Engine Controls - Tests W/codes: Diagnosis Infiniti G20 I

SELF-DIAGNOSTIC SYSTEM

Self-diagnostic system is used for diagnosing malfunctions of Electronic Concentrated Control System (ECCS) sensors and actuators. Electronic Control Module (ECM) has 2 available diagnostic modes. Before entering self-diagnostics, perform BASIC TESTING. This prevents wasted diagnostic time and invalid diagnostic results.

DIAGNOSTIC MODES

Self-diagnostic system can detect ECCS malfunctions and store related trouble codes. Intermittent codes are also stored. All codes are stored until cleared from memory. If an intermittent does not reoccur within 50 ignition key cycles, it will be cleared from memory.

Switching modes is not possible when engine is running. During diagnosis, self-diagnostic system will automatically return to Mode I from Mode II when ignition is turned off.

ENTERING SELF-DIAGNOSTICS

1. Turn ignition on, but leave engine off. Using a small screwdriver, turn diagnostic mode selector on ECM fully clockwise. Wait at least 2 seconds, and then turn diagnostic mode selector fully counterclockwise. Mode II self-diagnostics will result, and MIL and Red LED inspection light will flash codes (if present).
2. If engine is started at this stage, MIL and Red LED inspection light will display condition of air/fuel mixture, monitored by HO2S sensor, whether system is in closed or open loop.

Note. Turn back diagnostic mode selector to fully counterclockwise position whenever vehicle is in use. Switching modes is not possible when engine is running.

TROUBLE CODE DEFINITION

Note. When DTC tests indicate to check a component, see indicated component in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. For Diagnostic Trouble Code (DTC) illustration symbol identification (Scheme 29) To identify ECM connector terminals, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

TROUBLE CODE IDENTIFICATION

Scheme 29

DIAGNOSTIC TROUBLE CODE (DTC) TESTING (G20)

Note. Procedures using Nissan CONSULT Tester (J-38465) will be shown when available. If CONSULT Tester is not available, disregard steps using CONSULT Tester and use alternate test procedure.

DTC 14: VEHICLE SPEED SENSOR (VSS)

1. Check Speedometer Operation - Verify speedometer operates properly. If speedometer operates properly, go to next step. VSS is built into speedometer. If speedometer does not operate properly, remove combination meter. Turn speedometer slowly with a small screwdriver. VSS continuity exists 2 times for each rotation of speedometer, at combination meter terminals No. 14 and 15.
2. Check Input Signal Circuit - Turn ignition off and disconnect ECM harness connector and combination meter harness connector. Check harness continuity between ECM terminal No. 32 and combination meter terminal "b" (Yellow/Green wire). see scheme 2, see scheme 3 and (Scheme 30). If continuity is not present, repair harness or connectors as necessary and perform «FINAL CHECK»(ref-17417-S28948843272000122900000).

Scheme 30

Scheme 31

Scheme 32

Scheme 33

Scheme 34

Scheme 35

1. Check Power Supply - Start engine. If engine starts, go to step 5). If engine does not start, turn ignition off. Disconnect ignition coil harness connector. Turn ignition on. Measure voltage between ignition coil harness connector terminal "a" (Black/Red wire) and ground. (Scheme 31)and (Scheme 32). If battery voltage is present, go to next step. If battery voltage is not present, check Black/Red wire circuit continuity between ignition coil and ignition switch.
2. Check Ground Circuit - Turn ignition off and disconnect power transistor harness connector. Verify harness continuity between ignition coil connector terminal "b" and power transistor connector terminal "e" (Green/Yellow wire), and between power transistor connector terminal "d" (Black wire) and engine ground. (Scheme 33)and (Scheme 34). If continuity is present, go to next step. If continuity is not present, repair harness or connectors as necessary.
3. Check Output Signal Circuit - Turn ignition off and disconnect ECM harness connector. Verify harness continuity between ECM terminal No. 1 and power transistor connector terminal "c" (White wire). (Scheme 35) If continuity is present, go to next step. If continuity is not present, repair harness or connectors as necessary.
4. Check Component - Inspect ignition coil and power transistor. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. Replace ignition coil and/or power transistor if necessary and perform «FINAL CHECK»(ref-17417-S28948843272000122900000).
5. Check Input Signal Circuit - Turn engine off. Disconnect ignition coil harness connector and resistor and condenser 4-pin connector. Disconnect ECM harness connector. Verify harness continuity between ignition coil connector terminal "b" and resistor and condenser connector terminal "f" (Green/Yellow wire), and between ECM terminal No. 3 and resistor and condenser connector terminal "g" (Yellow/Red wire). (Scheme 36)and (Scheme 37). If continuity is present, go to next step. If continuity is not present, repair harness or connectors as necessary.
6. Check Component - Inspect resistor and condenser. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. Replace resistor and condenser if necessary and perform «FINAL CHECK»(ref-17417-S28948843272000122900000).

