Precautions

Precautions in Diagnosing Trouble

- Don't disconnect 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) Data 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 and BCM turns on MIL. Therefore, check ECM, TCM and BCM 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 DTCs are stored, proceed to the DTC flow which was detected earliest in the order and follow the instruction in that flow.
If no instructions are given, troubleshoot DTCs 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.
- 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.
- MAF sensor, MAP sensor, TP sensor and EVAP leak check pressure sensor (built-in EVAP leak check module) 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.
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:H27 Engine.
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 ECUs (ECM, TCM, and BCM) is established by CAN (Computer Area Network). Therefore, handle CAN communication line with care referring to Precaution for CAN Communication System.