Engine Controls - Tests W/codes: Other Mitsubishi Galant VII

Hard Failures

Hard failures cause MIL to glow and remain on until malfunction is repaired. If MIL comes on and remains on (MIL may flash) during vehicle operation, cause of malfunction may be determined by using trouble codes. See TROUBLE CODES . If a sensor fails, ECM will use a substitute value in its calculations to continue engine operation. In this condition, (limp-in mode) vehicle is functional, but loss of good driveability may result.

Intermittent Failures

Intermittent failures may cause MIL to flicker or glow and go out after intermittent trouble code goes away. However, corresponding trouble code will be retained in ECM memory. If related trouble code does not reoccur within a certain time frame, related trouble code will be erased from ECM memory. Intermittent failures may be caused by a sensor, connector or wiring problems. See INTERMITTENTS in TESTS W/O CODES article in the ENGINE PERFORMANCE Section.

SERVICE PRECAUTIONS

Before proceeding with diagnosis, following precautions must be observed

1. Ensure vehicle has a fully charged battery and functional charging system.
2. Visually inspect connectors and circuit wiring being worked on.
3. DO NOT disconnect battery or ECM. This will erase any trouble codes stored in ECM.
4. DO NOT cause short circuits when performing electrical tests. This will set additional trouble codes, making diagnosis of original problem more difficult.
5. DO NOT use a test light in place of a voltmeter.
6. When checking for spark, ensure coil wire is NOT more than 1/4" from chassis ground. If coil wire is more than 1/4" from chassis ground, damage to vehicle electronics and/or ECM may result.
7. DO NOT prolong testing of fuel injectors. Engine may hydrostatically (liquid) lock.
8. When a vehicle has multiple trouble codes, always repair lowest number trouble code first.

RETRIEVING CODES

Manufacturers recommend using a scan tester to retrieve codes. If scan tester is not available, trouble codes may be retrieved using a voltmeter or Malfunction Indicator Light (MIL). See RETRIEVING CODES table for code retrieval method available by model and proceed to appropriate method.

RETRIEVING CODES

Using Scan Tester

1. Refer to manufacturer's operation manual for instructions in use of scan tester. Before entering on-board diagnostics, see «SERVICE PRECAUTIONS»(ref-18964-S26665374722001010800000) . Turn ignition switch to OFF position. Locate Data Link Connector (DLC), next to fuse block. Connect power source terminal of scan tester to cigarette lighter socket.
2. Connect scan tester to DLC. Turn ignition switch to ON position. Read and record scan tester self-diagnostic output. Perform necessary repair(s). See «TROUBLE CODES»(ref-18964-S19811269342001010800000) .

Using Voltmeter

1. Before entering on-board diagnostics, see «SERVICE PRECAUTIONS»(ref-18964-S26665374722001010800000). Turn ignition switch to OFF position. Locate Data Link Connector (DLC), next to fuse block. Connect volt-meter positive lead to DLC self-diagnostic test mode terminal and negative lead to either DLC ground terminal. (Scheme 25)
2. Turn ignition switch to ON position. Disclosure of ECM memory will begin. If 2 or more systems are non-functional, they are indicated by order of increasing code number. Indication is made by 12-volt pulses of voltmeter pointer. A constant repetition of short 12-volt pulses indicates system is normal. If system is abnormal, voltmeter will pulse between zero and 12 volts.
3. Signals will appear on voltmeter as long and short 12-volt pulses. Long pulses represent tens; short pulses represent ones. For example, 4 long pulses and 3 short pulses indicate Code 43. After recording trouble code(s), perform necessary repair(s) to indicated circuit(s). See «TROUBLE CODES»(ref-18964-S19811269342001010800000).

Scheme 25

1. Before entering on-board diagnostics, see «SERVICE PRECAUTIONS»(ref-18964-S26665374722001010800000). Turn ignition switch to OFF position. Locate Data Link Connector (DLC), next to fuse block. Connect Diagnostic Harness (MB99159 ) between DLC self-diagnostic output terminal and chassis ground. (Scheme 25)
2. Turn ignition switch to ON position. Disclosure of ECM memory will begin. If 2 or more systems are non-functional, they are indicated by order of increasing code number. Indication is made by MIL flashes. A constant repetition of short flashes indicates system is normal.
3. If system is abnormal, signals will appear on MIL as long and short flashes. Long flashes represent tens; short flashes represent ones. For example, 4 long flashes and 3 short flashes indicate Code 43. After recording trouble code(s), perform necessary repair(s) to indicated circuit(s). See «TROUBLE CODES»(ref-18964-S19811269342001010800000).

