Code No. P0004: Suction Control Valve Battery Short

OPERATION

The voltage is applied from the engine-ECU connector terminal SCV+ to the suction control valve connector terminal via the power transistor in the engine-ECU.
The voltage is earthed to the engine-ECU connector terminal SCV- from the suction control valve connector terminal.

FUNCTION

The engine-ECU performs duty control over the suction control valve.
The engine-ECU checks whether the amount of current for driving duty is adequate.

TROUBLE JUDGEMENT

Check Conditions

Battery positive voltage is 8 - 16 V
2 seconds later after the ignition switch has been in "ON" position or the engine has started up
The supply pump and injector are being normally controlled.
The fuel injection amount is 4 mm³/st or more.

Judgement Criterion

When the driving duty ratio of the suction control valve is lower than the specified value, the driving current is higher than the specified value.

FAIL-SAFE AND BACKUP FUNCTION

The rail pressure is controlled in the range between 50 and 100 MPa.
The fuel injection amount is restricted (output restriction).
The open angle of the accelerator pedal is restricted.
The throttle valve is closed (fixed opening degree).
The EGR control is stopped (fully closed).
The DPF regeneration is prohibited.

PROBABLE CAUSES

Failed suction control valve
Short circuit in suction control valve circuit or loose connector contact
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check suction control valve itself.

Check suction control valve itself (Refer to ).

Q. Is the check result normal?

	Go to Step 2.

	Replace the suction control valve.

STEP 2. Check of short to power supply in SCV+ line between engine-ECU connector and suction control valve connector.

Q. Is the check result normal?

	Go to Step 3.

	Repair the connector(s) or wiring harness.

STEP 3. Check of short to power supply in SCV- line between engine-ECU connector and suction control valve connector.

Q. Is the check result normal?

	Go to Step 4.

	Repair the connector(s) or wiring harness.

STEP 4. M.U.T.-III diagnosis code

Reconfirmation of diagnosis code.

Q. Is the diagnosis code set?

	Replace the engine-ECU.

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions).