DTC P0554: Power Steering Pressure Switch Circuit Intermittent

CIRCUIT OPERATION

A battery positive voltage is applied to the power steering pressure switch output terminal (terminal No. 1) from the ECM (terminal No. 58) via the resistor in the ECM.

TECHNICAL DESCRIPTION

The power steering pressure switch converts the existence of a power steering load into a high/low voltage, and inputs it into the ECM.
When the steering wheel is turned, hydraulic pressure rises. The power steering pressure switch closes, and the applied battery positive voltage will be grounded. With this, the power steering pressure switch output voltage will fluctuate between 0 and 12 volts.
While driving with the steering wheel held straight, the power steering pressure switch turns "OFF".
The ECM checks whether the power steering pressure switch turns "OFF" or "ON" during driving.

DESCRIPTIONS OF MONITOR METHODS

MONITOR EXECUTION

MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)

Not applicable

Sensor (The sensor below is determined to be normal)

Engine coolant temperature sensor

DTC SET CONDITIONS

Logic Flow Chart

Check Conditions

Engine coolant temperature is more than 65°C (149°F).
Vehicle speed is more than 50 km/h (31 mph).

Judgement Criterion

The ON/OFF frequency of a power steering pressure switch is more than 10 Hz for 20 seconds.

FAIL-SAFE AND BACKUP FUNCTION

None

OBD-II DRIVE CYCLE PATTERN

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)

Power steering pressure switch failed.
Incorrect power steering fluid level.
Incorrect oil pump pressure.
Harness damage in power steering pressure switch circuit, or connector damage.
ECM failed.

DIAGNOSIS

Required Special Tools:

MB991958: Scan Tool (M.U.T.-III Sub Assembly)

MB991824: V.C.I.
MB991827: USB Cable
MB991910: Main Harness A

STEP 1. Using scan tool MB991958, check data list item 83: Power Steering Pressure Switch.

caution

To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

(1)Connect scan tool MB991958 to the data link connector.
(2)Start the engine and run at idle.
(3)Set scan tool MB991958 to the data reading mode for item 83, Power Steering Pressure Switch.

If the steering wheel is not turned while idling, "OFF" will be displayed.
If the steering wheel is turned while idling, "ON" will be displayed.

(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the switch operating properly?

It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions

Go to Step 2.

STEP 2. Check the power steering fluid level.

Refer to GROUP 37, On-vehicle Service - Fluid Level Check

Q. Are there any abnormalities?

	Repair it. Then go to Step 7.

	Go to Step 3.

STEP 3. Check the power steering pressure switch.

Refer to GROUP 37, On-vehicle Service - Power Steering Pressure Switch Check

Q. Are there any abnormalities?

	Replace the power steering pressure switch. Then go to Step 7.

	Go to Step 4.

STEP 4. Check the oil pump pressure.

Refer to GROUP 37, On-vehicle Service - Oil Pump Pressure Test

Q. Are there any abnormalities?

	Repair it. Then go to Step 7.

	Go to Step 5.

STEP 5. Check harness connector B-17 at power steering pressure switch and harness connector B-108 at ECM for damage.

Q. Are the harness connectors in good condition?

	Go to Step 6.

	Repair or replace them. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 7.

STEP 6. Check for harness damage between power steering pressure switch connector B-17 (terminal No. 1) and ECM connector B-108 (terminal No. 58).

Q. Is the harness wire in good condition?

	Replace the ECM. When the ECM is replaced, register the ID code. Refer to GROUP 42B, Diagnosis - ID Code Registration Necessity Judgment Table <Vehicles with KOS> or GROUP 42C, Diagnosis - ID Codes Registration Judgment Table <Vehicles with WCM> . Then go to Step 7.

	Repair it. Then go to Step 7.

STEP 7. Test the OBD-II drive cycle.

(1)Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 16

(2)Check the diagnostic trouble code (DTC).

Q. Is DTC P0554 set?

	Retry the troubleshooting.

	The inspection is complete.