Diagnostic Instructions
| • | 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. |
DTC Descriptors
DTC P0115 03: Engine Coolant Temperature (ECT) Sensor Circuit Voltage Below ThresholdDTC P0115 07: Engine Coolant Temperature (ECT) Sensor Circuit Voltage Above Threshold
DTC P0116: Engine Coolant Temperature (ECT) Sensor Performance
DTC P0117: Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage
DTC P0118: Engine Coolant Temperature (ECT) Sensor Circuit High Voltage
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: Engine operating in Closed Loop. Parameter Normal Range: -39 to 142°C (-38 to 288°F) Varies with coolant temperature. | |||
ECT Sensor Signal | 149°C (300°F) | -40°C (-40°F) | -40°C (-40°F)¹ |
Low Reference | -- | -40°C (-40°F) | -40°C (-40°F)¹ |
¹ Internal ECM or ECT sensor damage may occur if the circuit is shorted to B+ | |||
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 following table illustrates the difference between temperature, resistance, and voltage:
ECT | ECT Resistance | ECT Signal Voltage |
|---|---|---|
Cold | High | High |
Warm | Low | Low |
Conditions for Running the DTC
P0115 03, P0115 07, P0117, P0118
The ignition is ON.
P0116
| • | DTCs P0115, P0117, or P0118 are not set. |
| • | The engine speed is greater than 1,000 RPM. |
Conditions for Setting the DTC
P0115 03, P0117
The ECM detects the ECT voltage is less than 117 mV for greater than 1 second.
P0115 08, P0118
The ECM detects the ECT voltage is greater than 4.96 V for greater than 1 second.
P0116
The ECM detects the ECT sensor does not reach the minimum threshold within a calibrated time.
Action Taken When the DTC Sets
DTCs P0115, P0116, P0117, and P0118 are Type B DTCs.
Conditions for Clearing the DTC
DTCs P0115, P0116, P0117, and P0118 are Type B DTCs.
Diagnostic Aids
| • | Test the ECT 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 . |
| • | If the engine 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. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
- Engine idling for 1 minute. Observe the DTC information with a scan tool. DTCs P0115, P0116, P0117 and P0118 should not set.
- Operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.
Circuit/System Testing
- Ignition OFF, and the MAIN fuse removed, disconnect the ECT sensor.
- Test for less than 5 ohms between the low reference circuit terminal 2 and ground.
- Install the MAIN fuse. Ignition ON, verify that the ECT sensor parameter is at -40°C (-40°F).
- Ignition ON, connect a 3A fused jumper wire between the signal circuit terminal 2 and ground. Verify the ECT sensor parameter is greater than 142°C (288°F).
- If all circuits/connections test normal, test or replace the ECT sensor.
| ⇒ | If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the signal circuit for a short to ground. If the circuit/connections test normal, replace the ECM. |
Notice: Do NOT use the low reference circuit in the component harness connector for this test. Damage to the control module may occur due to excessive current draw.
Important: If the fuse in the jumper wire opens, the signal circuit is shorted to a voltage and the sensor may be damaged.
| ⇒ | If less than the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM. |
Component Testing
Measure and record the resistance between the signal circuit terminal 2 and the low reference circuit terminal 1 at various ambient temperatures. Compare those measurements to the Temperature Versus Resistance table and verify that the resistance is within 5 percent of the specification.
| ⇒ | If not within the specified range, replace the ECT sensor |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for engine control module replacement, setup, and programming |
