Engine Controls - System & Component Testing Mitsubishi Montero III

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 DIAGNOSTIC PROCEDURES article. Since many computer-controlled and monitored components set a diagnostic trouble code if they malfunction, also perform procedures in appropriate SELF-DIAGNOSTICS article.

CONTROL UNIT

Note. For Engine Control Module (ECM) or Powertrain Control Module (PCM) location, see POWERTRAIN CONTROL MODULE (ECM/PCM) LOCATION table. To identify ECM/PCM power and ground terminals, see appropriate pin voltage chart in PIN VOLTAGE CHARTS article. To identify ECM/PCM power and ground circuits, see appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS.

POWERTRAIN CONTROL MODULE (ECM/PCM) LOCATION

Power Circuits

Turn ignition on. Backprobe and check for battery voltage at ECM/PCM power terminals. If battery voltage is not present, check operation of MFI relay. See FUEL PUMP RELAY & MFI RELAY under RELAYS in MOTORS, RELAYS & SOLENOIDS. If relay is okay, check suspect circuit between ECM/PCM and relay. Perform repairs as necessary.

Ground Circuits

1. Turn ignition off. Backprobe and check for continuity between chassis ground and ECM/PCM ground terminal(s). If continuity exists, go to next step. If continuity does not exist, repair open circuit between ECM/PCM connector and chassis ground. Ensure suspect ground connection is clean and tight.
2. Backprobe and measure voltage between chassis ground and ECM/PCM ground terminal(s). With engine operating at normal operating temperature, voltage should be less than one volt. If voltage is more than one volt, check for open, corrosion or loose connection in ground circuit.

ENGINE SENSORS & SWITCHES

Note. For circuit identification, see appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. For connector views, see TERMINAL IDENTIFICATION in appropriate SELF-DIAGNOSTICS article, unless otherwise noted.

Accelerator Pedal Position (APP) Sensor - Diamante With Traction Control

1. Disconnect accelerator pedal position sensor connector. Check resistance between accelerator pedal position sensor connector (component side) terminals No. 1 and 4. Resistance should be 3500-6500 ohms. If sensor resistance is not as specified, replace accelerator pedal position sensor. If sensor resistance is as specified, go to next step.
2. While slowly opening throttle valve, check resistance between accelerator pedal position sensor connector terminals No. 1 and 2. Resistance should change smoothly in proportion to opening angle of throttle valve. If sensor resistance is not as specified, replace accelerator pedal position sensor. For accelerator pedal position sensor adjustment procedures, see «ACCELERATOR PEDAL POSITION SENSOR ADJUSTMENT»(ref-135481-S08170623912002022200000) under THROTTLE POSITION & ACCELERATOR PEDAL POSITION SENSORS in ON-VEHICLE ADJUSTMENTS article.

Barometric Pressure (BARO) Sensor

For all vehicles except Mirage 1.5L, BARO sensor is part of the Volume Air Flow (VAF) sensor assembly. Mirage 1.5L uses input from the Manifold Absolute Pressure (MAP) sensor under conditions of key on, engine off, to determine barometric pressure. To check BARO sensor and circuit, proceed to the apropriate SELF-DIAGNOSTICS article and reference the DTC.

Camshaft Position (CMP) Sensor

On Diamante, Eclipse 3.0L, Galant 3.0L and Mirage 1.5L, CMP sensor is located in distributor assembly. On these vehicles, test at distributor assembly 7-pin connector. On all other vehicles, test at CMP sensor 3-pin connector. Using test harness, or backprobing, connect lab scope pick-up to distributor assembly connector terminal No. 5, or CMP sensor connector terminal No. 2. Start engine. Compare waveform to normal waveform. (Scheme 56)- (Scheme 60). Waveform frequency should increase as engine speed is increased.

Note. Lancer: When measuring with the ECM or PCM side connector, connect an oscilloscope probe to terminal 88 (M/T) or terminal 56 (A/T).

Crankshaft Position (CKP) Sensor

Using test harness, or backprobing, connect lab scope pick-up to CKP sensor connector terminal No. 3 for Lancer, and No. 2 for all other models. Start engine. Compare waveform to normal waveform. (Scheme 56)- (Scheme 60). Waveform frequency should increase as engine speed is increased.

