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| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Signal Circuit | P0117 00 | P0118 00 | P0118 00* | P0116 00 |
Low Reference | - | P0118 00 | P0118 00* | P0116 00 |
*ECM or sensor damage may occur if the circuit is shorted to B+ | ||||
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: Engine operating in closed loop. Parameter Normal Range: Varies with coolant temperature | |||
Signal | 150°C (302°F) | -40°C (-40°F) | -40°C (-40°F) |
Low Reference | - | -40°C (-40°F) | -40°C (-40°F) |
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 V to the ECT sensor signal circuit and a ground for the low reference circuit.
The purpose of this diagnostic is to determine if the input from the ECT sensor is skewed warmer than normal. The internal clock of the ECM will record the amount of time the engine is OFF. If the required engine OFF time is met at start-up, the ECM will compare the temperature difference between the actual measured ECT and a calibrated ECT model. The information for this model is derived from the previous drive cycle and includes the accumulated mass air flow (MAF), the engine run time, the ambient air temperature and the ECT at the end of the drive cycle.
If the ECM detects that the temperature difference between the measured and modelled ECT is not within an acceptable operating range of each other, then the ECM will continue to run this diagnostic to determine if a block heater was active during the engine OFF time.
| • | DTCs P0112 00, P0113 00, P0117 00, P0118 00, and P2610 00 are not set. |
| • | The ignition has been off for longer than 8 h before the engine is started. |
| • | The engine is running. |
| • | This DTC runs once per ignition cycle when the above conditions are met. |
The ECM does not detect an ECT sensor change of greater than 10.5°C (50.9°F) within a calibrated time.
DTC P0116 00 is a Type B DTC.
DTC P0116 00 is a Type B DTC.
| • | Inspect the ECT sensor terminals for corrosion and for engine coolant leaking through the sensor. Engine coolant that is leaking through the sensor will create a high resistance short to ground. This condition results in less voltage on the ECT sensor signal circuit, which is interpreted by the ECM as a warmer ECT. |
| • | An intake air temperature (IAT) sensor that is biased colder at various ambient temperatures due to greater resistance than is normal will increase the range between these 2 sensors. Measure and record the resistance of the IAT sensor at various ambient temperatures, then compare those measurements to the Temperature vs. Resistance table. Refer to Temperature Versus Resistance . |
| • | Test the ECT sensor at various temperature levels in order to evaluate the possibility of a biased sensor. A sensor that is biased warmer can result in a driveability condition. Refer to Temperature Versus Resistance . |
| • | A slight to moderate resistance in the IAT sensor signal circuit or low reference circuit will increase the range between these two sensors. This condition results in a greater voltage on the IAT sensor signal circuit, which is interpreted by the ECM as a colder IAT. |
| • | If the condition is intermittent, allowing the vehicle to sit for longer than 8 h with the ignition off may help isolate the condition. Compare the scan tool Radiator Coolant Temperature Sensor and ECT Sensor temperature sensor values at ignition on. The Radiator Coolant Temperature Sensor and the ECT Sensor parameters should display within 3°C (5°F). |
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
| ⇒ | If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle . |
Note: Depending on ambient temperature, it may take up to 4 min for the temperature to equalise.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module. |
| ⇒ | If greater than the specified range, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module. |
| ⇒ | If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module. |
Note: A thermometer can be used to test the sensor off the vehicle.
| ⇒ | If not within the specified range, replace the B34A Engine Coolant Temperature Sensor 1. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Engine Coolant Temperature Sensor Replacement : Water Outlet → Thermostat → Radiator |
| • | Control Module References for ECM replacement, setup, and programming |
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