Precautions In Diagnosing Trouble

Precautions in Diagnosing Trouble
^ Do not disconnect couplers from TCM, battery cable from battery, TCM ground wire harness from engine or main fuse before checking the diagnostic information (DTC, freeze frame data, etc.) stored in TCM memory. Such disconnection will clear memorized information in TCM memory.
^ Diagnostic information stored in TCM memory can be cleared as well as checked by using SUZUKI scan tool or OBD-II generic scan tool. Before using scan tool, read its Operator's (Instruction) Manual carefully to have good understanding as to what functions are available and how to use it.
It is indistinguishable which module turns on MIL because not only ECM but also TCM turns on MIL. Therefore, check both ECM and TCM for DTC when MIL lights on. When checking TCM for DTC, keep in mind that DTC is displayed on the scan tool as follows depending on the scan tool used.
- SUZUKI scan tool displays DTC detected by TCM.
- OBD-II generic scan tool displays DTC detected by each of ECM and TCM simultaneously.
^ Not using scan tool, the DTC stored in TCM memory also can be checked and cleared. DTC stored in the TCM memory is outputted by flashing of "O/D OFF" lamp with diagnosis terminal of monitor connector grounded. If no DTC is stored in TCM memory, DTC No. 12 is outputted repeatedly. If one or more DTCs are stored in TCM memory, they are outputted starting from smallest code number in increasing order. After all DTCs are outputted, all DTCs are outputted repeatedly.
^ When replacing TCM with used one, all learned controls which are stored in TCM memory should be erased after the replacement. Neglecting this initialization may cause excessive shift shock.
^ Be sure to read Precautions for Electrical Circuit Service before inspection and observe what is written there.
^ TCM and/or ECM replacement:
When substituting a known-good TCM and/or ECM, check for the following conditions. Neglecting this check may result in damage to a good TCM and/or ECM.
- 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.
^ Communication of ECUs, ECM, TCM, and BCM, is established by Computer Area Network (CAN). Therefore, handle CAN communication line with care.