CLEARING CODES

To clear codes using a scan tester, refer to owners manual supplied with scan tester. If scan tester is not available, codes may also be cleared by disconnecting negative battery cable for at least 15 seconds, allowing ECM to clear trouble codes. Reconnect negative battery cable and check for codes to confirm repair.

CODE 11: HEATED OXYGEN SENSOR (HO2S) (4-WIRE OXYGEN SENSOR)

Note. For component terminal identification, see TERMINAL IDENTIFICATION . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

Note. In the following steps, the first terminal listed is positive. The second terminal listed is negative.

1. If using scan tester, go to step 3). Disconnect HO2S connector. Install Test Harness (MB998464 ) between HO2S and HO2S connector. Use DVOM to check resistance between HO2S connector heater terminals No. 2 & 4. HO2S resistance should be 20 ohms at 68°F (20°C). If resistance is not as specified, replace HO2S. If resistance is as specified, go to next step.
2. Using jumper wires, apply 12 volts to HO2S connector heater terminals No 2 & 4. Using DVOM, check voltage between HO2S connector output terminals No. 1 & 3, while repeatedly racing engine. If voltage is not .6-1.0 volt, replace HO2S. If voltage is .6-1.0 volt, go to step 5).
3. Start and warm engine to operating temperature. Using scan tester, read HO2S voltage. While monitoring scan tester, accelerate to 4000 RPM. Suddenly decelerate. Scan tester should read .3 volt or less. Suddenly accelerate. Scan tester should read .5-1.0 volt. If voltage is not as specified, replace HO2S. If voltage is as specified, go to next step.
4. While monitoring scan tester, accelerate to 2000 RPM and decelerate to 700 RPM (idle). Scan tester should switch between .6-1.0 volt and .4 volt or less. If voltage is not as specified, replace HO2S. If voltage is as specified, go to next step.
5. Disconnect HO2S connector. Go to next step.
6. Turn ignition switch to ON position. Using DVOM, check voltage between HO2S connector terminal No. 2 and chassis ground. If system voltage does not exist, repair wiring harness as necessary. If system voltage exists, go to next step.
7. Disconnect HO2S connector. Using DVOM, check for continuity between HO2S connector terminal No. 1 and chassis ground. If continuity does not exist, repair wiring harness as necessary. If no system or component malfunctions occur in preceding tests, go to next step.
8. Disconnect ECM connector. Turn ignition switch to ON position. Using DVOM, check voltage between ECM connector terminal No. 35 and chassis ground. If system voltage does not exist, repair wiring harness as necessary. If system voltage exists and no system or component malfunctions occur in preceding tests, condition required to set trouble code is not present at this time. Test is complete. Intermittent problem may exist. See «TESTS W/O CODES»(ref-19010) article in the ENGINE PERFORMANCE Section.

CODE 12: AIRFLOW SENSOR

Note. For component terminal identification, see TERMINAL IDENTIFICATION . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

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. If using a scan tester, go to step 3).

Scheme 26

1. If using scan tester, go to step 3). Disconnect Airflow Sensor (AFS) connector. Install Test Harness (MB991348 ) between AFS and AFS connector. Using engine analyzer with oscilloscope capability, connect special patterns probe to AFS connector terminal No. 3.
2. Start engine. Verify that wave form high frequency and low frequency patterns are of approximately the same length (time). (Scheme 26) Verify that wave length decreases and frequency increases as engine RPM increases. If conditions are not as specified, replace AFS. If conditions are as specified, go to step 4).
3. Warm vehicle to normal operating temperature. Ensure headlights and accessories are off. Ensure steering wheel is in straight-ahead position. Using scan tester, read Airflow Sensor (AFS) volume (frequency) value. See «AIRFLOW SENSOR VALUES»(ref-18964-S07810573852001010800000) table. Frequency should increase when engine is raced. If values are not as specified, replace AFS. If values are as specified, go to next step. AIRFLOW SENSOR VALUES Application Hz @ 700 RPM Hz @ 2000 RPM 2.4L 18-44 64-104
4. Disconnect AFS connector. Turn ignition switch to ON position. Using DVOM, check voltage between terminal No. 4 and chassis ground. If system voltage does not exist, repair wiring harness as necessary. If system voltage exists, go to next step.
5. With ignition switch in ON position, use DVOM to check voltage between terminal No. 3 and chassis ground. If voltage is not 4.8-5.2 volts, repair wiring harness as necessary. If voltage is as specified, go to next step.
6. Using DVOM, check for continuity between AFS connector terminal No. 5 and chassis ground. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
7. Disconnect AFS connector and ECM connector. Using DVOM, check for continuity between AFS connector terminal No. 7 and ECM connector terminal No. 19. If continuity does not exist on specified circuit(s), repair appropriate circuit for open or short to ground as necessary. If continuity exists, condition required to set trouble code is not present at this time. Test is complete. Intermittent problem may exist. See «TESTS W/O CODES»(ref-19010) article in the ENGINE PERFORMANCE Section.

