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


OPERATION



  • Power is supplied to the variable geometry control solenoid valve (terminal No. 2) from the engine control relay (terminal No. 2).
  • The engine-ECU (terminal No. 17) makes the power transistor in the unit be in "ON" position, and that makes currents go on the variable geometry control solenoid valve (terminal No. 1).

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 JUDGMENT


Check Conditions
  • Battery positive voltage is 8 - 16 V.
  • 2 seconds later after the engine has started up.
Judgment 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.
  • The AS&G 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. Connector check: B-18 variable geometry control solenoid valve connector, B-09 engine-ECU connector

Q. Are the check results normal?
Go to Step 2 .
Repair or replace the connector.

STEP 2. Check harness between B-18 (terminal No. 1) variable geometry control solenoid valve connector and B-09 (terminal No. 17) engine-ECU connector.

  • Check output line for short circuit.

Q. Is the check result normal?
Go to Step 3 .
Repair the damaged harness wire.

STEP 3. 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 ).