Inspection Procedure 23: Power Steering Fluid Pressure Switch System










CONDITION



  • The battery voltage is applied to the power steering fluid pressure switch (terminal No. 1) from the engine-ECU (terminal No. 58).

FUNCTION



  • It is detected whether a load is applied on the power steering fluid pump by steering or not, and the signal is inputted to the engine-ECU. When the power steering fluid pressure switch "ON" signal (a large load on the power steering fluid pump) is inputted, the engine-ECU provides the idle-up control.

PROBABLE CAUSES



  • Failed power steering fluid pressure switch
  • Open/short circuit or harness damage in power steering fluid pressure switch circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE


STEP 1. Connector check: B-36 power steering fluid pressure switch connector


Q. Is the check result normal?

Go to Step 2 .
Repair or replace the connector.

STEP 2. Perform voltage measurement at B-36 power steering fluid pressure switch connector.



  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 1 and earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 8 .
Go to Step 3 .

STEP 3. Perform voltage measurement at B-29 engine-ECU connector.



  • Measure engine-ECU terminal voltage.
  • Ignition switch: ON
  • Voltage between terminal No. 58 and earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 4 .
Go to Step 5 .

STEP 4. Connector check: B-29 engine-ECU connector


Q. Is the check result normal?


    Check and repair harness between B-36 (terminal No. 1) power steering fluid pressure switch connector and B-29 (terminal No. 58) engine-ECU connector.

    • Check output line for open circuit.
Repair or replace the connector.

STEP 5. Connector check: B-29 engine-ECU connector


Q. Is the check result normal?

Go to Step 6 .
Repair or replace the connector.

STEP 6. Check harness between B-36 (terminal No. 1) power steering fluid pressure switch connector and B-29 (terminal No. 58) engine-ECU connector.



  • Check output line for short circuit.

Q. Is the check result normal?

Go to Step 7 .
Repair the damaged harness wire.

STEP 7. M.U.T.-III data list



  • Refer to Data List Reference Table .

  1. Item 83: Power steering fluid pressure switch

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.

STEP 8. Perform voltage measurement at B-29 engine-ECU connector.



  • Measure engine-ECU terminal voltage.
  • Engine: Idling
  • Voltage between terminal No. 58 and earth.
OK:
    System voltage (Steering wheel: Stationary)
    1 V or less (Steering wheel: Turned)

Q. Is the check result normal?

Go to Step 11 .
Go to Step 9 .

STEP 9. Connector check: B-29 engine-ECU connector


Q. Is the check result normal?

Go to Step 10 .
Repair or replace the connector.

STEP 10. Check harness between B-36 (terminal No. 1) power steering fluid pressure switch connector and B-29 (terminal No. 58) engine-ECU connector.



  • Check output line for damage.

Q. Is the check result normal?

Replace the power steering fluid pressure switch.
Repair the damaged harness wire.

STEP 11. Connector check: B-29 engine-ECU connector


Q. Is the check result normal?

Go to Step 7 .
Repair or replace the connector.