CODE 13: INTAKE AIR TEMPERATURE SENSOR

Note. Intake air temperature sensor is built into airflow sensor. For CODE 13 test purposes, airflow sensor will be referred to as intake air temperature sensor. For component terminal identification, see AIRFLOW SENSOR under TERMINAL IDENTIFICATION . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

1. If using scan tester, go to step 3). Disconnect Intake Air Temperature (IAT) sensor connector. Using a thermometer, check engine compartment ambient temperature. Using DVOM, check resistance between IAT sensor terminals nO. 5 & 6. Resistance should be 6000 ohms at 32°F (0°C), 2700 ohms at 68°F (20°C) or 400 ohms at 176°F (80°C). If resistance is not as specified, replace IAT sensor. If resistance is as specified, go to next step.
2. Using a hair dryer, warm IAT sensor while monitoring DVOM. Resistance should decrease evenly as temperature rises. If resistance remains unchanged, replace IAT sensor. If resistance changes, go to step 4).
3. Turn ignition switch to ON or RUN position. Using a thermometer, check engine compartment ambient temperature. Using scan tester, read Intake Air Temperature (IAT) sensor temperature. See «IAT SENSOR TEMPERATURE»(ref-18964-S14558292432001010800000) table. If temperatures are not as specified, replace IAT sensor. If temperatures are as specified, go to next step. IAT SENSOR TEMPERATURE Ambient Temperature Standard Value -4°F (-20°C) -20°C 32°F (0°C) 0°C 68°F (20°C) 20°C 104°F (40°C 40°C 176°F (80°C) 80°C
4. Disconnect IAT sensor connector. Using DVOM, check for continuity between chassis ground and IAT sensor connector terminal No. 5. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
5. With IAT sensor connector and ECM connector disconnected, check for continuity between IAT sensor connector terminal No. 6 and ECM connector terminal No. 52. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
6. Turn ignition switch to ON position. Check voltage between chassis ground and IAT sensor connector terminal No. 6. If voltage is not 4.5-4.9 volts, replace ECM. If voltage is as specified, replace IAT sensor.

CODE 14: THROTTLE POSITION SENSOR

Note. For component terminal identification, see TERMINAL IDENTIFICATION . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

1. If using scan tester, go to step 3). Disconnect Throttle Position Sensor (TPS) connector. Using DVOM, check resistance between TPS terminals No. 1 & 4. If resistance is not 3500-6500 ohms, replace TPS. If resistance is as specified, go to next step.
2. Check resistance between TPS terminals No. 2 & 4. While monitoring DVOM, slowly open throttle from idle to fully open position. If resistance does not change smoothly, replace TPS. If resistance changes smoothly, go to step 4).
3. Turn ignition switch to ON position. Using scan tester, read Throttle Position Sensor (TPS) voltage. With throttle at idle, voltage should read .3-1.0 volt. Voltage should increase while slowly opening throttle. At wide open throttle, voltage should read 4.5-5.5 volts. If voltage is not as specified, replace TPS. If voltage is as specified, go to next step.
4. Disconnect TPS connector. Turn ignition switch to ON position. Using DVOM, check voltage between chassis ground and TPS connector terminal No. 4. If voltage is not 4.8-5.2 volts, repair wiring harness as necessary. If voltage is as specified, go to next step.
5. Check continuity between chassis ground and TPS connector terminal No. 5. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
6. With TPS connector and ECM connector disconnected, check for continuity between TPS connector terminal No. 2 and ECM connector terminal No. 61. If continuity does not exist, repair wiring harness as necessary. If continuity exists, condition required to set trouble code is not present at this time. Test is complete. Intermittent problem may exist. See «TESTS W/O CODES»(ref-19010) article in the ENGINE PERFORMANCE Section.

