OBD System Description

OBD System Description

ECM in this vehicle has the following functions in compliance with OBD-II regulations.

- When the ignition mode of the keyless push start system is in "ON" while the engine stopped, ECM turns ON MIL (1) to check the MIL (1) and its circuit.
- When ECM detects a malfunction which adversely effects vehicle emission more than specified D/C, it displays message in information display (2) and turns on or flashes MIL in the combination meter (flashing only when detecting a misfire which can cause damage to the catalyst) and stores the DTC in its memory. If it detects normal conditions continuously for three driving cycles after detecting a malfunction, it turns off MIL after engine start in next D/C although DTC stored in its memory is retained as history DTC.
- For some malfunctions, ECM adopts the 2 D/C detecting logic to prevent erroneous detection. With this logic, MIL turns ON when the malfunction is detected in 2 consecutive D/Cs.
- Malfunctions detected by ECM are stored in its memory as pending DTC, confirmed DTC (current and history) and permanent DTC. The permanent DTC, among others, will be stored in the memory that cannot be manually erased. For the details, refer to description on Permanent DTC.
- When a malfunction is detected, engine and driving conditions at the moment the malfunction was detected are stored in ECM memory as freeze frame data. For the details, refer to description on Freeze Frame Data.
- SUZUKI scan tool (SUZUKI-SDT) (4) or CAN communication OBD-II generic scan tool can communicate with ECM via DLC (3).





Warm-Up Cycle

Warm-up cycle means that the coolant temperature has risen by at least 22 °C (40 °F) from engine starting and reaches a minimum temperature of at least 71 °C (160 °F).

Driving Cycle (D/C)

A "Driving Cycle" is a duration from an engine startup to the following engine shutoff.

2 Driving Cycle Detection Logic

The malfunction detected in the 1st driving cycle is stored in ECM memory (in the form of pending DTC and freeze frame data) but the MIL does not turn on at this time. It turns on at the 2nd detection of the same malfunction in the next driving cycle.

Pending DTC

Pending DTC means a DTC detected and stored temporarily at the 1st driving cycle of the 2 D/C detection logic.

Permanent DTC

In accordance with SAE J 1979, ECM stores DTCs that adversely affect vehicle emission (i.e. DTCs with MIL turning on) in non-volatile RAM (NVRAM) separately from that for pending and confirmed DTCs. This DTC is called a permanent DTC.

Unlike pending and confirmed DTCs, the permanent DTC will not be cleared even when executing the clear command of scan tool or when shutting off the power to ECM. The permanent DTC is cleared only when the ECM detects no malfunction in the trouble area of the permanent DTC. (For permanent DTC clearance, refer to DTC Clearance DTC Clearance.)

Up to four of the most recent permanent DTCs will be stored in memory. The DTCs are cleared once a full determination has been made that they are normal.

Freeze Frame Data

ECM stores the engine and driving conditions at the moment of the 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, where the vehicle was running or stopped, where air/fuel mixture was lean or rich) when a malfunction was detected by checking the freeze frame data. Also, ECM has a function to store each freeze frame data for 3 different malfunctions in the order of their detection. Utilizing this function, it is possible to know the order of detection of these malfunctions. This is helpful when rechecking or diagnosing a problem.

For details of freeze frame data that can be read from ECM, refer to table below.





NOTE:

- For freeze flame data with asterisk (*), it indicates the ratio between power supply voltage and output voltage of related sensor.
When power supply voltage is 5.0 V and output voltage is 4.0 V, freeze frame data is displayed as follows.

- For systems where the output is proportional to the input voltage, it displays 80% (= the percent of maximum input reference voltage).
- For systems where the output is inversely proportional to the input voltage, it displays 20% (=100% minus the percent of maximum input reference voltage).

- For relative TP with asterisks (**) in above table, it indicates value calculated by formula ((output voltage - output voltage at closed throttle position) / power supply voltage).
When power supply voltage is 5.0 V and output voltage at closed throttle position is 1.0 V, freeze frame data is displayed as follows.

- At closed throttle position (output voltage = 1.0 V), it displays 0%.
- At wide open throttle position (output voltage = 4.0 V), it displays 60%. However, for systems where the output is inversely proportional to the input voltage, it displays 100% minus above-mentioned formula.

Freeze flame data (for example)





Priority of freeze frame data

ECM has 4 frames where the freeze frame data can be stored. The first frame stores the freeze frame data of the malfunction which was detected first. However, the freeze frame data stored in this frame is updated according to the priority described below. (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".)





In the 2nd through the 4th frames, the freeze frame data of each malfunction is stored in the order of detection. These data are not updated.

Shown in the table below are examples of how freeze frame data are stored when two or more DTCs are detected.





-: No freeze frame data

Freeze frame data clearance

The freeze frame data is cleared at the same time as clearance of DTC.

System Readiness Test

The system readiness test is to check if the on-board diagnosis of each system related to exhaust emission has been completed or not with a scan tool (SUZUKI SDT or CAN communication OBD-II generic scan tool). When the conditions established for each system are met, ECM performs an on-board diagnosis of corresponding system and changes the status of system readiness test from "Incomplete" to "Complete".

When "Complete" status is displayed, it is maintained until the "DTC clearance" is performed with scan tool.

NOTE:

- The status of system readiness test may be changed as "incomplete" when performing the following services.

- Disconnection of battery negative cable
- Disconnection of ECM connectors
- Removal of ground cable for ECM
- Disconnection of "B/U" fuse and/or "DOME" fuse

- By utilizing this system readiness test, it is possible to confirm that all DTC confirmation procedures for each system have been completed or are incomplete. For all DTCs related to each system, refer to the table below.
- The system readiness test does not determine whether result of the on-board diagnosis is "Normal" or "Abnormal", rather it displays whether the result is "Complete" or "Incomplete".

Monitoring Item of System Readiness Test Table