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 CHART
| Emission-related diagnostic information | SAE Mode |
|---|---|
| Diagnostic Trouble Code (DTC) | Service $03 of SAE J1979/ISO 15031-5 |
| Freeze Frame data | Service $02 of SAE J1979/ISO 15031-5 |
| System Readiness Test (SRT) code | Service $01 of SAE J1979/ISO 15031-5 |
| 1st Trip Diagnostic Trouble Code (1st Trip DTC) | Service $07 of SAE J1979/ISO 15031-5 |
| 1st Trip Freeze Frame data | |
| Test values and Test limits | Service $06 of SAE J1979/ISO 15031-5 |
| Calibration ID | Service $09 of SAE J1979/ISO 15031-5 |
| Permanent Diagnostic Trouble Code (Permanent DTC) | Service $0A* of SAE J1979/ISO 15031-5 |
The above information can be checked using procedures listed in the table below.
INFORMATION CHART
| x: Applicable -: Not applicable | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| DTC | 1st trip DTC | Freeze Frame data | 1st trip Freeze Frame data | SRT code | Readiness test | Test value | Permanent DTC status | |||
| SDT | x | x | x | x | x | x | - | x | ||
| GST | x | x | x | - | x | x | x | x | ||
| ECM | x | x (1) | - | - | - | x | - | - | ||
|
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When DTC and 1st trip DTC simultaneously appear on the display, they cannot be clearly distinguished from each other. 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: ECM .)