Code No. P0192: Rail Pressure Sensor Circuit Low Input


OPERATION



  • A power voltage of 5 V is applied to the rail pressure sensor power terminal (terminal No. 1) from the engine-ECU (terminal No. 70) and earthed to the engine-ECU (terminal No. 88) from the rail pressure sensor (terminal No. 3).
  • The sensor signal is inputted to the engine-ECU (terminal No. 64) from the rail pressure sensor output terminal (terminal No. 2).

FUNCTION



  • The rail pressure sensor converts the rail pressure into a voltage signal and inputs the signal to the engine-ECU.
  • In response to the signal, the engine-ECU corrects the fuel injection quantity.

TROUBLE JUDGMENT


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.
Judgment Criterion
  • The rail pressure sensor output voltage is 0.70 V or less.

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.
  • The AS&G control is prohibited.

PROBABLE CAUSES



  • Failed rail pressure sensor
  • Open/short circuit or harness damage in rail pressure sensor circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list

  • Data list reference table (Refer to ).

  1. Item 63: Rail pressure sensor

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Go to Step 2 .

STEP 2. Connector check: B-01 rail pressure sensor connector and B-09 engine-ECU connector

Q. Are the check results normal?
Go to Step 3 .
Repair or replace the connector.

STEP 3. Perform resistance measurement at B-01 fuel pressure sensor connector.

  • Disconnect connector, and measure at harness side.
  • Resistance between terminal No. 2 and earth.
OK: No continuity

Q. Is the check result normal?
Go to Step 5 .
Go to Step 4 .

STEP 4. Check harness between B-01 (terminal No. 2) electronic-controlled throttle valve connector and B-09 (terminal No. 64) engine-ECU connector.

  • Check output line for short circuit.

Q. Is the check result normal?
Go to Step 6 .
Repair the damaged harness wire.

STEP 5. Voltage measurement at B-01 rail pressure sensor connector.

  • Disconnect connector, and measure at sensor side.
  • With the special tool test harness (MB991658) bridge only the mating terminals of No. 1 and No. 3 of the disconnected connector.
  • Ignition switch: ON
  • Voltage between terminal No. 2 and earth.
OK: 0.85 V or more

Q. Is the check result normal?
Go to Step 6 .
Replace the rail pressure sensor.

STEP 6. M.U.T.-III data list

  • Data list reference table (Refer to ).

  1. Item 63: Rail pressure sensor

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Replace the engine-ECU.