CODE 21: ENGINE COOLANT TEMPERATURE (ECT) SENSOR

Note. For component terminal identification, see TERMINAL IDENTIFICATION . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

1. If using scan tester, go to step 2). Remove Engine Coolant Temperature (ECT) sensor from intake manifold. Submerge temperature sensing portion of ECT sensor in hot water. Using DVOM, check resistance across ECT sensor terminals. See «ECT SENSOR RESISTANCE SPECIFICATIONS»(ref-18964-S24321426122001010800000) table. If resistance is not as specified, replace ECT sensor. If resistance is as specified, go to step 3). ECT SENSOR RESISTANCE SPECIFICATIONS Water Temperature Approximate Ohms 32°F (0°C) 5800 68°F (20°C) 2400 104°F (40°C) 1100 176°F (80°C) 300
2. Turn ignition switch to ON or RUN position. Using a thermometer, check engine compartment ambient temperature. Using scan tester, read Engine Coolant Temperature (ECT) sensor voltage. See «ECT SENSOR VOLTAGE SPECIFICATIONS»(ref-18964-S02209561672001010800000) table. If voltage is not within specifications, replace ECT sensor. If voltage is within specification, go to next step. ECT SENSOR VOLTAGE SPECIFICATIONS Ambient Temperature Standard Value: °F (°C) -4°F (-20°C) -20°C 32°F (0°C) 0°C 68°F (20°C) 20°C 104°F (40°C 40°C 176°F (80°C) 80°C
3. Disconnect ECT sensor connector. Using DVOM, check continuity between chassis ground and connector terminal No. 2. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
4. Disconnect ECT sensor connector and ECM connector. Check continuity between ECT sensor connector terminal No. 1 and ECM connector terminal No. 63. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
5. Turn ignition switch to ON position. Check voltage between chassis ground and ECT sensor connector terminal No. 2. If voltage is not 4.5-4.9 volts, replace ECM. If voltage is as specified, condition required to set trouble code is not present at this time. Test is complete. Intermittent problem may exist. See «TESTS W/O CODES»(ref-19010) article in the ENGINE PERFORMANCE Section.

CODE 22: CRANKSHAFT POSITION (CKP) SENSOR

Note. For component terminal identification, see TERMINAL IDENTIFICATION . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

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. If using a scan tester, go to step 3).

Scheme 27

1. If using a scan tester, go to step 3). Using engine analyzer with oscilloscope capability, connect special patterns probe to connector terminal No. 2 (DOHC) or terminal No. 3 (SOHC).
2. Start engine. Compare oscilloscope wave pattern with known-good wave pattern. (Scheme 27) Verify that wave length (time) decreases as engine RPM increases. If a wave pattern is output and it fluctuates to left or right, check for loose timing belt or an abnormality in sensor pick-up disc. If a rectangular wave pattern is output even when engine is not started, substitute known-good CKP sensor. Repeat test. If wave pattern is still abnormal, go to step 5).
3. Connect an engine tachometer. Crank engine. Ensure ignition coil primary current toggles on and off. Using tachometer and scan tester, compare cranking speed and scan tester read out. If engine fails to start and tachometer reads zero RPM when engine is cranked, check for broken timing belt or faulty CKP sensor. If CKP sensor is suspected, substitute known-good CKP sensor. Repeat test procedure. If engine fails to start, tachometer reads zero RPM, and ignition coil primary current fails to toggle on and off, check for faulty ignition coil, ignition circuit or power transistor. If engine starts and readouts agree, go to next step.
4. Ensure A/C switch is in ON position to activate closed throttle position switch. Allow engine to idle. Check coolant temperature. Using scan tester, read idle speed. See «IDLE RPM SPECIFICATIONS»(ref-18964-S09991374842001010800000) table. If RPM is not to specification, check for faulty coolant temperature sensor, basic idle speed adjustment, or idle air control motor. If RPM is within specifications, go to next step. IDLE RPM SPECIFICATIONS Coolant Temperature Engine RPM -4°F (-20°C) 1280-1480 32°F (0°C) 1220-1420 68°F (20°C) 1100-1300 104°F (40°C) 950-1150 176°F (80°C) SOHC 650-850 DOHC 700-900
5. Disconnect CKP/CMP sensor connector. Turn IG switch to ON position. Using DVOM, check voltage between chassis ground and CKP/CMP sensor connector terminal No. 2 (SOHC) or terminal No. 3 (DOHC). If battery voltage does not exist, repair ignition circuit between CKP/CMP sensor connector and IG switch. If battery voltage exists, go to next step.
6. With CKP/CMP sensor connector disconnected, check for continuity between chassis ground and CKP/CMP sensor connector terminal No. 1. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
7. With CKP/CMP sensor connector and ECM connector disconnected, check for continuity between CKP/CMP sensor connector terminal No. 1 (DOHC) or terminal No. 3 (SOHC) and ECM connector terminal No. 69. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
8. With ignition switch in ON position, check for voltage between chassis ground and CKP/CMP sensor connector terminal No.2 (DOHC) or terminal No. 3 (SOHC). If 4.8-5.2 volts do not exist, replace ECM. If voltage is to specification and CKP sensor is suspected, replace CKP sensor.

