CONSULT TESTER
In addition to self-diagnostic capability, all Infiniti models are equipped with a Data Link Connector (DLC) for use with Nissan's CONSULT Tester (J-38465). On G20, DLC is located on left side behind fuse block cover.
Note. When performing BASIC TESTING, DO NOT erase any diagnostic information stored in ECM memory.
Note. CHECK ENGINE light is now referred to as Malfunction Indicator Light (MIL).
HARD FAILURES
Hard failures cause Malfunction Indicator Light (MIL) to glow and remain on until problem is repaired. If light comes on and remains on (light may flash) during vehicle operation, cause of malfunction must be determined using diagnostic code charts. If a sensor fails, control unit will use a substitute value in its calculations to continue engine operation. In this condition, commonly known as limp-in mode, vehicle runs but driveability will not be optimum.
INTERMITTENT FAILURES
Intermittent failures may cause Malfunction Indicator Light (MIL) to flicker or glow and go out after intermittent fault goes away. However, corresponding trouble code will be stored in ECM memory. Not all trouble codes will illuminate MIL. If related fault does not reoccur within a certain time frame, related trouble code will be erased from ECM memory. Intermittent failures may be caused by sensor, connector or wiring related problems. See INTERMITTENTS in TESTS W/O CODES article in the ENGINE PERFORMANCE Section.
Note. Follow proper diagnostic routine when diagnosing system. See DIAGNOSTIC ROUTINE table.
| Procedure | Order |
|---|---|
| Basic Diagnostic Procedures | 1st |
| Entering Diagnostics | 2nd |
| Retrieving Trouble Codes | 3rd |
| Symptoms (1) | 4th |
| Intermittents (1) | 5th |
| (1) Symptoms and intermittents are covered in TESTS W/O CODES article in the ENGINE PERFORMANCE Section. | |
| (1) | Symptoms and intermittents are covered in TESTS W/O CODES article in the ENGINE PERFORMANCE Section. |
DIAGNOSTIC ROUTINE
MALFUNCTION INDICATOR LIGHT (MIL)
Note. Not all trouble codes activate MIL.
All models are equipped with a Malfunction Indicator Light (MIL). As a bulb check, light glows when ignition is turned on and engine is not running.
On California models, MIL glows when a fault is detected with engine running. A corresponding trouble code will set in ECM memory. MIL also glows if ECM or crankshaft position sensor malfunctions.
On Federal models, MIL glows only when ECM or crankshaft position sensor malfunctions with engine running.
Mode I
This is normal operating mode. In this mode, Malfunction Indicator Light (MIL) and Red LED inspection light in ECM stay on when ignition is turned on, engine off (bulb check). If engine is started, MIL and Red LED in ECM should turn off, unless a fault or trouble code is present (California) or if ECM or crankshaft position sensor is malfunctioning (California and Federal).
Mode II
This is self-diagnostic mode for retrieving fault or trouble codes. See RETRIEVING CODES. With engine running, Mode II can monitor air/fuel mixture feedback control. MIL and Red LED in ECM will flash on (lean) and off (rich) more than 5 times every 10 seconds with engine speed at 2000 RPM when system is in closed loop. MIL and Red LED do not flash (remain on or off) if system is in open loop.
RETRIEVING CODES
Use Mode II to retrieve trouble codes. Read codes using either Malfunction Indicator Light (MIL) or Red LED inspection light on ECM. Trouble codes will flash after selecting Mode II.
Trouble codes are indicated by number of flashes from MIL or Red LED inspection light. For example, 3 long (.6 second) flashes followed by 2 short (.3 second) flashes of MIL or Red LED indicate a Code 32. There will be a .9 second pause between long and short flash groups. There will be a 2.1 second pause between codes.
CLEARING CODES
Note. Ensure all diagnostic codes are accessed from ECM memory before disconnecting battery or switching from Mode II to Mode I.
Memory Erase
Stored memory can be erased by disconnecting battery or selecting Mode I after Mode II has been accessed.
Final Check For All Code Charts
Unless otherwise instructed in code inspection, perform following FINAL CHECK after each repair is completed.
- Erase Diagnostic Test Mode II (Self-Diagnostic Results) memory. See «CLEARING CODES»(ref-17417-S36275760862000122900000) under SELF-DIAGNOSTIC SYSTEM.
- Ensure Code 55 (no malfunction) is displayed in self- diagnostic mode.
- Perform a test drive.
- Perform Diagnostic Test Mode II (Self-Diagnostic Results) again. If results are okay, inspection is complete. If results are not okay, verify ECM pin terminals or harness connector are not damaged.
SUMMARY
If no hard fault 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.
Check Input Signal Circuit
Turn ignition off. Disconnect ECM harness connector and A/T control unit harness connector. Verify harness continuity between ECM connector terminal No. 42 and A/T control unit connector terminal No. 10 (White/Red wire). Verify harness continuity between ECM connector terminal No. 44 and A/T control unit connector terminal No. 11 (White/Blue wire). (Scheme 67)and (Scheme 68). If continuity is present, perform FINAL CHECK. If continuity is not present, check harness and connectors between ECM and A/T control unit. Repair harness or connectors as necessary and perform FINAL CHECK.
