Description of On-Board Diagnostics

On-Board Diagnostic System Description
For automatic transmission control system, TCM has the following functions. Refer to Inspection of TCM and Its Circuits.
^ When the ignition switch is turned ON with the engine at a stop, malfunction indicator lamp (MIL) (1) turns ON to check the bulb of the MIL.
^ When TCM detects a malfunction in A/T control system (and/or a malfunction which gives an adverse effect to vehicle emission) while the engine is running, TCM requires ECM to make the malfunction indicator lamp in the meter cluster of the instrument panel turn ON. TCM stores the malfunction area (DTC according to SAE J2012) in TCM 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.)
^ It is possible to communicate through DLC (3) by using not only SUZUKI scan tool (2) but also OBD-II generic scan tool which are in compliance with SAEJ1978. (Diagnostic information can be accessed by using a scan tool.)





2 Driving Cycle Detection Logic
The malfunction detected in the first driving cycle is stored in TCM 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
TCM 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) when a malfunction was detected by checking the freeze frame data.