Suzuki XL7 2007 Service Manual page 187

DTC P0125 or P0128
Diagnostic Instructions
• Perform the "Diagnostic System Check - Vehicle
Diagnostic Information: " prior to using this diagnostic
procedure.
• Review "Strategy Based Diagnosis: " for an overview
of the diagnostic approach.
• "Diagnostic Procedure Instructions - Vehicle
Diagnostic Information: " provides an overview of
each diagnostic category.
DTC Descriptors
DTC P0125: Engine Coolant Temperature (ECT)
Insufficient for Closed Loop
DTC P0128: Engine Coolant Temperature (ECT) Below
Thermostat Regulating Temperature
Circuit Description
The engine control module (ECM) monitors the
temperature of the engine coolant for engine control and
as an enabling criteria for some diagnostics. The amount
of air flow into an engine is proportional to the amount of
heat an engine generates. The ECM monitors the
amount of air flow into the engine to calculate engine
coolant temperature (ECT). The ECM uses the
calculated temperature to determine if the engine has
warmed up to the closed loop temperature or to the
thermostat regulating temperature. If the coolant
temperature does not increase normally or does not
reach the closed loop temperature, diagnostics that use
the ECT as enabling criteria, may not run when
expected.
Conditions for Running the DTC
P0125
• DTCs P0112, P0113, P0117, P0118, P0480, P0481,
P0691, P0692, P0693, and P0694 are not set.
• The engine is operating.
P0128
• Before the ECM can report DTC P0128 failed, DTC
P0117 must run and pass.
• DTCs P0100, P0101, P0102, P0103, P0111, P0112,
P0113, P0116, P0117, P0118, P0119, P0722, or
P0723 are not set.
• The engine speed is more than 960 RPM.
• The ECT is less than 71°C (160°F) at start up.
• The calculated ambient air temperature is more than −
11°C (−12°F) and less than 70°C (158°F).
• The vehicle speed is more than 15 km/h (9 mph).
• The air flow coming into the engine has accumulated
to more than 3,000 grams.
• DTC P0128 runs continuously once the above
conditions have been met for approximately 15
minutes.
Engine General Information and Diagnosis:
Conditions for Setting the DTC
P0125
The actual ECT is not within 10°C (18°F) of the
calculated ECT after 2-5 minutes, which depends on the
amount of air flow into the engine after start-up.
P0128
• The ECM detects that the actual coolant temperature
is 10°C (18°F) less than the calculated coolant
temperature.
• The condition exists for more than 4 seconds or for a
cumulative of 50 seconds.
Action Taken When the DTC Sets
DTCs P0125 and P0128 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0125 and P0128 are Type B DTCs.
Diagnostic Aids
An engine that soaks for about 8 hours will help
diagnosis the condition. After the cold soak, operate the
vehicle at highway speeds for 20 minutes while
monitoring the Calculated ECT - Thermostat parameter
with a scan tool. If there is a condition, the calculated
temperature will be 10°C (18°F) more then the actual
engine coolant temperature.
Reference Information
Schematic Reference
"Engine Controls Schematics"
Connector End View Reference
• "Engine Control Module Connector End Views"
• "Engine Controls Connector End Views"
Electrical Information Reference
• "Circuit Testing: "
• "Connector Repairs: "
• "Testing for Intermittent Conditions and Poor
Connections: "
• "Wiring Repairs: "
DTC Type Reference
"Powertrain Diagnostic Trouble Code (DTC) Type
Definitions"
Scan Tool Reference
• "Scan Tool Data List - Engine Controls - 3.6L (LY7)"
• "Scan Tool Data Definitions - Engine Controls - 3.6L
(LY7)"
• "Scan Tool Output Controls - Engine Controls - 3.6L
(LY7)"
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