Scheme 36

Scheme 37

DTC 31: ECM

Turn ignition on. Erase Diagnostic Test Mode II (Self-Diagnostic Results) memory. Perform Diagnostic Test Mode II (Self-Diagnostic Results). If ECM displays DTC 31 again, replace ECM.

Scheme 38

Scheme 39

Scheme 40

Scheme 41

1. Check Vacuum Source To EGR Valve - Start engine and bring to operating temperature. With engine speed at about 2000 RPM, disconnect vacuum hose to EGR valve. (Scheme 38) If vacuum is not present, go to next step. If vacuum is present, inspect EGR valve and EGR Control-BPT valve. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. Replace EGR valve and/or EGR Control-BPT valve if necessary and perform «FINAL CHECK»(ref-17417-S28948843272000122900000).
2. Check Control Function - If vacuum is not present, with engine running, measure voltage between ECM terminal No. 105 (Purple wire) and ground. At 4000 RPM, voltage should be.6-.8 volts. At 2000 RPM, voltage should be battery voltage. (Scheme 39) If voltage measured is not as specified, go to next step. If voltage is as specified, inspect vacuum hose for clogging, cracks or proper connection. Repair vacuum hose as necessary.
3. Check Output Signal Circuit - Turn engine off and disconnect ECM harness connector. Disconnect EGR and canister control solenoid valve harness connector. Verify harness continuity between ECM terminal No. 105 (Purple wire) and ground, and EGR and canister control solenoid valve harness connector terminal "a" (Purple wire) and ground. (Scheme 40)and (Scheme 41). If continuity does not exist, go to next step. If there is continuity, repair harness or connectors between ECM, EGR and canister control solenoid valve, as necessary.
4. Check Component - Inspect EGR and canister control solenoid valve. See I -SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. Measure resistance of EGR temperature sensor. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. Replace EGR and canister control solenoid valve and/or EGR temperature sensor if necessary and perform «FINAL CHECK»(ref-17417-S28948843272000122900000).
5. Check Component Using CONSULT - Turn ignition off and connect CONSULT. Connect ECM harness connector and EGR and canister control solenoid valve harness connector. Turn ignition on. Using CONSULT, perform EGRC SOL/V CIRCUIT in FUNCTION TEST mode. Replace EGR and canister control solenoid valve if necessary. Another method is to turn EGR and canister control solenoid valve ON and OFF using CONSULT in ACTIVE TEST mode. Replace EGR and canister control solenoid valve if operating sounds are not heard. Perform «FINAL CHECK»(ref-17417-S28948843272000122900000).

Scheme 42

Scheme 43

Scheme 44

1. Check Input Signal Circuit - Turn ignition off and disconnect HO2S harness connector and ECM harness connector. Verify harness continuity between ECM connector terminal No. 19 and HO2S connector terminal "b" (White wire). (Scheme 42)and (Scheme 43). If continuity is present, go to next step. If continuity is not present, repair harness or connectors as necessary.
2. Check Voltage - Connect HO2S harness connector and ECM harness connector. Bring engine to operating temperature and hold speed at approximately 2000 RPM. Using an analog voltmeter, measure voltage between ECM terminal No. 19 (White wire) and ground. (Scheme 44) If voltage measured is approximately.3 volt and there are no voltage fluctuations, replace HO2S. If voltage fluctuates between approximately.2-.9 volt, HO2S is okay. Perform «FINAL CHECK»(ref-17417-S28948843272000122900000).
3. Check Voltage Using CONSULT - Turn ignition off. Connect CONSULT, HO2S harness connector and ECM harness connector. With engine at operating temperature and speed held at 2000 RPM, select DATA MONITOR mode with CONSULT. Touch RECORD. Check EXH GAS SEN voltage. If voltage displayed is approximately.3 volt and there are no voltage fluctuations, replace HO2S. If voltage displayed fluctuates between approximately.2-.9 volt, HO2S is okay. Perform «FINAL CHECK»(ref-17417-S28948843272000122900000).

