On Board Diagnostic (OBD) System: Introduction
WARNING: This page is about a different car, the 2005 Nissan Xterra. However, it is still accessible from the selected car via links, so may be relevant.
The ECM has an on board diagnostic system, which detects malfunctions related to engine sensors or actuators. The ECM also records various emission-related diagnostic information including:
EMISSION-RELATED DIAGNOSTIC INFORMATION AND SAE MODE
| Emission-related diagnostic information | SAE Mode |
|---|---|
| Diagnostic Trouble Code (DTC) | Service $03 of SAE J1979 |
| Freeze Frame data Service | $02 of SAE J1979 |
| System Readiness Test (SRT) code Service | $01 of SAE J1979 |
| 1st Trip Diagnostic Trouble Code (1st Trip | DTC) Service $07 of SAE J1979 |
| 1st Trip Freeze Frame data | |
| Test values and Test limits | Service $06 of SAE J1979 |
| Calibration ID | Service $09 of SAE J1979 |
The above information can be checked using procedures listed in the table below.
PROCEDURE FOR TESTING
| x: Applicable -: Not applicable | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| DTC 1st trip DTC | Freeze Frame data | 1st trip | Freeze Frame data | SRT code | SRT status | Test value | |||
| CONSULT-II | x | x | x | x | x | x | - | ||
| GST | x | x | x | - | x | x | x | ||
| ECM | x | X(1) | - | - | - | x | - | ||
|
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The malfunction indicator lamp (MIL) on the instrument panel lights up when the same malfunction is detected in two consecutive trips (Two trip detection logic), or when the ECM enters fail-safe mode. (Refer to FAIL-SAFE CHART .)