Scheme 56

Scheme 57

Scheme 58

Scheme 59

Scheme 60

Engine Coolant Temperature (ECT) Sensor

Disconnect ECT sensor connector. Immerse ECT sensor in hot water. Check resistance between ECT sensor terminals. See ECT SENSOR RESISTANCES table.

ECT SENSOR RESISTANCES

Heated Oxygen Sensor (HO2S)

1. Disconnect suspect HO2S connector and connect test harness set to sensor. Using a test harness set, measure HO2S heater resistance between sensor terminals. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. If resistance is as specified, go to next step. See «HO2S HEATER RESISTANCE»(/mitsubishi/montero/iii-1999-2006/remont/testing-diagnostics/#engine-controls-system-component-testing) table. If HO2S heater resistance is not as specified, replace HO2S and recheck system for proper operation. HO2S HEATER RESISTANCE HO2S Location (1) Ohms Except Diamante & Mirage 1.5L Front 4.5-8.0 Rear 11.0-18.0 Diamante Front 4.5-8.0 Rear 7.0-40.0 Mirage 1.5L Front & Rear 4.5-8.0 (1) Measured at 68°F (20°C). CAUTION: HO2S will be damaged if jumper wires are incorrectly connected to sensor.
2. Start engine and allow to idle until engine coolant temperature is 176°F (80°C) or more. Using fused jumper wires, carefully energize HO2S heater. Snap accelerate engine several times while measuring sensor output voltage. As air-fuel mixture becomes more rich, HO2S output voltage should be 600-1000 millivolts. Replace HO2S if output voltage is not as specified. Recheck system for proper operation.

Intake Air Temperature (IAT) Sensor

Note. On all models except Mirage 1.5L, IAT sensor is a part of Volume Air Flow (VAF) sensor assembly. On Mirage 1.5L, IAT is a separate unit.

1. On Mirage 1.5L, disconnect IAT sensor connector and check resistance across IAT sensor terminals. On all other models, disconnect VAF sensor connector. Check resistance between VAF sensor connector terminals No. 5 and 6. Compare air temperature and IAT sensor resistance value with standard values. See «IAT SENSOR RESISTANCES»(/mitsubishi/montero/iii-1999-2006/remont/testing-diagnostics/#engine-controls-system-component-testing) table.
2. Using hair dryer, heat IAT sensor and check resistance. Resistance should decrease as IAT temperature increases.

IAT SENSOR RESISTANCES

Knock Sensor

See DTC P0325: KNOCK SENSOR (KS) CIRCUIT MALFUNCTION in appropriate SELF-DIAGNOSTICS article.

Manifold Differential Pressure (MDP) Sensor

All models, except Mirage 1.5L, have MDP sensor. See DTC P1400: MANIFOLD DIFFERENTIAL PRESSURE (MDP) SENSOR CIRCUIT MALFUNCTION test in appropriate SELF-DIAGNOSTICS article.

Throttle Position (TP) Sensor

1. Disconnect TP sensor connector. Check resistance between TP sensor connector (component side) terminals No. 2 and 3 for Lancer and No. 1 and 4 for all other models. Resistance should be 2000-4000 ohms (Lancer) or 3500-6500 ohms (all other models). If resistance is not as specified, replace TP sensor. If resistance is as specified, go to next step.
2. While slowly opening throttle valve, check resistance between TP sensor connector terminals No. 3 and 4 (Diamante), No. 2 and 4 (Mirage), No. 1 and 2 (Lancer) or No. 1 and 3 (all other models). Resistance should change smoothly in proportion to opening angle of throttle valve. If resistance is not as specified, replace TP sensor. For TP sensor adjustment procedures, see appropriate TP SENSOR ADJUSTMENT under «THROTTLE POSITION (TP) SENSOR & ACCELERATOR PEDAL POSITION SENSORS»(ref-135481-S11413358142002022200000) in ON-VEHICLE ADJUSTMENTS article.

Vehicle Speed Sensor (VSS)

Except Lancer - Remove VSS from rear of transmission or top of transaxle. Connect 3-10 k/ohm resistor (Scheme 61) Connect voltmeter between terminals No. 2 and 3. Spin shaft of VSS and check for voltage pulsations. There should be about 4 voltage pulsations per revolution. If there are not 4 pulsations per revolution, replace VSS.

