Suzuki XL7 2007 Service Manual page 178

1A-73 Engine General Information and Diagnosis:
Circuit Description
The engine coolant temperature (ECT) sensor is a
variable resistor that measures the temperature of the
engine coolant. The engine control module (ECM)
supplies 5 volts to the ECT signal circuit and supplies a
ground to the low reference circuit. The ECM monitors
the mutual performance of the ECT and the intake air
temperature (IAT) signals. The ECM monitors the warm
up and cool down behavior of the sensors, after a
vehicle driven at operating temperature is shut down. If
the ECM detects that the ECT is not with in a
predetermined range of IAT after a long soak, or the ECT
and IAT are not within a range of each other, as
compared to a previous cold start, this DTC sets.
The following table illustrates the difference between
temperature, resistance, and voltage:
ECT ECT Resistance
Cold
Warm
Conditions for Running the DTC
Condition 1
• Before the ECM can report DTC P0116 failed, DTC
P0101 must run and pass.
• DTCs P0012, P0013, P0117, P0118, P0119, and
P2610 are not set.
• The engine run time of the previous ignition cycle was
more than 10 minutes.
• The calculated engine cool down of the previous test
was more than 50°C (120°F).
• The ignition was OFF for greater than 330 minutes
after the previous engine shut down.
• The accumulated air mass of the previous ignition
cycle was more than 6,000 grams
• DTC P0116 runs once an ignition cycle when the
above conditions are met.
Condition 2
• Before the ECM can report DTC P0116 failed, DTC
P0101 must run and pass.
• DTCs P0012, P0013, P0117, P0118, and P0119 are
not set.
• The ECT at the previous engine shut down is more
than 75°C (167°F).
• The block heater is not detected.
• The ignition was OFF for greater than 330 minutes
after the previous engine shut down.
• DTC P0116 runs once an ignition cycle when the
above conditions are met.
ECT Signal
Voltage
High High
Low Low
Conditions for Setting the DTC
• The ECM determines the difference between the ECT
and IAT at ignition ON is not within 15°C (26°F) of the
difference recorded during a previous ignition cycle,
when the enable conditions were met.
OR
• The ECM determines the IAT at ignition ON is within a
calibrated range of the ECT and IAT recorded during a
previous ignition cycle, but the ECT is not within 15°C
(26°F) of the calibrated range.
• The condition exists for more than 4 seconds or
cumulative of 50 seconds.
Action Taken When the DTC Sets
DTC P0116 is a Type A/B DTC.
Conditions for Clearing the MIL/DTC
DTC P0116 is a Type A/B DTC.
Diagnostic Aids
• Test the ECT and the IAT sensor at various
temperature levels in order to evaluate the possibility
of a skewed sensor. A skewed sensor can result in a
DTC or a driveability condition. Refer to "Temperature
Versus Resistance - Engine Coolant Temperature
Sensor" and "Temperature Versus Resistance - Intake
Air Temperature Sensor".
• If the vehicle has sat overnight, the IAT sensor and
the ECT sensor values should display within 3°C
(5°F).
• After starting a cold engine, the ECT sensor
temperature should rise steadily, then stabilize after
the thermostat opens.
• High resistance in the circuits of either the ECT or IAT
sensor could set a DTC.
• A short to ground or voltage through a conductive
material or fluid could set this DTC. Inspect the ECT
sensor for evidence of coolant leaking into the
connector body.