Precaution In Diagnosing Trouble For Engine - Suzuki Wagon R Plus RB310 Service Manual

6-2-10 ENGINE GENERAL INFORMATION AND DIAGNOSIS (M13 ENGINE)

Precaution in Diagnosing Trouble for Engine

• Don't disconnect couplers from ECM, battery cable from bat-
tery, 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 under-
standing as to what functions are available and how to use it.
It is in 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 ECM for DTC, keep in mind that DTC is dis-
played 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 table of the DTC which has detected ear-
liest in the order and follow the instruction in that table.
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/
P0302/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" in
Section 0A before inspection and observe what is written
there.
• ECM Replacement
When substituting a known-good ECM, check for the follow-
ing 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 ECUs, ECM and TCM, is established by
CAN (Computer Area Network). Therefore, handle CAN
communication line with care referring to "Precaution"
described in Section 0A.