Lancer

1. Do not disconnect the ECM connector C-115.
2. Disconnect the combination meter connector, auto-cruise control-ECU connector and A/C-ECU connector.
3. Connect the oscilloscope probe to ECM terminal 86 by backprobing. (Scheme 62)
4. Start the engine.
5. Check that the waveform pattern shown is similar to the illustration (while the vehicle is being moved). (Scheme 62)
6. Turn the ignition switch to the "LOCK" (OFF) position.

Scheme 61

Scheme 62

Volume Air Flow (VAF) Sensor

1. Using test harness, or backprobing, connect lab scope pick-up to VAF sensor connector terminal No. 3. With key on, engine off, output frequency of VAF sensor should be zero. If other than zero, malfunction is in VAF sensor or ECM/PCM.
2. Start engine. Compare waveform to normal waveform. (Scheme 63) Waveform should be stable with frequency increasing as engine speed increases. A VAF with internal damage will show an unstable pattern with non-uniform frequency. An ignition leak during acceleration may temporarily distort the waveform pattern on a good VAF sensor.
3. Using scan tool, or lab scope, compare VAF sensor output frequency with standard values. See «NORMAL VAF SENSOR FREQUENCY VALUES»(/mitsubishi/montero/iii-1999-2006/remont/testing-diagnostics/#engine-controls-system-component-testing) table. If idling is possible even though VAF sensor frequency is outside normal values, fault is probably outside of VAF sensor. Check for intake air restrictions or disturbances. Check for intake manifold leaks, ignition problems and compression.

NORMAL VAF SENSOR FREQUENCY VALUES

Scheme 63

Closed Throttle Position Switch

Disconnect Throttle Position (TP) sensor connector. Check continuity between indicated TP sensor connector terminals with accelerator pedal depressed and released. See CLOSED THROTTLE POSITION SWITCH CHECK table. When accelerator pedal is depressed, continuity should not exist. When accelerator pedal is released, continuity should exist.

CLOSED THROTTLE POSITION SWITCH CHECK (1)

Park Neutral Position (PNP) Switch (Except Montero & Montero Sport)

Check for continuity between indicated PNP switch terminals. See PNP SWITCH CONTINUITY CHECK (EXCEPT MONTERO & MONTERO SPORT) table. (Scheme 64)

PNP SWITCH CONTINUITY CHECK (EXCEPT MONTERO & MONTERO SPORT)

Scheme 64

Park Neutral Position (PNP) Switch (Montero)

Check for continuity between indicated PNP switch terminals. See PNP SWITCH CONTINUITY CHECK (MONTERO) table. (Scheme 65)

PNP SWITCH CONTINUITY CHECK (MONTERO) (1)

Scheme 65

Park Neutral Position (PNP) Switch (Montero Sport)

Check for continuity between indicated PNP switch terminals. See PNP SWITCH CONTINUITY CHECK (MONTERO SPORT) table. (Scheme 66)

PNP SWITCH CONTINUITY CHECK (MONTERO SPORT)

Scheme 66

Power Steering Oil Pressure (PSP) Switch

1. Disconnect pressure hose from oil pump. (Scheme 67) Install adapter on oil pump. Install adapter on disconnected hose. Connect pressure gauge and shutoff valve between adapters. Open shutoff valve. Bleed steering hydraulic system. See HYDRAULIC SYSTEM BLEEDING in appropriate POWER STEERING article in STEERING.
2. Install a thermometer in fluid reservoir. Start engine and allow it to idle. Turn steering wheel several times until fluid temperature reaches 122-140°F (50-60°C). Disconnect PSP switch connector. Install a DVOM between ground and PSP switch terminal. (Scheme 67) Note continuity reading on DVOM. Go to next step.
3. With engine idling, gradually close shutoff valve to increase power steering system pressure. Check pressure when PSP switch is actuated by watching for a change in continuity. See «POWER STEERING SWITCH TEST PRESSURES»(/mitsubishi/montero/iii-1999-2006/remont/testing-diagnostics/#engine-controls-system-component-testing) table. Gradually open shutoff valve to decrease pressure. Check pressure when PSP switch is de-actuated. Turn engine off. Replace switch if not to specification.