CODE 23: CAMSHAFT POSITION SENSOR

Note. For component terminal identification, see TERMINAL IDENTIFICATION . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

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. Manufacturer does not provide procedures for testing component using a scan tester.

Scheme 28

1. Using engine analyzer with oscilloscope capability, connect special patterns probe to connector terminal No. 2 (DOHC) or terminal No. 4 (SOHC).
2. Start engine. Compare oscilloscope wave pattern with known-good wave pattern. (Scheme 28) Verify that wave length (time) decreases as engine RPM increases. If a wave pattern is output and it fluctuates to left or right, check for loose timing belt or an abnormality in sensor pick-up disc. If a rectangular wave pattern is output even when engine is not started, substitute known-good CMP sensor. Repeat test. If wave pattern is still abnormal, go to next step.
3. Disconnect CKP/CMP sensor connector. Turn ignition switch to ON position. Using DVOM, check voltage between chassis ground and CKP/CMP sensor connector terminal No. 2 (SOHC) or terminal NO. 3 (DOHC). If battery voltage does not exist, repair ignition circuit between CKP/CMP sensor connector and IG switch. If battery voltage exists, go to next step.
4. With CKP/CMP sensor connector disconnected, check for continuity between chassis ground and CKP/CMP sensor connector terminal No. 1. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
5. With CKP/CMP sensor connector and ECM connector disconnected, check for continuity between specified CKP/CMP sensor connector terminal and ECM connector terminal. See «ECM-TO-CKP/CMP CONNECTOR TERMINAL IDENTIFICATION»(ref-18964-S07108437712001010800000) table. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step. ECM-TO-CKP/CMP CONNECTOR TERMINAL IDENTIFICATION Application CKP/CMP Terminal No. ECM Terminal No. DOHC 2 68 SOHC 4 68
6. With ignition switch in ON position, check for voltage between chassis ground and CKP/CMP sensor connector terminal No. 2 (DOHC) or terminal No. 4 (SOHC). If 4.8-5.2 volts do not exist, replace ECM. If voltage is as specified, condition required to set trouble code is not present at this time. Test is complete. Intermittent problem may exist. See «TESTS W/O CODES»(ref-19010) article in the ENGINE PERFORMANCE Section.

CODE 24: VEHICLE SPEED SENSOR

Note. For component terminal identification, see TERMINAL IDENTIFICATION . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

Scheme 29

1. Manufacturer does not provide Vehicle Speed Sensor (VSS) testing procedures using scan tester. VSS is located at end of speedometer cable in transmission. Remove VSS. Connect battery, resistor (3-10 ohms) and voltmeter to indicated terminals. (Scheme 29) Ensure voltage pulses 4 times per speedometer shaft revolution. If voltage is not as specified, replace VSS. If voltage is as specified, go to next step.
2. Disconnect ECM connector. Using DVOM, check continuity between chassis ground and ECM connector terminal No. 66. Move vehicle. Ensure continuity pulses on and off 4 times per tire revolution. If continuity is as specified, conditions required to set code are not present at this time, test is complete. If continuity is not as specified, go to next step.
3. With VSS connector disconnected, check for continuity between chassis ground and VSS connector terminal No. 16. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
4. With VSS connector and ECM connector disconnected, turn ignition switch to ON position. Using DVOM, check for voltage between chassis ground and VSS connector terminal No. 9. If voltage is not 4.5-4.9 volts, replace ECM. If voltage is as specified, condition required to set trouble code is not present at this time. Test is complete. Intermittent problem may exist. See «TESTS W/O CODES»(ref-19010) article in the ENGINE PERFORMANCE Section.

