2010 Cadillac CTS Sedan AWD V6-3.6L Page 1025
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:
Conditions for Running the DTC
Condition 1
* Before the ECM can report DTC P0116 failed, DTC P0101 must run and pass.
* DTC P0112, P0113, P0117, P0118, P0119, or P2610 is not set.
* The engine run time of the previous ignition cycle was greater than 10 minutes.
* The calculated engine cool down of the previous test was greater than 50掳C (120掳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 greater than 6,000 grams.
* The DTC runs once an ignition cycle when the above conditions are met for greater than 35 seconds.
Condition 2
* Before the ECM can report DTC P0116 failed, DTC P0101 must run and pass.
* DTCs P0112, P0113, P0117, P0118, and P0119 are not set.
* The ECT at the previous engine shut down is greater than 82掳C (180掳F).
* The block heater is not detected.
* The ignition was OFF for greater than 330 minutes after the previous engine shut down.
* DTC runs once an ignition cycle when the above conditions are met.
Conditions for Setting the DTC
* The ECM determines the difference between the ECT and IAT at ignition ON is not within 14掳C (25掳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 14掳C (25掳F) of the calibrated range.
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 (See: Powertrain
Management/Computers and Control Systems/Specifications) and Temperature Versus Resistance - Intake Air Temperature Sensor (See:
Powertrain Management/Computers and Control Systems/Specifications).
* If the vehicle has sat overnight, the IAT sensor and the ECT sensor values should display within 3掳C (5掳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.
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