POWER STEERING SWITCH TEST PRESSURES

Scheme 67

MOTORS, RELAYS & SOLENOIDS

Note. For circuit identification, see appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. For connector views, see TERMINAL IDENTIFICATION in appropriate SELF-DIAGNOSTICS article, unless otherwise noted.

Idle Air Control Motor

See IDLE AIR CONTROL (IAC) MOTOR under IDLE CONTROL SYSTEM.

Fuel Pump Relay & MFI Relay

Remove MFI or fuel pump relay. Check resistance between relay terminals No. 2 and 4 (Lancer - terminals No. 2 and 3). Resistance should be about 70 ohms. Connect jumper wire between battery positive terminal and relay terminal No. 4 (Lancer - terminal No. 3). Connect second jumper wire between battery negative terminal and MFI/fuel pump relay terminal No. 2. With relay energized, continuity should exist between terminals No. 1 and 3 (Lancer - terminals No. 1 and 4). With power source removed, continuity should not exist between terminals No. 1 and 3 (Lancer - terminals No. 1 and 4). If relay does not test as specified, replace MFI/fuel pump relay.

Radiator Cooling Fan Control Relay (Diamante & Mirage)

Remove radiator cooling fan relay. Check continuity between radiator cooling fan relay terminals No. 1 and 3. (Scheme 68) Continuity should exist. Connect jumper wire between battery positive terminal and radiator cooling fan relay terminal No. 1. Connect second jumper wire between battery negative terminal and radiator cooling fan relay terminal No. 3. With relay energized, continuity should exist between terminals No. 4 and 5. With power source removed, continuity should not exist between terminals No. 4 and 5. If relay does not test as specified, replace radiator cooling fan relay.

Scheme 68

Radiator Cooling Fan Control Relay (Eclipse & Galant)

Remove radiator cooling fan relay. Check continuity between radiator cooling fan relay terminals No. 1 and 3. (Scheme 69) Continuity should exist. Connect jumper wire between battery positive terminal and radiator cooling fan relay terminal No. 3. Connect second jumper wire between battery negative terminal and radiator cooling fan relay terminal No. 1. With relay energized, continuity should exist between terminals No. 2 and 5. With power source removed, continuity should not exist between terminals No. 2 and 5. If relay does not test as specified, replace radiator cooling fan relay.

Scheme 69

Radiator Cooling Fan Control Relay (Lancer)

Remove radiator cooling fan relay. Check continuity between radiator cooling fan relay terminals No. 2 and 4. (Scheme 70) Continuity should exist. Connect jumper wire between battery positive terminal and radiator cooling fan relay terminal No. 1. Connect second jumper wire between battery negative terminal and radiator cooling fan relay terminal No. 3. With relay energized, continuity should exist between terminals No. 2 and 4. With power source removed, continuity should not exist between terminals No. 2 and 4. If relay does not test as specified, replace radiator cooling fan relay.

Scheme 70

EGR Solenoid

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

Purge Solenoid

See appropriate PURGE SOLENOID under FUEL EVAPORATION under EMISSION SYSTEMS & SUB-SYSTEMS.

Ventilation Solenoid

See VENTILATION SOLENOID under FUEL EVAPORATION under EMISSION SYSTEMS & SUB-SYSTEMS.

FUEL SYSTEM

Note. For circuit identification, see appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. For connector views, see TERMINAL IDENTIFICATION in appropriate SELF-DIAGNOSTICS article, unless otherwise noted.

FUEL DELIVERY

Note. For fuel system pressure testing, see BASIC DIAGNOSTIC PROCEDURES article.

