Engine Controls - System/component Tests Mitsubishi Galant VII

INTRODUCTION

Note. Testing individual components does not isolate shorts or opens. Perform all voltage tests using a Digital Volt-Ohmmeter (DVOM) with minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use ohmmeter to isolate wiring harness shorts or opens.

Before testing separate components or systems, perform procedures in BASIC TESTING article. Since many computer-controlled and monitored components set a trouble code if they malfunction, also perform procedures in TESTS W/CODES article.

NON-TURBOCHARGED

Note. For diagnosis and testing information concerning Variable Induction Control (VIC) motor position sensor, see TESTS W/CODES article.

CONTROL UNIT

Note. For Engine Control Module (ECM) location, see ENGINE CONTROL MODULE (ECM) LOCATION table. To identify ECM power and ground circuits, see appropriate wiring diagram in WIRING DIAGRAMS article.

Ground Circuits

1. Turn ignition off. Using an ohmmeter, check continuity between chassis ground and ECM ground terminals. See «GROUND TERMINAL IDENTIFICATION»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. Ohmmeter should indicate zero ohms. If reading is not zero ohms, check and repair open circuit between ECM connector and ground.
2. Connect voltmeter negative lead to chassis ground. Connect positive lead to ECM ground terminals. See «GROUND TERMINAL IDENTIFICATION»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. (Scheme 1) With engine running, voltmeter should indicate less than one volt. If voltmeter reading is greater than one volt, check for open, corrosion or loose connection in ground circuit.

Power Circuits

Turn ignition on. Check for battery voltage on ECM power terminals. See POWER TERMINAL IDENTIFICATION table. If battery voltage is not present, check operation of MFI relay. See RELAYS under MOTORS, RELAYS & SOLENOIDS.

Scheme 1

GROUND TERMINAL IDENTIFICATION

POWER TERMINAL IDENTIFICATION

ENGINE CONTROL MODULE (ECM) LOCATION

Barometric Pressure Sensor

Sensor is a part of airflow sensor assembly. See TESTS W/CODES article.

Camshaft Position Sensor

See TESTS W/CODES article.

Closed Throttle Position Switch

See THROTTLE POSITION SENSOR in TESTS W/CODES article.

Coolant Temperature Sensor

See TESTS W/CODES article.

Crankshaft Position Sensor

See TESTS W/CODES article.

EGR Temperature Sensor

See TESTS W/CODES article.

Idle Position Switch

See THROTTLE POSITION SENSOR in TESTS W/CODES article.

Note. For circuit identification, see appropriate wiring diagram in WIRING DIAGRAMS article

Scheme 2

1. Switch is mounted to automatic transmission, near shift lever mechanism. Ensure switch is adjusted properly. Switch output can be affected by improper adjustment. Using DVOM, check continuity between selected terminals. Continuity should exist between ignition switch and ECM when shift selector lever is in Park or Neutral position. See «PARK/NEUTRAL POSITION (PNP) SWITCH TERMINAL IDENTIFICATION»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table.
2. Using DVOM, measure supply voltage from ignition switch in start position. Disconnect ECM harness connector. See «ENGINE CONTROL MODULE (ECM) LOCATION»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table under COMPUTERIZED ENGINE CONTROLS. Disconnect park/neutral position switch connector. Turn ignition switch to START position. Measure voltage between switch (start circuit) and vehicle ground. See «PARK/NEUTRAL POSITION (PNP) SWITCH TERMINAL IDENTIFICATION»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. If battery voltage is present, go to next step. If voltage is less than battery voltage, inspect and repair circuit.
3. Using DVOM, check continuity between PNP switch and ECM. See «PARK/NEUTRAL POSITION (PNP) SWITCH TERMINAL IDENTIFICATION»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. If continuity does not exist in either circuit, inspect and repair faulty circuit as needed. If continuity exists and all preceding tests do not show any system or component malfunction and ECM is suspected, substitute ECM with known good component and retest. PARK/NEUTRAL POSITION (PNP) SWITCH TERMINAL IDENTIFICATION (1) Application PNP Terminal No. To ECM Terminal No. (Start) PNP Terminal No. To ECM Terminal No. (Run) Galant 5 & 71 8 & 51 (1) For PNP harness connector terminal identification, See 2.

Intake Air Temperature Sensor

See TESTS W/CODES article.

Oxygen (O2) Sensor

See TESTS W/CODES article.

