Code No. C0047: Brake Vacuum Sensor Circuit


OPERATION



  • The power voltage is supplied to the brake vacuum sensor (terminal No. 3) from the AS&G-ECU (terminal No. 7).
  • The sensor signal is inputted to the AS&G-ECU (terminal No. 9) from the brake vacuum sensor (terminal No. 2).
  • The brake vacuum sensor (terminal No. 1) is earthed to the AS&G-ECU (terminal No. 2).

FUNCTION



  • The brake vacuum sensor converts the vacuum pressure in the brake booster into a voltage and inputs the signal to the AS&G-ECU.
  • In response to the signal, the AS&G-ECU controls the AS&G system.

TROUBLE JUDGMENT


Check Condition
  • 2 seconds later after the ignition switch has been in "ON" position or the engine has started up.
Judgement Criterion
  • The brake vacuum sensor output voltage is less than 0.3 V for 2 seconds.


  • The brake vacuum sensor output voltage is more than 4.8 V for 2 seconds.

FAIL-SAFE AND BACKUP FUNCTION



  • In the normal operation, the auto stop is prohibited. If the malfunction is detected during the auto stop, carry out the forcible auto start.

PROBABLE CAUSES



  • Open/short circuit or harness damage in brake vacuum sensor circuit or loose connector contact
  • Failed brake vacuum sensor
  • Failed AS&G-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: A-14 brake vacuum sensor connector

Q. Is the check result normal?
Go to Step 2.
Repair or replace the connector.

STEP 2. Perform voltage measurement at A-14 brake vacuum sensor connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 3 and earth.
OK: 4.9 - 5.1 V

Q. Is the check result normal?
Go to Step 6.
Go to Step 3.

STEP 3. Connector check: C-11 AS&G-ECU connector

Q. Is the check result normal?
Go to Step 4.
Repair or replace the connector.

STEP 4. Check harness between C-11 (terminal No. 7) AS&G-ECU connector and A-14 (terminal No. 3) brake vacuum sensor connector.

  • Check power supply line for open/short circuit.

Q. Is the check result normal?
Go to Step 5.
Repair the damaged harness wire.

STEP 5. M.U.T.-III diagnosis code

  • Reconfirmation of the diagnosis code.

Q. Is the diagnosis code set?
Replace the AS&G-ECU.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 6. Connector check: C-11 AS&G-ECU connector

Q. Is the check result normal?
Go to Step 7.
Repair or replace the connector.

STEP 7. Check harness between C-11 (terminal No. 7) AS&G-ECU connector and A-14 (terminal No. 3) brake vacuum sensor connector.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 8.
Repair the damaged harness wire.

STEP 8. Check harness between C-11 (terminal No. 9) AS&G-ECU connector and A-14 (terminal No. 2) brake vacuum sensor connector.

  • Check output line for open/short circuit and damage.

Q. Is the check result normal?
Go to Step 9.
Repair the damaged harness wire.

STEP 9. Check harness between C-11 (terminal No. 2) AS&G-ECU connector and A-14 (terminal No. 1) brake vacuum sensor connector.

  • Check earthing line for open/short circuit and damage.

Q. Is the check result normal?
Go to Step 10.
Repair the damaged harness wire.

STEP 10. M.U.T.-III diagnosis code

  • Reconfirmation of the diagnosis code.

Q. Is the diagnosis code set?
Go to Step 11.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 11. Replace the brake vacuum sensor.

  • After replacing the brake vacuum sensor, reconfirm whether the diagnosis code is set.

Q. Is the diagnosis code set?
Replace the AS&G-ECU.
Check end.