Fuel Injectors

1. Listen to injectors during cranking and at idle. They should make ticking sound. Frequency of sound should increase as engine speed increases.
2. Disconnect injector 2-pin connector at injector. Check resistance between injector terminals. Injector resistance should be 13-16 ohms at 68°F (20°C). On engines with inaccessible injector connectors, check resistance at the injector intermediate connector. To test right bank injectors on Eclipse 3.0L and Galant 3.0L, disconnect right bank injector intermediate 4-pin connector. To test all injectors on Montero and Montero Sport, disconnect injector intermediate 8-pin connector. To test all injectors on Diamante, disconnect injector intermediate 12-pin connector. Check resistances between indicated terminals. See «INJECTOR CHECK AT INJECTOR INTERMEDIATE CONNECTOR»(/mitsubishi/montero/iii-1999-2006/remont/testing-diagnostics/#engine-controls-system-component-testing) table.
3. If using lab scope, connect lab scope pick-up to ECM/PCM side (ground side) of injector circuit. Start engine. Compare waveform to normal waveform. (Scheme 71)
4. To test injector circuit, see DTC P0201-P0204: INJECTORS NO. 1-4 CIRCUIT MALFUNCTION or DTC P0201-P0206: INJECTORS NO. 1-6 CIRCUIT MALFUNCTION in appropriate SELF-DIAGNOSTICS article.

INJECTOR CHECK AT INJECTOR INTERMEDIATE CONNECTOR

Scheme 71

IDLE CONTROL SYSTEM

Note. For circuit identification, see appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. For connector views, see TERMINAL IDENTIFICATION in appropriate SELF-DIAGNOSTICS article, unless otherwise noted.

IDLE AIR CONTROL (IAC) MOTOR

1. Disconnect IAC motor connector. Check resistance between IAC motor connector terminal No. 2 and either terminal No. 1 or 3. Also check resistance between IAC motor connector terminal No. 5 and either terminal No. 4 or 6. Each resistance should be 28-33 ohms at 68°F (20°C). If resistances are not as specified, replace IAC body assembly. If resistances are as specified, go to next step.
2. If using lab scope, go to step 4. Engine coolant temperature must be 68°F (20°C) or less. If not, an Engine Coolant Temperature (ECT) sensor that is appropriate temperature can plugged into ECT sensor connector. Turn ignition on (engine off) and listen for IAC motor operation sound. Operational sound should be heard when ignition is turned on and off.
3. For testing IAC control circuit, see DTC P0505: IDLE CONTROL SYSTEM MALFUNCTION in appropriate SELF-DIAGNOSTICS article.
4. Using test harness, or backprobing, connect lab scope pick-up, in turn, to IAC motor connector terminals No. 1, 3, 4, and 6. With engine running, compare IAC motor waveform to normal waveform. (Scheme 72)

Scheme 72

IGNITION SYSTEM

Note. For basic ignition checks, see BASIC DIAGNOSTIC PROCEDURES article.

TIMING CONTROL SYSTEMS

For camshaft position sensor, crankshaft position sensor and knock sensor testing, see appropriate test under SENSORS under ENGINE SENSORS & SWITCHES.

EGR System Check

1. Engine coolant temperature should be 68°F (20°C) or less. On Diamante, remove engine cover. Disconnect vacuum hose from EGR valve diaphragm. Connect hand vacuum pump to "T" fitting. Start engine. Check vacuum when engine is cold and engine is revved by quickly opening throttle. There should be no change in vacuum reading.
2. Warm engine coolant to 176°F (80°C) or more. Check vacuum when engine is warm and engine is revved by quickly opening throttle. Vacuum should momentarily increase to more than 3.9 in. Hg (13 kPa). If vacuum momentarily increases, go to next step. If vacuum does not increase over 3.9 in. Hg (13 kPa), perform «VACUUM CONTROL VALVE CHECK»(/mitsubishi/montero/iii-1999-2006/remont/testing-diagnostics/#engine-controls-system-component-testing__vacuum-control-valve-check) and appropriate EGR PORT VACUUM CHECK. Then go to next step.
3. Stop engine. Remove hand vacuum pump and "T" fitting. Connect hand vacuum pump directly to EGR valve. Start and idle engine until warm. On all vehicles except Montero and Lancer, apply 8.7 in. Hg (29 kPa) or more vacuum. On Montero, apply 9.1 in. Hg (31 kPa) or more vacuum. On Lancer, apply 7.9 in. Hg (27 kPa). Engine should idle rough or stall when vacuum is applied to EGR valve. If engine does not idle rough or stall, check EGR valve operation. See «EGR VALVE CHECK»(/mitsubishi/montero/iii-1999-2006/remont/testing-diagnostics/#engine-controls-system-component-testing__egr-valve-check) . Also check EGR valve and EGR passages for restriction.