Power Steering Oil Pressure Switch

1. Disconnect switch connector at pump. Using DVOM, check continuity between switch and vehicle ground. Continuity should not exist with wheels straight ahead and engine idling. Continuity should be present when wheels are turned to lock position or when pump pressure is increased.
2. Check continuity of circuit between switch and ECM. Disconnect power steering oil pressure switch harness connector and ECM harness connector. See «ENGINE CONTROL MODULE (ECM) LOCATION»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table under COMPUTERIZED ENGINE CONTROLS. Connect jumper wire between ECM terminal and vehicle ground. See «POWER STEERING PRESSURE SWITCH ECM TERMINAL IDENTIFICATION»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. Using DVOM, check for continuity between switch harness connector and vehicle ground. Check and repair circuit if no continuity exists. Go to step 3) if continuity exists.
3. Connect ECM harness connector. Turn ignition on. Using DVOM, measure voltage at switch harness connector. System is okay if battery voltage exists. Substitute ECM with known good unit if voltage does not exist.

POWER STEERING PRESSURE SWITCH ECM TERMINAL IDENTIFICATION

Throttle Position Sensor

See TESTS W/CODES article.

Vehicle Speed Sensor

See TESTS W/CODES article.

IAC Motor

See IDLE CONTROL SYSTEM .

RELAYS

Note. For circuit identification, see appropriate wiring diagram in WIRING DIAGRAMS article

Scheme 3

1. Remove suspected relay from underhood relay block. Connect 12-volt power supply to relay terminals No. 2 and 4. (Scheme 3) Continuity should exist between terminals No. 1 and 3. Replace relay if continuity is not present. If continuity is present, go to next step.
2. With ignition on, check voltage between each relay receptacle terminal No. 4 and vehicle ground. If battery voltage is not present, inspect and repair circuit between ignition switch and relay. If battery voltage is present, go to next step.
3. Using ohmmeter, check continuity between each relay receptacle terminal No. 3 and vehicle ground. If continuity does not exist, inspect and repair ground circuit as needed. If continuity exists, go to next step.
4. Disconnect ECM harness connector. See «ENGINE CONTROL MODULE (ECM) LOCATION»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table under COMPUTERIZED ENGINE CONTROLS. Using ohmmeter check continuity between relay receptacle terminal No. 2 and appropriate ECM terminal. See «FAN CONTROL RELAY ECM CIRCUIT IDENTIFICATION»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table.
5. If continuity does not exist, inspect and repair faulty circuit(s) as needed. If continuity exists and all preceding tests do not show any system or component malfunction and ECM is suspected, substitute ECM with known good component and retest. FAN CONTROL RELAY ECM CIRCUIT IDENTIFICATION Application Lo Fan Circuit No. Hi Fan Circuit No. Galant 16 3 NOTE: For MFI relay location, see «MFI RELAY LOCATION»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. MFI RELAY LOCATION Application Location Galant Behind glove box, next to ECM

Scheme 4

1. This step checks ignition supply voltage to ECM. Disconnect ECM harness connector. Turn ignition on. Using DVOM, measure voltage between ECM harness connector terminal No. 62 and vehicle ground. (Scheme 1) If battery voltage is present, go to step 2). If battery voltage is not present, check and repair circuit between ignition switch and ECM harness connector.
2. This step checks continuity of circuit between MFI relay and ECM. Disconnect ECM harness connector. Using DVOM, check continuity between MFI relay harness connector terminal No. 6 and ECM harness connector terminal No. 108. If continuity exists, go to step 4). If continuity does not exist, check and repair circuits between MFI relay harness connector and ECM.
3. This step checks continuity of circuit between MFI relay and ECM. Check continuity between MFI relay harness connector terminal No. 2 (except Galant) or terminal No. 3 (Galant) and ECM harness connector terminals No. 12 and 25. If continuity exists, go to step 5). If continuity does not exist, check and repair circuits between MFI relay harness connector and ECM.
4. If MFI relay tests okay in following steps, substitute ECM with known good unit and retest. Measure resistance between MFI relay terminals No. 5 and 7. Resistance should be approximately 90 ohms. Check continuity between terminals No. 6 and 8. Continuity should exist in only one direction. Replace MFI relay if continuity is not as specified.
5. Connect 12-volt power source between relay terminals No. 5 and 7. Connect positive lead to terminal No. 7. With relay energized, battery voltage should exist between terminals No. 1 and 5. With power source removed, voltage should not exist.
6. Move 12-volt power source to relay terminals No. 6 and 8. Connect positive lead to terminal No. 8. With relay energized, continuity should exist between terminals No. 2 and 4 and between terminals No. 3and 4. With power source removed, continuity should not exist. Replace MFI relay if measurements are not as specified.

EGR Control Solenoid Valve

See EXHAUST GAS RECIRCULATION (EGR) under EMISSION SYSTEMS & SUB-SYSTEMS.

