 V to 16 V.

Above conditions continue for at least 5 seconds.

Judgment Criteria:

The AC/DC converter input sensor has a power supply voltage no greater than 4.5 V for at least 3 seconds.

Reset Condition

Immediately after normal operation is restored.

Indication, Warning Or System Control Regulation When The DTC Is Set

MIL: OFF
SVS light: OFF

Pre – Inspection Work

Check that the battery voltage is in the normal range.

After – Inspection Work

Clear all past DTCs.
Check that no DTC is stored after test drive.

Possible Causes

Faulty harness (short-circuit in battery power supply of sensor power supply circuit).
Failure in engine ECU sensor power supply or internal circuit.

Inspection Procedure

Troubleshooting Steps

Step 1) Check the power supply of common rail pressure sensor 1.

Set the starter switch to the “LOCK” position.
Disconnect the common rail pressure sensor 1 connector.
Set the starter switch to the “ON” position.
Use the electrical tester to measure the voltage between the terminals of the common rail pressure sensor 1 connector.

MEASUREMENT CONDITIONS

TESTER CONNECTIONS

STANDARD VALUES

Starter switch: ON

Common rail pressure sensor 1 vehicle-side connector

VCC2 – GND2

4.5 – 5.5 V

Do the measurements meet the standard value?

Yes – Go to Step 2.

No – Repair or replace the harness.

Clear all past DTCs. Check that no DTC is detected after test drive.

Step 2) Check the power supply of accelerator sensor 2.

Set the starter switch to the “LOCK” position.
Disconnect the accelerator sensor 2 connector.
Set the starter switch to the “ON” position.
Use the electrical tester to measure the voltage between the terminals of the accelerator sensor 2 connector.

MEASUREMENT CONDITIONS

TESTER CONNECTIONS

STANDARD VALUES

Starter switch: ON

Accelerator sensor 2 vehicle-side connector

VCC2 – GND2

4.5 – 5.5 V

Do the measurements meet the standard value?

Yes – Go to Step 3.

No – Repair or replace the harness.

Clear all past DTCs. Check that no DTC is

detected after test drive.

Step 3) Check the power supply of camshaft position sensor (engine speed sub sensor).

Set the starter switch to the “LOCK” position.
Disconnect the camshaft position sensor (engine speed sub sensor) connector.
Set the starter switch to the “ON” position.
Use the electrical tester to measure the voltage between the terminals of the camshaft position sensor (engine speed sub sensor) connector.

MEASUREMENT CONDITIONS

TESTER CONNECTIONS

STANDARD VALUES

Starter switch: ON

Camshaft position sensor (engine speed sub sensor) vehicle-side connector

MREV – MREG

4.5 – 5.5 V

Do the measurements meet the standard value?

Yes – Go to Step 4.

No – Repair or replace the harness.

Clear all past DTCs. Check that no DTC is detected after test drive.

Step 4) Check the power supply of all sensors.

Set the starter switch to the “LOCK” position.
Connect the signal check harness to the engine ECU.
Set the starter switch to the “ON” position.
Use the electrical tester to measure the resistance between the terminals of the engine ECU (signal check harness).

MEASUREMENT CONDITIONS

TESTER CONNECTIONS

STANDARD VALUES

Starter switch: ON

Engine ECU (signal check

harness)

(+) – (-)

AV2(E33) – AG1(E56)

GVCC(E53) – AG1(E56)

AVC2(V51) – AG1(E56)

4.9 – 5.1 V