On-Board Diagnostic System
ECM in this vehicle has following functions in compliance with OBD-II regulations.
- When the ignition switch is turned ON with the engine at a stop, malfunction indicator lamp (MIL) turns ON to check the bulb of the malfunction indicator lamp.
- When ECM detects a malfunction which gives an adverse effect to vehicle emission while the engine is running, it makes the malfunction indicator lamp in the meter cluster of the instrument panel turn ON or flash (flashing only when detecting a misfire which can cause damage to the catalyst) and stores the malfunction area (DTC according to SAE J2012) in its memory.
(If it detects that continuously 3 driving cycles are normal after detecting a malfunction, however, it makes MIL turn OFF although DTC stored in its memory will remain.)
- As a condition for detecting a malfunction in some areas in the system being monitored by ECM and turning ON the malfunction indicator lamp due to that malfunction, 2 driving cycle detection logic is adopted to prevent erroneous detection.
- When a malfunction is detected, engine and driving conditions then are stored in ECM memory as freeze frame data. (For the details, refer to description on Freeze frame data.)
- It is possible to communicate by using not only SUZUKI scan tool (Tech-1) but also OBD-II generic scan tool which are in compliance with SAE J1978. (Diagnostic information can be accessed by using a scan tool.)
WARM-UP CYCLE
A warm-up cycle means that engine temperature must reach a minimum of 70°C (160°F) and rise at least 22°C (40°F) over the course of driving cycle.
DRIVING CYCLE
A "Driving Cycle" consists of engine start-up and engine shutoff.
2 DRIVING CYCLE DETECTION LOGIC
The malfunction detected in the first driving cycle is stored in ECM memory (in the form of pending DTC and freeze frame data) but the malfunction indicator lamp does not light at this time. it lights up at the second detection of same malfunction also in the next driving cycle.
PENDING DTC
Pending DTC means a DTC detected and stored temporarily at 1 driving cycle of the DTC which is detected in the 2 driving cycle detection logic.
FREEZE FRAME DATA
ECM stores the engine and driving conditions (in the form of data as shown) at the moment of the first detection of a malfunction in its memory. This data is called "Freeze frame data".
Therefore, it is possible to know engine and driving conditions (e.g., whether the engine was warm or not, whether the vehicle was running or stopped, whether air/fuel mixture was lean or rich, etc.) when a malfunction was detected by checking the freeze frame data. Its use is helpful when rechecking or diagnosing a trouble.
PRIORITY OF FREEZE FRAME DATA:
As ECM can store freeze frame data for one malfunction only, the freeze frame data shown as "61" below has a priority for storage. (If malfunction as described in the upper square "1" below is detected while the freeze frame data in the lower square "2" has been stored, the freeze frame data "2" will be updated by the freeze frame data "1".)
Freeze Frame Data:
Priority 1: Freeze frame data at initial detection of malfunction among misfire detected (P0300-P0304), fuel system too lean (P0171) and fuel system too rich (P0172)
Priority 2: Freeze frame data when a malfunction other than those in "1" above is detected
FREEZE FRAME DATA CLEARANCE:
The freeze frame data is cleared at the same time as clearance of diagnostic trouble code (DTC).
DATA LINK CONNECTOR (DLC)
DLC is in compliance with SAEJ1962 in its installation position, the shape of connector and pin assignment.
OBD-II serial data line (K line of ISO 9141) is used for SUZUKI scan tool (Tech-1) or OBD-II generic scan tool to communicate with ECM. SUZUKI serial data line is used for SUZUKI scan tool (Tech-1) to communicate with an electronic control unit other than ECM (Airbag SDM, ABS control module, etc.).