Vacuum Control Valve Check

1. Disconnect White-striped vacuum hose from vacuum control valve and plug hose end. Connect hand vacuum pump to vacuum control valve port from which hose was removed.
2. Start and idle engine. Check vacuum. With engine idling, vacuum should be between 6.3-7.1 in. Hg (21.3-24.0 kPa).

Scheme 73

EGR Valve Check

Remove EGR valve and check for sticking, carbon deposits or other debris. Clean with suitable solvent as necessary and ensure valve seats properly. Using a vacuum pump, apply 20 in. Hg (67 kPa) vacuum to EGR valve. Vacuum should hold. Apply 1.6 in. Hg (5 kPa) vacuum or less and blow into one EGR port. Air should not blow out of other port. Apply 8.7 in. Hg (29 kPa) vacuum or more and blow into one EGR port. Air should blow out of other port. If EGR valve does not test as specified, replace EGR valve.

EGR Port Vacuum Check (Eclipse Galant, Lancer, Montero & Montero Sport)

1. Disconnect Green-striped vacuum hose from throttle body EGR vacuum port. Connect hand vacuum pump to throttle body EGR vacuum port.
2. Start and idle engine. Check vacuum. Vacuum should be 15 in. Hg (51 kPa) or more.
3. Reset vacuum gauge to zero (release vacuum). Using stop watch, check length of time it takes for vacuum gauge to reach 15 in. Hg (51 kPa). Vacuum should reach specification by one second. If it takes more than one second for vacuum to reach specification, check EGR vacuum port for restriction.

EGR Port Vacuum Check (Diamante & Mirage)

1. Disconnect Green-striped vacuum hose from throttle body EGR vacuum port. Connect hand vacuum pump to throttle body EGR vacuum port.
2. Start engine. Check vacuum while rapidly increasing engine speed. Vacuum should remain fairly constant.

1. Disconnect EGR solenoid electrical connector. Check resistance between EGR solenoid terminals. See «EGR SOLENOID RESISTANCE»(/mitsubishi/montero/iii-1999-2006/remont/testing-diagnostics/#engine-controls-system-component-testing) table. If resistance is not as specified, replace EGR solenoid. If resistance is as specified, go to next step.
2. Label and disconnect vacuum hoses from EGR solenoid. Connect hand vacuum pump to EGR solenoid port "A". (Scheme 74) Apply vacuum. Vacuum should leak. Using battery voltage and ground, energize EGR solenoid. Apply vacuum. Vacuum should hold.

EGR SOLENOID RESISTANCE

Scheme 74

Purge Control System Check (Purge Flow Check)

1. Make sure engine is at normal operating temperature. Disconnect purge hose from EVAP canister. Connect Purge Flow Indicator (MB995061) between canister and purge hose.
2. Place automatic transmission in Park, or manual transmission in Neutral. Ensure lights, cooling fan and accessories are off. Run engine at idle for more than 4 minutes. While suddenly racing engine several times, check purge flow volume. Purge flow volume should be 2.5 SCFH (20 cm 3 /sec) or more. If purge flow is less than specified, retest with vacuum hose disconnected from canister. If purge flow is now as specified, replace canister. If purge flow is still less than specified, check purge solenoid, vacuum port and vacuum hose for clogging.

Purge Port Vacuum Check (Diamante)

1. Disconnect vacuum hose from throttle body purge vacuum port. Connect hand vacuum pump to throttle body purge vacuum port.
2. Start engine. Check vacuum while increasing engine speed. Purge vacuum should increase proportionally with increase in engine speed. If vacuum does not increase with increase in engine speed, check purge port for clogging.

Purge Port Vacuum Check (Mirage)

1. Disconnect vacuum hose from throttle body (1.5L), or intake air plenum (1.8L) purge vacuum port. Connect hand vacuum pump to purge vacuum port.
2. Start engine. Increase engine speed by racing engine. Check vacuum while increasing engine speed. Purge vacuum should remain constant regardless of increase in engine speed. If there is no vacuum, check purge port for clogging.

