Precautions In Diagnosing Trouble

Precautions in Diagnosing Trouble

^ Don't disconnect ECM couplers from ECM, battery cable from 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-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 (For details of on-board diagnostic system for A/T model, 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-II generic scan tool displays DTC detected by each of ECM and TCM simultaneously.

^ Priorities for diagnosing troubles
If two or more diagnostic trouble codes (DTCs) are stored, proceed to the flow of the DTC which has detected earliest in the order and follow the instruction in that table. If no instructions are given, DTCs according to the following priorities.
a. Diagnostic trouble codes (DTCs) other than DTC P0171 / P0172 (Fuel system too lean/too rich) and DTC P0300 / P0301 / P0302 / P0303 / P0304 (Misfire detected)
b. DTC P0171 / P0172 (Fuel system too lean/too rich)
c. DTC P0300 / P0301 / P0302 / P0303 / P0304 (Misfire detected)

^ Be sure to read Precaution for CAN Communication System 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 known good ECM.
^ Resistance value of all relays, actuators is as specified respectively.
^ APP sensor, TP sensor, A/C refrigerant pressure sensor and EVAP leak check pressure sensor are in good condition and none of power circuits of these sensors is shorted to ground.

^ VIN (vehicle identification number) data registration after ECM replacement (EVAP leak check model)
When ECM is replaced with new one (VIN data is still not registered) or with used one (VIN data of other vehicle has been registered previously), make sure that re-register VIN data correctly by performing VIN Registration (EVAP Leak Check Model). Otherwise, MIL remains on even if the engine started or it causes the inconsistency between registered VIN data in ECM and actual VIN.

^ Communication of ECM, BCM, combination meter, keyless start control module, ABS / ESP(R) control module, 4WD control module, steering angle sensor (ESP(R) model) and TCM, is established by CAN (Controller Area Network). (For more detail of CAN communication for ECM, refer to CAN Communication System Description). Therefore, handle CAN communication line with care referring to Precaution for CAN Communication System.
^ Immobilizer transponder code registration after replacing ECM (Immobilizer model) When ECM is replaced with new one or with another one, make sure to register immobilizer transponder code to ECM correctly according to Procedure after ECM Replacement.