Precaution In Diagnosing Trouble - Suzuki GRAND VITARA XL-7 Owner's Manual

6-1-10 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)

Precaution in Diagnosing Trouble

• Don't disconnect couplers from ECM (PCM), battery cable from battery, ECM (PCM) ground wire harness
from engine or main fuse before confirming diagnostic information (DTC, freeze frame data, etc.) stored in
ECM (PCM) memory. Such disconnection will erase memorized information in ECM (PCM) memory.
• Diagnostic information stored in ECM (PCM) memory can be cleared as well as checked by using SUZUKI
scan tool or 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.
• Priorities for diagnosing troubles (Vehicle without monitor connector)
If two or more diagnostic trouble codes (DTCs) are stored, proceed to the flow table of the DTC which was
detected earliest 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/P0174/P0175 (Fuel system too lean/too
rich), DTC P0300/P0301/P0302/P0303/P0304/P0305/P0306 (Misfire detected) and DTC P0400 (EGR
flow malfunction)
– DTC P0171/P0172/P0174/P0175 (Fuel system too lean/too rich) and DTC P0400 (EGR flow malfunction)
– DTC P0300/P0301/P0302/P0303/P0304/P0305/P0306 (Misfire detected)
• Be sure to read "PRECAUTIONS FOR ELECTRICAL CIRCUIT SERVICE" in Section 0A before inspection
and observe what is written there.
• ECM (PCM) Replacement
When substituting a known-good ECM (PCM), check for following conditions. Neglecting this check may
cause damage to a known-good ECM (PCM).
– Resistance value of all relays, actuators is as specified respectively.
– MAF sensor, MAP sensor and TP sensor are in good condition and none of power circuits of these sen-
sors is shorted to ground.
DATA LINK CONNECTOR (DLC)
DLC (1) is in compliance with SAEJ1962 in its installation posi-
tion, the shape of connector and pin assignment.
K line of ISO 9141 is used for SUZUKI scan tool to communicate
with ECM (PCM), ABS control module and air bag SDM. SUZUKI
serial data line is used for SUZUKI scan tool to communicate with
Immobilizer control module.
2. B+
3. SUZUKI Serial data line
4. K line of ISO 9141
5. Body ground
6. ECM ground