Precautions in Diagnosing Trouble
Don’t disconnect couplers from ECM, battery cable at battery, ECM ground wire harness from engine or main fuse before confirming diagnostic information (DTC, freeze frame data, etc.) stored in ECM memory. Such disconnection will erase memorized information in ECM memory.
Diagnostic information stored in ECM memory can be cleared as well as checked by using SUZUKI scan tool or OBD 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 (For details of on-board diagnostic system for A/T, refer to On-Board Diagnostic System Description ). Therefore, check both ECM and TCM for DTC when MIL lights on.
When checking ECM 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 ECM.
OBD generic scan tool displays DTC detected by each of ECM and TCM simultaneously.
Priorities for diagnosing troubles.
If multiple diagnostic trouble codes (DTCs) are stored, proceed to the flow table of the DTC which has been detected earliest in the order and follow the instruction in that flow.
If no instructions are given, troubleshoot diagnostic trouble codes according to the following priorities.
Diagnostic trouble codes (DTCs) other than DTC P0171/P0172 (Fuel system too lean/too rich), DTC P0300/P0301/P0303/P0304 (Misfire detected) and DTC P0401/P0402 (EGR flow malfunction)
DTC P0171/P0172 (Fuel system too lean/too rich) and DTC P0401/P0402 (EGR flow malfunction)
DTC P0300/P0301/P0302/P0303/P0304 (Misfire detected)
Be sure to read Precautions for Electrical Circuit Service before inspection and observe what is written there.
ECM replacement:
When substituting a known-good ECM, check for the following conditions. Neglecting this check may cause damage to a known-good ECM.
Resistance value of all relays, actuators is as specified respectively.
MAP sensor and TP sensor are in good condition and none of power circuits of these sensors is shorted to ground.
Communication of ECM and TCM, is established by CAN (Controller Area Network). (For detail of CAN communication for ECM referring to CAN Communication System Description:M13A with VVT ). Therefore, handle CAN communication line with care, refer to Precaution for CAN Communication System .
ECM/Immobilizer code registration after replacement ECM When ECM is replaced with new one or with another one, make sure to register ECM/immobilizer code to ECM correctly according to Procedure after ECM Replacement:M13A Model .