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Home >> Infiniti >> 1998 >> Q45t V8-4130cc 4.1L DOHC MFI (VH41) >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Testing and Inspection >> Initial Inspection and Diagnostic Overview >> Description of On-Board Diagnostics >> Diagnostic Test Modes >> Description of Diagnostic Modes

Description of Diagnostic Modes





The malfunction indicator lamp is located on the instrument panel.
1. The malfunction indicator lamp will light up when the ignition switch is turned ON without the engine running. This is for checking the blown lamp.
- If the malfunction indicator lamp does not light up, check the bulb and bulb circuit.
2. When the engine is started, the malfunction indicator lamp should go off.
If the lamp remains on, the on board diagnostic system has detected an engine system malfunction.

ON BOARD DIAGNOSTIC SYSTEM FUNCTION
The on board diagnostic system has the following tour functions.

Diagnostic Test Mode I
1. BULB CHECK:
This function checks the bulb for damage (blown, open circuit, etc.) of the malfunction indicator lamp.
If the MIL does not come on, check MIL circuit and ECM test mode.
2. MALFUNCTION WARNING:
This is a usual driving condition. When a malfunction is detected twice in two consecutive driving cycles (2 trip detection logic), the MIL will light up to inform the driver that a malfunction has been detected.
The following malfunctions will light up or blink the MIL in the 1st trip.
- Misfire (possible three way catalyst damage)"
- "Closed loop control"
- Fail-safe mode

Diagnostic Test Mode II
1. SELF-DIAGNOSTIC RESULTS:
This function allows 1st trip DTCs to be read.
2. FRONT HEATED OXYGEN SENSOR MONITOR:
This function allows the fuel mixture condition (lean or rich), monitored by front heated oxygen sensor, to be read.





MIL Flashing without DTC
If the ECM is in Diagnostic Test Mode II, the MIL may flash when the engine is running. In this case, check ECM test mode selector following "HOW TO SWITCH DIAGNOSTIC TEST MODES".




HOW TO SWITCH DIAGNOSTIC TEST MODES

DIAGNOSTIC TEST MODE-BULB CHECK
In this mode, the MALFUNCTION INDICATOR LAMP on the instrument panel should stay ON. If it remains OFF, check the bulb.




DIAGNOSTIC TEST MODE 1-MALFUNCTION WARNING

- These Diagnostic Trouble Code Numbers are clarified in Diagnostic Test Mode II (SELF-DIAGNOSTIC RESULTS).







DIAGNOSTIC TEST MODE II-SELF-DIAGNOSTIC RESULTS
In this mode, the DTC and 1st trip DTC are indicated by the number of blinks of the MALFUNCTION INDICATOR LAMP as shown below.
The DTC and 1st trip DTC are displayed at the same time. If the MIL does not illuminate in diagnostic test mode 1 (Malfunction warning), all displayed items are 1st trip DTC's. If only one code is displayed when the MIL illuminates in diagnostic test mode II (SELF-DIAGNOSTIC RESULTS), it is a DTC; it two or more codes are displayed, they may be either DTC's or 1st trip DTC's. DTC No. is same as that of 1st trip DTC. These unidentified codes can be identified by using the consult or GST A DTC will be used as an example for how to read a code.

Long (0.6 second) blinking indicates the two LH digits of number and short (0.3 second) blinking indicates the two RH digits of number. For example, the malfunction indicator lamp blinks 10 times for 6 seconds (0.6 sec 10 times) and then it blinks three times for about 1 second (0.3 sec x 3 times). This indicates the DTC "1003" and refers to the malfunction of the park/neutral position switch.
In this way, all the detected malfunctions are classified by their diagnostic trouble code numbers. The DTC "0505" refers to no malfunction.




HOW TO ERASE DIAGNOSTIC TEST MODE II (Self-diagnostic results)
The diagnostic trouble code can be erased from the backup memory in the ECM when the diagnostic test mode is changed from Diagnostic Test Mode II to Diagnostic Test Mode I. (Refer to "HOW TO SWITCH DIAGNOSTIC TEST MODES".)
- If the battery terminal is disconnected, the diagnostic trouble code will be lost from the backup memory within 24 hours.
- Be careful not to erase the stored memory before starting trouble diagnoses.
- If the security indicator lights up with the ignition switch in the "ON" position or "NATS MALFUNCTION" is displayed on "SELF-DIAG RESULTS" screen, perform self- diagnostic results mode with CONSULT using NATS program card (NATS-E960U).
- Confirm no self-diagnostic results of NATS is displayed before touching "ERASE" in "SELF-DIAG RESULTS" mode with CONSULT
- When replacing ECM, initialization of NATS system and registration of all NATS ignition key IDs must be carried out with CONSULT using NATS program card (NATSE960U).
Therefore, be sure to receive all keys from vehicle owner. Regarding the procedures of NATS initialization and NATS ignition key ID registration, refer to CONSULT operation manual, NATS.

NOTE: NATS: IPPS (Infiniti Personal Protection System)





DIAGNOSTIC TEST MODE II-FRONT HEATED OXYGEN SENSOR MONITOR
In this mode, the MALFUNCTION INDICATOR LAMP displays the condition of the fuel mixture (lean or rich) which is monitored by the front heated oxygen sensor.
To check the front heated oxygen sensor function, start engine in the Diagnostic Test Mode II and warm it up until engine coolant temperature indicator points to the middle of the gauge.
Next run engine at about 2,000 rpm for about 2 minutes under no-load conditions. Then make sure that the MALFUNCTION INDICATOR LAMP comes ON more than 5 times every 10 seconds when measured at 2,000 rpm under no-load.




How to Switch Monitored Sensor From Left Bank to Right Bank or Vice Versa

- The following procedure should be performed while the engine is running.
1. Turn diagnostic test mode selector on ECM fully clockwise.
2. Wait at least 2 seconds.
3. Turn diagnostic test mode selector on ECM fully counterclockwise.
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