CODE 25: BAROMETRIC PRESSURE SENSOR

Note. Barometric (BARO) pressure sensor is built into airflow sensor. For code 25 test purposes, the airflow sensor will be referred to as the BARO pressure sensor. For component terminal identification, see AIRFLOW SENSOR under TERMINAL IDENTIFICATION . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

1. Manufacturer does not provide component testing procedure without scan tester. Turn ignition switch to ON position. Using scan tester, read sensor pressure. See «BARO PRESSURE SENSOR SPECIFICATIONS»(ref-18964-S22476105452001010800000) table. If pressure is not as specified, replace BARO pressure sensor. If pressure is as specified, go to next step. BARO PRESSURE SENSOR SPECIFICATIONS Altitude: Ft. (M) Pressure: In. Hg 0 (0) 29.92 1969 (600) 27.95 3937 (1200) 25.98 5906 (1800) 24.02
2. Disconnect BARO pressure sensor connector. Using DVOM, check for continuity between chassis ground and BARO pressure sensor connector terminal No 1. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
3. With BARO pressure sensor connector disconnected, turn ignition switch to ON position. Check for voltage between chassis ground and BARO pressure sensor connector terminal No. 1. If voltage is not 4.8-5.2 volts, repair wiring harness as necessary. If voltage is as specified, go to next step.
4. With BARO pressure sensor connector and ECM connector disconnected, ground ECM connector terminal No. 65. Using DVOM, check for continuity between chassis ground and BARO pressure sensor connector terminal No. 1. If continuity does not exist, repair wiring harness as necessary. If continuity exists, condition required to set code is not present at this time. Test is complete. Intermittent problem may exist. See «TESTS W/O CODES»(ref-19010) article in the ENGINE PERFORMANCE Section.

CODE 31: KNOCK SENSOR

Note. For component terminal identification, see TERMINAL IDENTIFICATION . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

1. Manufacturer does not provide component testing procedure using scan tester. Disconnect knock sensor connector and ECM connector. Ground ECM connector terminal No. 58. Using DVOM, check continuity between chassis ground and knock sensor connector terminal No. 1. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
2. With knock sensor connector disconnected, check for continuity between chassis ground and knock sensor connector terminal No. 2. If continuity does not exist, repair wiring harness as necessary. If continuity exists, condition required to set code is not present at this time. Test is complete.

CODE 41: FUEL INJECTOR

Note. For component terminal identification, see TERMINAL IDENTIFICATION . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

1. Using a stethoscope or long-bladed screwdriver, listen for clicking sound from each injector while engine is running or being cranked. If no sound is heard from injector(s), check injector connections. If connections are not okay, repair connections as necessary. If connections are okay, go to next step.
2. Disconnect injector connector. Using DVOM, check resistance across injector terminals. If resistance is not 13-16 ohms, replace injector. If resistance is as specified, go to next step.
3. Using scan tester, read injector drive time while cranking engine. See «INJECTOR CRANKING DRIVE TIME SPECIFICATIONS»(ref-18964-S19617539532001010800000) table. Go to next step. INJECTOR CRANKING DRIVE TIME SPECIFICATIONS Coolant Temperature Drive Time 32°F (0°C) SOHC 18-22 ms DOHC 17-21 ms 68°F (20°C) All Models 35-43 ms 176°F (80°C) SOHC 8.9-10.9 ms DOHC 8.6-10.6 ms
4. Ensure coolant temperature is at 176-205°F (80-95°C), all accessories are off and transaxle is in Neutral position. Using scan tester, read injector drive time under specified engine conditions. See «INJECTOR OPERATING DRIVE TIME SPECIFICATIONS»(ref-18964-S00306423732001010800000) table. Go to next step. INJECTOR OPERATING DRIVE TIME SPECIFICATIONS Engine State Drive Time 750 RPM SOHC 2.4-3.6 ms DOHC 2.6-3.8 ms 2000 RPM All Models 2.0-3.2 ms Suddenly Accelerated (1) (1) Drive time should increase.
5. Allow engine to idle after warm up. Using scan tester, shut off injectors in sequence. Idle should change when good injectors are shut off. If idle state does not change, check injector connection, spark plug and cable, and cylinder compression. If conditions are not as specified in preceding steps, go to next step.
6. Disconnect MFI relay connector and injector connector at faulty injector. Using DVOM, check for continuity between MFI relay connector terminal No. 2 and injector connector terminal No. 1. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
7. Using a DVOM, check for continuity between injector connector terminal No. 2, and specified ECM connector terminal. See «INJECTOR-TO-ECM CIRCUIT IDENTIFICATION»(ref-18964-S10628048632001010800000) table. If continuity does not exist, repair wiring harness as necessary. If continuity exists, condition required to set code is not present at this time. Intermittent problem may exist. See «TESTS W/O CODES»(ref-19010) article in the ENGINE PERFORMANCE Section. INJECTOR-TO-ECM CIRCUIT IDENTIFICATION Application Injector No. ECM Terminal No. All Models 1 1 2 14 3 2 4 15
8. Disconnect injector connector at faulty injector. Turn ignition switch to ON position. Using DVOM, check for voltage between chassis ground and injector connector terminal No. 1. If battery voltage does not exist, repair wiring harness as necessary. If battery voltage exists, go to next step.
9. With injector connector disconnected, disconnect ECM connector. Check for continuity between injector connector terminal No. 2 and ECM connector terminal No. 1 for injector No. 1, No. 14 for injector No. 2, No. 2 for injector No. 3, or No. 15 for injector No. 4. If continuity does not exist, repair wiring harness as necessary. If continuity exists, condition required to set code is not present at this time. Test is complete. Intermittent problem may exist. See «TESTS W/O CODES»(ref-19010) article in the ENGINE PERFORMANCE Section.

