P0551 – Power Steering Fluid Pressure Switch System MMC L200 IV

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OPERATION

The battery voltage is applied to the power steering pressure switch (terminal No. 1) from the engine-ECU (terminal No. 127)

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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.

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TROUBLE JUDGMENT

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

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

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PROBABLE CAUSES

Failed power steering fluid pressure switch

Short circuit in power steering fluid pressure switch circuit or loose connector contact

Failed engine-ECU

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DIAGNOSIS PROCEDURE

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

Item 75: Power steering fluid pressure switch

Q. Is the check result normal?

STEP 2. Connector check: A-134 power steering pressure switch connector

Q. Is the check result normal?

STEP 3. Check power steering pressure switch itself.

Disconnect A-134 power steering fluid pressure switch connector.

Continuity between terminal No.1 and earth.

Q. Is the check result normal?

STEP 4. Check at A-134 power steering fluid pressure switch connector.

Disconnect connector, and measure at harness side.

Ignition switch: ON

Voltage between terminal No.1 and earth.

Q. Is the check result normal?

STEP 5. Connector check: C-103 engine-ECU connector

Q. Is the check result normal?

STEP 6. Check harness between C-103 (terminal No. 127) engine-ECU connector and A-134 (terminal No. 1) power steering fluid pressure switch connector.

Check output line for short circuit.

Q. Is the check result normal?

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

Item 75: Power steering fluid pressure switch

Q. Is the check result normal?