Inspection Procedure 25: Power Steering Fluid Pressure Switch System

CONDITION

The battery voltage is applied to the power steering fluid pressure switch terminal from the engine-ECU terminal P/S.

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 in power steering fluid pressure switch circuit or loose connector contact
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Perform voltage measurement at power steering fluid pressure switch connector.

Disconnect connector, and measure at harness side.
Ignition switch: "ON"
Voltage between terminal P/S line and body earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 5.

	Go to Step 2.

STEP 2. Perform voltage measurement at engine-ECU connector.

Measure engine-ECU terminal voltage.
Ignition switch: "ON"
Voltage between terminal P/S and body earth.

OK: System voltage

Q. Is the check result normal?

	Repair or replace the connector(s), or check and repair the harness of open circuit in P/S line between power steering fluid pressure switch connector and engine-ECU connector.

	Go to Step 3.

STEP 3. Check of short to earth in P/S line between power steering fluid pressure switch connector and engine-ECU connector.

Q. Is the check result normal?

	Go to Step 4.

	Repair the connector(s) or wiring harness.

STEP 4. M.U.T.-III data list

Refer to Data List Reference Table .

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 5. Perform voltage measurement at engine-ECU connector.

Measure engine-ECU terminal voltage.
Engine: Idling
Voltage between terminal P/S and earth.

OK:
System voltage (Steering wheel: Stationary)
1 V or less (Steering wheel: Turned)

Q. Is the check result normal?

	Go to Step 4.

	Go to Step 6.

STEP 6. Check of damage in P/S line between power steering fluid pressure switch connector and engine-ECU connector.

Q. Is the check result normal?

	Replace the power steering fluid pressure switch.

	Repair the connector(s) or wiring harness.