Circuit Description
The engine coolant temperature (ECT) sensor is a thermistor mounted in the engine coolant stream. The PCM applies a voltage (about 5.0 volts) through a pull up resistor to the ECT signal circuit. When the engine coolant is cold, the sensor (thermistor) resistance is high, therefore the PCM will measure a high signal voltage. As the engine coolant warms, the sensor resistance becomes less, and the ECT signal voltage measured at the PCM drops. With a fully warmed up engine, the ECT signal voltage should measure about 1.5 to 2.0 volts. If the PCM detects an ECT signal that is intermittently below the range of the ECT sensor, DTC P1114 will set.
Conditions for Running the DTC
The engine has been running longer than 15 seconds.
Conditions for Setting the DTC
The ECT sensor intermittently indicates a coolant temperature less than 114°C (237°F).
Action Taken When the DTC Sets
The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.
Conditions for Clearing the MIL/DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The history DTC clears after 40 malfunction free warm-up cycles. |
| • | The PCM receives a clear code command from the scan tool. |
Diagnostic Aids
Check for the following conditions:
| • | Poor connection at the PCM. |
| Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. |
| • | Damaged harness. |
| Inspect the wiring harness for damage. |
| • | If the harness appears to be OK, observe the ECT display on the scan tool while moving connectors and wiring harnesses related to the ECT sensor. A change in the ECT display will indicate the location of the malfunction. |
| • | Skewed or mis-scaled ECT Sensor. |
| Refer to Temperature Versus Resistance table. |
Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
2 | Select Diagnostic Trouble Codes (DTCs) and note if any other DTCs set. Is DTC P0117 also set? | -- | Go to DTC P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage | |
3 |
Was a problem found? | -- | Go to Diagnostic Aids | |
4 |
Does the scan tool indicate DTC P1114 failed? | -- | System OK |