Purge Control Solenoid Valve

See FUEL EVAPORATION under EMISSION SYSTEMS & SUB-SYSTEMS.

FUEL DELIVERY

Note. For fuel system pressure testing, see BASIC TESTING article.

Fuel Injectors

See TESTS W/CODES article.

IDLE AIR CONTROL (IAC) MOTOR

Note. For diagnosis and testing information concerning IAC motor position sensor, see TESTS W/CODES article.

Note. Procedures are provided by manufacturer for component testing using an engine analyzer with oscilloscope capability. Refer to manufacturer's operation manual for instructions in use of oscilloscope. Go to step 10) for test procedures using oscilloscope.

Scheme 5

Scheme 6

1. Using a stethoscope, listen for operating sound of IAC motor when ignition switch is placed in ON position. If no operating sound can be heard, proceed with following tests.
2. Disconnect IAC harness connector. Install Test Harness (MD998463-01 ) if necessary to aid testing. Using DVOM, measure resistance between IAC terminals No. 1 and 2 and between terminals No. 1 and 3. (Scheme 5) Resistance should be 28-33 ohms.
3. Measure resistance between terminals No. 4 and 5 and between terminals No. 5 and 6. Resistance should be 28-33 ohms. If resistance measurements are not within specification, replace IAC motor. Go to step 4) if IAC motor is within specification.
4. Remove throttle body. See «REMOVE/INSTALL/OVERHAUL»(ref-19023) article. Remove stepper motor from throttle body. Connect Test Harness (MD998463-01 ) to IAC motor.
5. Hold IAC motor in hand. Place thumb on top of plunger. Connect positive lead of 6-volt power source to White and Green clips of test harness. Individually connect, then disconnect, negative lead of power source to Red and Black clips, Blue and Black clips, Blue and Yellow clips, and Red and Yellow clips. Finish by connecting negative lead to Red and Black clips again.
6. Connect negative lead to test leads in reverse sequence of step 5). Stepper motor should vibrate with each connection. Replace IAC motor if vibration is not felt with each connection.
7. Ensure MFI relay is functioning properly. See «RELAYS»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests__relays) under MOTORS, RELAYS & SOLENOIDS. Disconnect IAC motor harness connector. Turn ignition on. Using DVOM, check for battery voltage between terminal No. 2 and vehicle ground and terminal No. 5 and vehicle ground. If voltage is not battery voltage, check and repair circuits between MFI relay and IAC motor. If battery voltage exists, go to step 8).
8. This step checks for continuity between MFI relay and IAC motor. Check for continuity between MFI relay terminals No. 4 and 5 and IAC motor terminals No. 2 and 5. (Scheme 4)and (Scheme 5). If continuity exists, go to step 9). If continuity does not exist, check and repair circuits.
9. This step checks for continuity between ECM and IAC motor. Disconnect ECM harness connector. Check continuity of specified circuits. (Scheme 1)and (Scheme 5). See «IAC TO ECM CIRCUIT CONTINUITY CHECK»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. Check and repair any circuits without continuity. IAC TO ECM CIRCUIT CONTINUITY CHECK IAC Terminal No. ECM Terminal No. 1 4 3 17 4 5 6 18
10. Connect ECM harness connector. Install harness connector and Test Harness (MB998463-01 ). Using engine analyzer with oscilloscope capability, connect special patterns probe to selected leads of test harness. Leads used are Red, Green, Black and Yellow clips.
11. Start engine, and allow it to idle. Connect special patterns probe to one test lead. Turn A/C on. When IAC motor operates to increase engine speed to compensate for A/C system, a waveform should be displayed. Conduct test with each remaining test lead and compare pattern to illustration. (Scheme 6)
12. If waveform is different, replace IAC motor. If all preceding tests do not show any system or component malfunction and ECM is suspected, replace ECM and retest system.

IGNITION SYSTEM

Note. For basic ignition checks, see BASIC TESTING article.

See TESTS W/CODES article.

See TESTS W/CODES article.

Knock Sensor

See TESTS W/CODES article.

See TESTS W/CODES article.