CODE 43: EGR TEMPERATURE SENSOR

Note. For component terminal identification, see TERMINAL IDENTIFICATION . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

1. If using scan tester, go to step 2). Remove EGR temperature sensor from intake manifold. Submerge temperature sensing portion of EGR temperature sensor in hot water. Using DVOM, check resistance across sensor terminals. Resistance should be 60,000-83,000 ohms at 122°F (50°C), 11,000-14,000 at 212°F (100°C). If resistance is not as specified, replace EGR temperature sensor. If resistance is as specified, go to step 3).
2. Warm engine to operating temperature. Allow engine to idle for 2 minutes. Squeeze green-striped hose between EGR valve and EGR solenoid. Using scan tester, read EGR temperature sensor temperature. At 700-750 RPM, scan tester should read 70°F (158°C) or less. At 3500-4000 RPM, scan tester should read 158°F (70°C) or more. If reading is not as specified, replace EGR temperature sensor. If reading is as specified, go to next step.
3. Disconnect EGR temperature sensor connector. Using DVOM, check continuity between chassis ground and EGR temperature sensor terminal No. 1. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
4. With EGR temperature sensor connector and ECM connector disconnected, turn ignition switch to ON position. Check voltage between chassis ground and EGR connector terminal No. 2. Voltage should be 3.3-4.7 volts. If voltage is not as specified, replace ECM. If voltage is as specified, condition required to set code is not present at this time. Test is complete. Intermittent problem may exist. See «TESTS W/O CODES»(ref-19010) article in the ENGINE PERFORMANCE Section.

CODES 44, 52 & 53: IGNITION COILS

Note. For component terminal identification, see TERMINAL IDENTIFICATION . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

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.

Scheme 30

1. Using scan tester, go to step 3). Disconnect power transistor connector. Install Test Harness (MB991348 ) between transistor and connector. Start engine and accelerate to 1200 RPM. Using engine analyzer with oscilloscope capability, sequentially connect special pattern probe to ignition power transistor connector terminals No. 2 (coils No. 2 and No. 3), and No. 7 (coils No. 1 and No. 4). Observe oscilloscope wave pattern at each terminal. (Scheme 30) Go to next step.
2. If oscilloscope wave pattern rise fluctuates to right and is between 2-4.5 volts for each transistor terminal, system is okay. If wave pattern is rectangular and is 2 volts or less, check for broken wire in primary ignition circuit. If wave pattern is rectangular and is 12 volts or more, replace defective ignition power transistor.
3. Using scan tester, check for continuity between chassis ground and ignition timing adjustment terminal (located at firewall). With engine at idle, ground ignition timing adjustment terminal. Scan tester should display ON. With ignition timing adjustment terminal not grounded, scan tester should display OFF. If conditions are not as specified, repair circuit between ignition timing adjustment connector and ECM terminal No. 34. If conditions are as specified, go to next step.
4. Connect timing light and tachometer. Ensure engine is at normal operating temperature. With engine at idle (750-850 RPM), check ignition timing. Timing should be 0-16 degrees BTDC. Go to next step.
5. With engine at 2000 RPM, timing should be 22-42 degrees BTDC. Ground ignition timing adjustment terminal. With engine idling, ignition timing should be 2-8 degrees BTDC. Go to next step.
6. Disconnect ECM connector. Sequentially ground ECM connector terminals No. 10 (coils No. 2 and No. 3) and No. 23 (coils No. 1 and No. 4). Check for continuity between chassis ground and ignition power transistor connector terminals No. 2 (coils No. 2 and No. 3) and No. 7 (coils No. 1 and No. 4). If continuity does not exist,check appropriate circuit for open or short to ground between ignition power transistor and ECM. If continuity exists, go to next step.
7. Disconnect ignition power transistor connector. Turn ignition switch on. Sequentially check voltage between chassis ground and ignition power transistor connector terminals No. 1 and No. 8. If battery voltage is not present, repair appropriate circuit between ignition power transistor and ignition switch. If battery voltage is present, go to next step.
8. With ignition switch in START position, Sequentially check voltage between chassis ground and ignition power transistor connector terminals No. 2 and No. 7. Voltage should be 0.5-4.0 volts. If voltage is not as specified, repair appropriate circuit between ignition power transistor connector and ECM connector. If voltage is as specified, go to next step.
9. With ignition switch in ON position, check voltage at ignition timing adjustment connector. Voltage should be 4.0-5.2 volts. If voltage is as specified, circuit is okay. If voltage is not as specified, repair wiring between ignition timing adjustment connector and ECM connector.

