Mitsubishi Galant (2004+). Manual - part 1279

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-809

STEP 13. Check for harness damage between power 
steering pressure switch connector B-31 (terminal No. 1) 
and PCM connector B-21 (terminal No. 78). 

Q: Is the harness wire in good condition? 

YES : Replace the PCM. Then go to Step 14.
NO :  Repair it. Then go to Step 14.

AK303162

1

AB

POWER STEERING
PRESSURE SWITCH

B-31 (B)

CONNECTOR: B-31

HARNESS
CONNECTOR:
COMPONENT SIDE

AK303018

55

56

54 53 52 51

57

62 61 60 59 58

63

69 68 67 66 65 64

70

75 74 73 72 71

76

82 81 80 79 78 77

83

CONNECTOR: B-21

PCM

AB

HARNESS CONNECTOR: 
COMPONENT SIDE

AIR CLEANER

B-21 (B)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-810

STEP 14. Using scan tool MB991958, check data list item 
27: Power Steering Pressure Switch. 

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting 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 

27, 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?

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

DTC P0554: Power Steering Pressure Switch Circuit Intermittent

AC305412

AB

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AK302866

YELLO

W

POWERTRAIN
CONTROL
MODULE (PCM)

1

B-31

(MU801211)

POWER STEERING
PRESSURE SWITCH

78

1

Power Steering Pressure Switch Circuit

B-21

52

51

53 54 55 56

57

58 59 60 61 62

63

64 65 66 67 68 69

70

71 72 73 74 75

76

77 78 79 80 81 82

83

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-811

.

CIRCUIT OPERATION

• A battery positive voltage is applied to the power 

steering pressure switch output terminal (terminal 
No. 1) from the PCM (terminal No. 78) via the 
resistor in the PCM.

.

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 PCM.

• 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 PCM 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

.

AK303161

AB

POWER STEERING
PRESSURE SWITCH

B-31 (B)

CONNECTOR: B-31

AK303119

CONNECTOR: B-21

PCM

AB

AIR CLEANER

B-21

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI) <3.8L ENGINE>

13B-812

DTC SET CONDITIONS

Logic Flow Chart

.

Check Conditions

• Engine coolant temperature is higher than 30°C 

(86

°F).

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

Judgment Criteria

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

sure switch is 10 Hz or more for 20 seconds.

.

OBD-II DRIVE CYCLE PATTERN
None.

.

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

• Power steering pressure switch failed.

• Incorrect power steering fuid level.

• Incorrect oil pump pressure.

• Harness damage in power steering pressure 

switch circuit, or connector damage.

• PCM failed.

START

END

NO

NO

YES

YES

YES

NO

MALFUNCTION

GOOD

CONTINUOUS FAILURE 

FOR 20secs

FREQUENCY > 10Hz

MONITORING

CONDITIONS

AK302410