Suzuki Engine 2002 GRAND VITARA SQ625, Service Manual

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ENGINE GENERAL INFORMATION AND DIAGNOSIS (H25 ENGINE) 6-1-13
Data Link Connector (DLC)
DLC (1) in compliance with SAE J1962 in its installation position,
the shape of connector and pin assignment.
K line of ISO 9141 (4) is used for SUZUKI scan tool to communi-
cation with ECM (PCM), Airbag SDM and ABS control module.
SUZUKI serial data line (3) is used for SUZUKI scan tool to com-
municate with an electronic control units (Immobilizer control
module).
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.
– MAP sensor and TP sensor are in good condition and none of power circuits of these sensors is shorted
to ground.
2. B+
5. Body ground
6. ECM (PCM) ground