Code No. P0551: Power Steering Fluid Pressure Switch System

OPERATION

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

TROUBLE JUDGEMENT

Check Condition

Within 5 seconds after the ignition switch is in the "OFF" position.

Judgement Criterion

For 2 seconds, the power steering fluid pressure switch is in the "ON" position and the engine continuously stops.

PROBABLE CAUSES

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

DIAGNOSIS PROCEDURE

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

Refer to Data List Reference Table .

Item 75: 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).

	Go to Step 2.

STEP 2. Perform resistance measurement at power steering fluid pressure switch connector.

Disconnect connector, and measure at harness side.
Resistance between terminal P/S line and body earth.

OK: No continuity

Q. Is the check result normal?

	Replace the power steering fluid pressure switch.

	Go to Step 3.

STEP 3. 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 4.

STEP 4. Check harness in P/S line between engine-ECU connector and power steering fluid pressure switch connector.

Q. Is the check result normal?

	Go to Step 5.

	Repair the connector(s) or wiring harness.

STEP 5. M.U.T.-III data list.

Refer to Data List Reference Table .

Item 75: 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.