DTC 34: KNOCK SENSOR

1. Check Input Signal Circuit - Turn ignition off. Disconnect ECM harness connector and knock sensor harness connector. Verify harness continuity between knock sensor connector terminal "b" (White wire) and ECM terminal No. 27. see scheme 2, (Scheme 45) and (Scheme 46). If continuity is present, go to next step. If continuity is not present, repair harness or connectors as necessary.
2. Check Component - Inspect knock sensor. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. Replace knock sensor if necessary and perform «FINAL CHECK»(ref-17417-S28948843272000122900000).

Scheme 45

Scheme 46

Scheme 47

Scheme 48

1. Check Power Supply - Turn ignition off and disconnect EGR temperature sensor harness connector. Turn ignition on. Measure voltage between EGR temperature sensor connector terminal "a" (Blue wire) and ground. (Scheme 47)and (Scheme 48). If voltage is approximately 5 volts, go to next step. If voltage is not as specified, repair harness or connectors as necessary.
2. Check Ground Circuit - Turn ignition off. Verify harness continuity between EGR temperature sensor connector terminal "b" (Black wire) and engine ground. (Scheme 49) If continuity is present, go to next step. If continuity is not present, repair harness or connectors as necessary.
3. Check Component - Inspect EGR temperature sensor. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. Replace EGR temperature sensor if necessary and perform «FINAL CHECK»(ref-17417-S28948843272000122900000).

Scheme 49

Scheme 50

Scheme 51

1. Check Power Supply - Turn ignition off and disconnect TPS harness connector. Turn ignition on. Measure voltage between TPS connector terminal "a" (Red/Yellow wire) and ground. (Scheme 50)and (Scheme 51). If voltage is approximately 5 volts, go to next step. If voltage is not as specified, repair harness or connectors as necessary.
2. Check Ground Circuit - Turn ignition off. Verify harness continuity between TPS connector terminal "c" (Black wire) and engine ground. (Scheme 52) If continuity is present, go to next step. If continuity is not present, repair harness or connectors as necessary.
3. Check Input Signal Circuit - Disconnect ECM harness connector. see scheme 2 Verify harness continuity between ECM connector terminal No. 20 (White wire) and TPS connector terminal "b". (Scheme 53) If continuity is present, go to next step. If continuity is not present, repair harness or connectors as necessary.
4. Check Component - Inspect TPS. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. Replace TPS if necessary and perform «FINAL CHECK»(ref-17417-S28948843272000122900000).

Scheme 52

Scheme 53

Scheme 54

1. Clear Self-Learning Data - Start engine and bring to operating temperature. Stop engine and disconnect Mass Airflow (MAF) sensor connector. Start engine and run for at least 30 seconds at 2000 RPM. Stop engine and connect MAF sensor connector. Verify DTC 12 is displayed in Diagnostic Test Mode II. Erase self-diagnosis memory. Verify DTC 55 is displayed in Diagnostic Test Mode II. (Scheme 54)
2. Clear Self-Learning Data Using CONSULT - Select SELF-LEARNING CONT in ACTIVE TEST mode with CONSULT. Clear self-learning control coefficient by touching CLEAR.
3. Perform Diagnostic Test Mode II (Self-Diagnostic Results) - If DTC does not return, inspection is completed. If DTC 45 displays, relieve fuel pressure and remove injector assembly. See N - REMOVE/INSTALL/OHAUL article in the ENGINE PERFORMANCE Section. Do not remove fuel hose or injector from injector gallery. Turn ignition on. Verify fuel does not drip from injector(s). Replace any injector(s) that drip fuel. Perform «FINAL CHECK»(ref-17417-S28948843272000122900000).