Code No. P0048: Variable Geometry Control Solenoid Valve Circuit High Input

OPERATION

Power is supplied to the variable geometry control solenoid valve connector terminal from the engine control relay connector terminal.
The engine-ECU connector terminal VGT makes the power transistor in the unit be in "ON" position, and that makes currents go on the variable geometry control solenoid valve connector terminal.

FUNCTION

The variable geometry control solenoid valve controls the vacuum pressure introduced into the variable geometry actuator, using the signal from the engine-ECU. This allows the boost pressure to be adequate for the driving conditions.

TROUBLE JUDGEMENT

Check Conditions

Battery positive voltage is 8 - 16 V.
2 seconds later after the engine has started up.

Judgement Criterion

Variable geometry control solenoid valve output voltage is 4.5 V or more (driving current is abnormally high).

FAIL-SAFE AND BACKUP FUNCTION

The fuel injection amount is restricted (output restriction).
The open angle of the accelerator pedal is restricted.
The throttle valve is opened (electrical discontinuity).
The EGR control is stopped (fully closed).
The DPF regeneration is prohibited.
The turbocharger control is prohibited.

PROBABLE CAUSES

Short circuit in variable geometry control solenoid valve circuit or loose connector contact
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check of short to power supply in VGT line between engine-ECU connector and variable geometry control solenoid valve connector.

Q. Is the check result normal?

	Go to Step 2.

	Repair the connector(s) or wiring harness.

STEP 2. M.U.T.-III diagnosis code

Reconfirmation of diagnosis code.

Q. Is 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).