1. Label and disconnect both vacuum hoses from solenoid valve. See «VACUUM DIAGRAMS»(ref-19009) article. Disconnect electrical connector. Connect hand vacuum pump to solenoid valve nipple where Green-striped hose was connected. Apply vacuum to solenoid valve. Vacuum should hold.
2. Apply battery voltage to terminals of solenoid valve. Vacuum should bleed down when voltage is applied to terminals. Using an ohmmeter, check resistance across solenoid valve terminals. Reading should be 36-44 ohms at 68°F (20°C). If reading is not within specification, replace valve.
3. Disconnect EGR solenoid harness connector. Turn ignition on. Using DVOM, measure voltage at harness connector MFI relay power supply terminal. See «EGR CONTROL SOLENOID HARNESS CONNECTOR TERMINAL IDENTIFICATION»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table.
4. If battery voltage is present, go to step 5). If battery voltage is not present, check and repair circuit between purge solenoid and MFI relay. If circuit is okay, inspect MFI relay. See «RELAYS»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests__relays) under MOTORS, RELAYS & SOLENOIDS.
5. Disconnect ECM harness connector. See «ENGINE CONTROL MODULE (ECM) LOCATION»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table under COMPUTERIZED ENGINE CONTROLS. Connect jumper wire between ECM terminal No. 6 and vehicle ground. (Scheme 1)
6. Using DVOM, check for continuity between harness connector ECM control circuit terminal and vehicle ground. See «PURGE CONTROL SOLENOID HARNESS CONNECTOR TERMINAL IDENTIFICATION»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. If continuity does not exist, check and repair circuit as needed. If continuity exists and preceding tests do not show any system or component malfunction and ECM is suspected, substitute ECM with known good unit and retest system. EGR CONTROL SOLENOID HARNESS CONNECTOR TERMINAL Application Terminal No. Wire Color MFI Relay Circuit 1 Black/Red ECM Control Circuit 2 Brown

Purge Control Valve

Remove purge control valve. Valve is mounted between canister and purge control solenoid valve. See VACUUM DIAGRAMS article. Apply vacuum to diaphragm of vacuum valve. Valve should begin opening at approximately 15.7 in. Hg. Observe operation of valve through by-pass opening.

1. Label and disconnect both vacuum hoses from solenoid valve. Disconnect electrical connector. Connect hand vacuum pump to solenoid valve nipple where Red-striped hose was connected. Apply vacuum to solenoid valve. Vacuum should hold.
2. Apply battery voltage to terminals of solenoid valve. Vacuum should bleed down when voltage is applied to terminals. Using an ohmmeter, check resistance across solenoid valve terminals. Reading should be 36-44 ohms at 68°F (20°C). If reading is not within specification, replace valve.
3. Disconnect purge solenoid harness connector. Turn ignition on. Using DVOM, measure voltage at harness connector MFI relay power supply terminal. See «PURGE CONTROL SOLENOID HARNESS CONNECTOR TERMINAL IDENTIFICATION»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table.
4. If battery voltage is present, go to step 5). If battery voltage is not present, check and repair circuit between purge solenoid and MFI relay. If circuit is okay, inspect MFI relay. See «RELAYS»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests__relays) under MOTORS, RELAYS & SOLENOIDS.
5. Disconnect ECM harness connector. See «ENGINE CONTROL MODULE (ECM) LOCATION»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table under COMPUTERIZED ENGINE CONTROLS. Connect jumper wire between ECM terminal No. 9 and vehicle ground. (Scheme 1)
6. Using DVOM, check for continuity between harness connector ECM control circuit terminal and vehicle ground. See «PURGE CONTROL SOLENOID HARNESS CONNECTOR TERMINAL IDENTIFICATION»(/mitsubishi/galant/vii-1992-1997/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. If continuity does not exist, check and repair circuit as needed. If continuity exists and preceding tests do not show any system or component malfunction and ECM is suspected, substitute ECM with known good unit and retest system. PURGE CONTROL SOLENOID HARNESS CONNECTOR TERMINAL Application Terminal No. Wire Color MFI Relay Circuit SOHC 2 Black/Red DOHC 2 Red ECM Control Circuit SOHC 1 Green/Red DOHC 1 Brown/Yellow

PCV Valve

Remove PCV valve. Shake valve by hand. Valve should rattle if moving freely. Apply air pressure to valve. Air should flow in one direction only. Connect PCV valve to vacuum hose and start engine. Ensure vacuum is flowing through valve.

MISCELLANEOUS CONTROLS

Note. Although some of the controlled devices listed here are not technically engine performance components, they can affect driveability if they malfunction.

A/C Switch & Compressor Clutch Relay

Using DVOM, measure power supply voltage of ECM. Disconnect ECM connector. Turn A/C switch and ignition switch to ON positions. Measure voltage between specified ECM terminals and vehicle ground. See A/C POWER ECM TERMINAL LOCATION table. Voltage should be 6 volts or greater. If voltage is not battery voltage, check and repair circuit.

A/C POWER ECM TERMINAL LOCATION

See also:
• WIRING DIAGRAMS
• ENGINE CONTROL MODULE (ECM) LOCATION
• RELAYS