CODE 55: IDLE AIR CONTROL POSITION SENSOR

Note. For component terminal identification, see TERMINAL IDENTIFICATION . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

1. Manufacturer does not provide component testing procedure without using scan tester. Ensure engine coolant temperature is 185-205°F (85-95°C). Place transmission in Park or Neutral. Turn off all accessories except A/C. Ensure A/C clutch is operating when A/C system is on. Allow engine to idle.
2. Using scan tester, read Idle Air Control (IAC) position sensor step. See «IAC POSITION SENSOR STEP SPECIFICATIONS»(ref-18964-S12402233942001010800000) table. If scan tester does not read as specified, replace IAC position sensor. If readings are as specified, go to next step. IAC POSITION SENSOR STEP SPECIFICATIONS A/C Switch Position Standard Step Value Off 2-20 On Increase From 8-50 (1) Increase From 3-40 (1) For A/T models. Brakes applied, transmission selector in "D" and A/C on.
3. Disconnect ECM connector and IAC position sensor connector. Ground specified ECM connector terminal and using DVOM, check continuity between chassis ground and specified IAC connector terminal. See «ECM-TO-IAC HARNESS CIRCUIT IDENTIFICATION»(ref-18964-S17232032472001010800000) table. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step. ECM-TO-IAC HARNESS CIRCUIT IDENTIFICATION Application ECM Terminal No. IAC Terminal No. All Models 5 4 18 2 61 1
4. With IAC position sensor connector disconnected, check continuity between chassis ground and IAC position sensor connector terminal No. 3. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
5. With IAC position sensor connector disconnected and ECM connector connected, turn ignition switch to ON position. Check for voltage between chassis ground and IAC connector terminals No. 2 and No. 4. If voltage is not 4.8-5.2 volts on either circuit, replace ECM. If voltage is as specified, go to next step.
6. Check voltage between chassis ground and IAC position sensor connector terminal No. 1. If voltage is not 4.8-5.2 volts, replace ECM. If voltage is as specified, condition required to set code is not present at this time. Test is complete. Intermittent problem may exist. See «TESTS W/O CODES»(ref-19010) article in the ENGINE PERFORMANCE Section.

CODES 59 & 69: REAR OXYGEN SENSOR (O2S)

Note. For component terminal identification, see TERMINAL IDENTIFICATION . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

1. If using scan tester, go to next step. Disconnect O2S connector. Using DVOM, check continuity between O2S terminals No. 3 and No. 4. If continuity does not exist, replace O2S. If continuity exists, go to step 3).
2. With an assistant, road test vehicle. Drive vehicle with wide open throttle in 2nd gear (M/T) or "L" position (A/T). Using scan tester, read O2S voltage. If O2S voltage is not .6-1.0 volt at 3500 RPM, replace O2S. If voltage is as specified, go to next step.
3. Disconnect O2S connector and MFI relay connector. Using DVOM, check for continuity between O2S connector terminal No. 3 and MFI relay connector No. 2. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
4. With O2S connector disconnected, disconnect ECM connector. Check for continuity between O2S connector terminal No. 1 and ECM connector terminal No. 55. If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
5. With O2S connector disconnected, check for continuity between chassis ground and O2S connector terminals No. 2 and No. 4. If continuity does not exist on either circuit, repair wiring harness as necessary. If continuity exists and preceding test procedure did not discover any trouble codes, replace O2S.

SUMMARY

If no hard trouble codes (or only pass codes) are present, driveability symptoms exist, or intermittent codes exist, proceed to TESTS W/O CODES article in the ENGINE PERFORMANCE Section for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.