A/T Diagnosis General Description
A/T Diagnosis General DescriptionThis vehicle is equipped with an electronic transmission control system, which control the automatic shift up and shift down timing, TCC operation, etc. suitably to vehicle driving conditions.
PCM (ECM) has an On-Board Diagnosis system which detects a malfunction in this system and abnormality of those parts that influence the engine exhaust emission.
When diagnosing a trouble in the transmission including this system, be sure to have full understanding of the outline of "On-Board Diagnostic System Description:" and each item in "Precautions in Diagnosing Trouble:" "Precautions in Diagnosing Trouble" and execute diagnosis according to "A/T System Check:" to obtain correct result smoothly.
On-Board Diagnostic System Description
For automatic transmission control system, PCM has the following functions. Refer to "Inspection of ECM (PCM) and its Circuits:".
^ 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 MIL.
^ When PCM 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, it makes the malfunction indicator lamp in the meter cluster of the instrument panel turn ON 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)
^ It is possible to communicate through DLC by using not only SUZUKI scan tool 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
Refer to "On-Board Diagnostic System Description:".
Pending DTC
Refer to "On-Board Diagnostic System Description:".
Freeze Frame Data
Refer to "On-Board Diagnostic System Description:".
Precautions in Diagnosing Trouble
^ Don't disconnect couplers from PCM, battery cable from battery, PCM ground wire harness from engine or main fuse before checking the diagnostic information (DTC, freeze frame data, etc.) stored in PCM memory. Such disconnection will clear memorized information in PCM memory.
^ Using SUZUKI scan tool or OBD-II generic scan tool, the diagnostic information stored in PCM memory can be checked and cleared as well. Before its use, be sure to read Operator's (Instruction) Manual supplied with it carefully to have good understanding of its functions and usage.
^ Priorities for diagnosing troubles:
If two or more DTCs are stored, proceed to the diagnostic procedure of the DTC which was detected earliest in the order and follow the instruction in that procedure.
If no instructions are given, troubleshoot diagnostic trouble codes according to the following priorities.
- DTCs other than DTC P0171/P0172/P0174/P0175 (Fuel system too lean/too rich), DTC P0300/P0301/P0302/P0303/P0304/P0305/P0306 (Misfire detected) and DTC P0401/P0402 (EGR flow Insufficient Detected/Excessive Detected)
- DTC P0171/P0172/P0174/P0175 (Fuel system too lean/too rich) and DTC P0401/P0402 (EGR flow Insufficient Detected/Excessive Detected)
- DTC P0300/P0301/P0302/P0303/P0304/P0305/P0306 (Misfire detected)
^ Be sure to read "Precautions for Electrical Circuit Service:" before inspection and observe what is written there.
^ PCM replacement:
When substituting a known-good PCM, check for the following conditions.
Neglecting this check may result in damage to a good PCM.
- All relays and actuators have resistance of specified value.
- MAF sensor, Manifold absolute pressure (MAP) sensor, TP sensor and fuel tank pressure sensor are in good condition. Also, the power circuit of these sensors is not shorted to the ground.