Purge Solenoid (Except Lancer)

1. On Eclipse 2.4L or Galant 2.4L, remove air intake hose. On all models, disconnect purge solenoid connector. Check resistance between purge solenoid terminals. Resistance should be 30-34 ohms (Except Diamante and Mirage) or 36-44 ohms (Diamante and Mirage) at 68°F (20°C). Replace as necessary. If resistance is as specified, go to next step.
2. Mark and disconnect vacuum hoses from purge solenoid. Connect hand vacuum pump to purge solenoid port furthest from terminal end of solenoid. Connect jumper wires between purge solenoid terminals and battery positive terminal and battery negative terminal.
3. Apply vacuum with battery voltage applied. Vacuum should leak. Disconnect battery voltage and apply vacuum. Vacuum should hold.

Purge Solenoid (Lancer)

1. Disconnect the vacuum hose (black, black with red paint mark) from the EVAP purge solenoid. NOTE: When disconnecting the vacuum hose, always place an identification mark so that it can be reconnected at its original position.
2. Disconnect the harness connector.
3. Connect a hand vacuum pump to nipple (A) of the EVAP purge solenoid.
4. Check airtightness by applying a vacuum with voltage applied directly from the battery to the EVAP purge solenoid valve and without applying voltage. When voltage is applied, the vacuum should leak.
5. Measure the resistance between the terminals of the EVAP purge solenoid. Standard value is 30-34 ohms at 68°F (20°C).
6. Replace solenoid if resistance is out of specification.

1. Locate ventilation solenoid. On Montero, ventilation solenoid is located in engine compartment. On all other vehicles, ventilation solenoid is located near fuel tank. (Scheme 75)- (Scheme 80).
2. Disconnect ventilation solenoid electrical connector. Check resistance across ventilation solenoid terminals. Resistance should be 17-21 ohms at 68°F (20°C). If resistance is not as specified, replace ventilation solenoid. If resistance is as specified, go to next step.
3. Mark and disconnect vacuum hoses from ventilation solenoid. Connect hand vacuum pump to ventilation solenoid port closest to terminal end of solenoid. Connect jumper wires between ventilation solenoid terminals and battery positive terminal and battery negative terminal.
4. Apply vacuum with battery voltage applied. Vacuum should hold. Disconnect battery voltage and apply vacuum. Vacuum should leak.

Scheme 75

Scheme 76

Scheme 77

Scheme 78

Scheme 79

Scheme 80

Vent Valve (Mirage)

1. Locate vent valve. (Scheme 78) Remove vent valve. Blow through ventilation solenoid side port of vent valve. Air should come out from the other side port.
2. Connect hand vacuum pump to ventilation solenoid side vent valve port. When vacuum is applied, air should be drawn only through air filter side port.

Air Filter

Remove EVAP system air filter. (Scheme 76)- (Scheme 80). Check for clogging by blowing through either port.

PCV Valve

1. Remove PCV valve and gently shake valve. Valve should rattle if moving freely.
2. Hold PCV valve with vacuum side down. Insert thin rod in top. Using light pressure, depress end of PCV valve spring .2-.3" (5-10 mm). Release pressure on rod. PCV valve spring should quickly lift rod to its original position.
3. Connect PCV valve to vacuum hose, and start engine. Ensure vacuum is flowing through valve. Clean or replace PCV valve as necessary.

MISCELLANEOUS CONTROLS

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

A/C SYSTEM

Note. To identify ECM/PCM A/C power supply voltage terminals, see appropriate pin voltage chart in PIN VOLTAGE CHARTS article. To identify ECM/PCM A/C power supply circuit, see appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS.

A/C Switch & Compressor Clutch Relay

Using DVOM, check A/C power supply voltage from ECM/PCM. Turn ignition switch to OFF position. Disconnect ECM/PCM connector. Turn A/C switch and ignition switch to ON position. Measure voltage between ECM/PCM A/C power supply terminal and chassis ground. If battery voltage is not present, check and repair circuit(s).

COOLING FAN SYSTEM

For electric cooling fan testing, see appropriate COOLING SYSTEM SPECIFICATIONS & ELECTRIC COOLING FANS article in ENGINE COOLING.

TRANSMISSION

For transmission diagnostic information, see appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.

See also:
• PIN VOLTAGE CHARTS
• POWERTRAIN CONTROL MODULE (ECM/PCM) LOCATION
• FUEL PUMP RELAY & MFI RELAY
• IDLE AIR CONTROL (IAC) MOTOR
• VACUUM CONTROL VALVE CHECK
• EGR VALVE CHECK