On Board Diagnostic (OBD) System: Introduction
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:
DIAGNOSTIC INFORMATION REFERENCE CHART
| Emission-related diagnostic information | Diagnostic service |
|---|---|
| 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.
DTC CHART
| x: Applicable -: Not applicable | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| DTC | 1st trip DTC | Freeze Frame data | 1st trip Freeze Frame data | SRT code | SRT status | Test value | |||
| CONSULT-III | 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 illuminates 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 ".)