Mitsubishi Lancer Evolution X. Manual - part 367

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

13A-533

STEP 10. Check harness connector B-09 at ECM for 
damage. 
Q: Is the harness connector in good condition? 

YES : Go to Step 11.
NO :  Repair or replace it. Refer to GROUP 00E, Harness 

Connector Inspection 

P.00E-2

. Then go to Step 13.

STEP 11. Check for harness damage between power 
steering pressure switch connector B-19 (terminal No. 1) 
and ECM connector B-09 (terminal No. 58). 
Q: Is the harness wire in good condition? 

YES : Go to Step 12.
NO :  Repair it. Then go to Step 13.

STEP 12. Replace the power steering pressure switch. 
(1) Replace the power steering pressure switch. 
(2) Check the trouble symptoms. 
(3) Read in the diagnostic trouble code (DTC). 
Q: Is DTC P0551 set?

YES : Replace the ECM. When the ECM is replaced, 

register the ID code. Refer to GROUP 42B, ID Code 
Registration Necessity Judgment Table <Vehicles 
with KOS> 

P.42B-11

 or GROUP 42C, ID Codes 

Registration Judgment Table <Vehicles with WCM> 

P.42C-9

. Then go to Step 13.

NO :  Go to Step 13.

STEP 13. Using scan tool MB991958, check data list item 
83: Power Steering Pressure Switch. 
(1) Start the engine and run at idle. 
(2) 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. 

(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the switch operating properly?

YES : The inspection is complete.
NO :  Retry the troubleshooting.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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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.

AK704283

1

2

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1

POWER STEERING PRESSURE SWITCH CIRCUIT

POWER STEERING
PRESSURE SWITCH

B-09

B-19

AB

1

58

OFF

ON

ENGINE
CONTROL
MODULE

BLA

CK-WHITE

AK704227

Connector: B-09

ECM

B-09 (GR)

AB

AK704284AB

Power steering
pressure switch

Connector: B-19

B-19

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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MULTIPORT FUEL INJECTION (MFI)

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• 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 fluc-
tuate 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 driv-
ing.

.

DESCRIPTIONS OF MONITOR METHODS

Power steering pressure switch changes from off to 

on more than 10 times for 1 second.

.

MONITOR EXECUTION

Continuous

.

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

.

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

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DTC SET CONDITIONS
Logic Flow Chart

.

Check Conditions

• Engine coolant temperature is higher than 65° C 

(149° F).

• Vehicle speed is 50 km/h (31 mph) or higher.

Judgement Criterion

• The ON/OFF frequency of a power steering pres-

sure switch is 10 Hz or more for 20 seconds.

.

FAIL-SAFE AND BACKUP FUNCTION

• None

.

OBD-II DRIVE CYCLE PATTERN

Refer to Diagnostic Function − OBD-II Drive Cycle − 

Pattern 16 

P.13A-9

 

.

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.

AK703260

Start

Yes

Yes

Yes

No

No

No

Frequency > 10Hz

Continuous

failure for 20secs

Malfunction

End

Good

Monitoring
conditions