P1115

CIRCUIT DESCRIPTION
The Engine Coolant Temperature (ECT) sensor is a variable resistor, sometimes called a thermistor, that measures the temperature of the engine coolant. The Powertrain Control Module (PCM) supplies 5 volts to the ECT signal circuit. When the ECT is cold, the sensor resistance is high. When the ECT increases, the sensor resistance lowers. With high sensor resistance, the PCM detects a high voltage on the ECT signal circuit. With lower sensor resistance, the PCM detects a lower voltage on the ECT signal circuit. If the PCM detects an excessively high signal voltage, which is a low temperature indication, this Diagnostic Trouble Code (DTC) will set.

CONDITIONS FOR RUNNING THE DTC
Engine run time is more than 60 seconds.

CONDITIONS FOR SETTING THE DTC
The Powertrain Control Module (PCM) detects an Engine Coolant Temperature (ECT) sensor temperature less than 35°C (-31°F).

The intermittent condition exists for a total of 1 seconds during a 20 second time period.

ACTION TAKEN WHEN THE DTC SETS
^ The control module stores the DTC information into memory when the diagnostic runs and fails.
^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
^ The driver information center, if equipped, may display a message.

CONDITIONS FOR CLEARING THE DTC
^ A current DTC Last Test Failed clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
^ Use a scan tool in order to clear the DTC.

DIAGNOSTIC AIDS
^ An ECT sensor or PCM which is intermittently shorted, open, or skewed is possible yet very unlikely
^ An intermittent open or short to voltage in the ECT sensor signal circuit could result in a DTC P1115. If the high ECT voltage (low temperature) reading is present, additional sensor circuit voltage codes could be set. Refer to any non-intermittent DTCs that are set.
^ Use the Temperature vs. Resistance Value scale in order to test the coolant sensor at various temperature levels in order to evaluate the possibility of a skewed sensor. A skewed sensor could result in poor driveability complaints. Refer to Temperature vs Resistance. Temperature VS Resistance

TEST DESCRIPTION

Steps 1-9:

The number below refers to the step number on the diagnostic table.
5. If there is no driveability complaint associated with the DTC and it does not reset, then the system is OK.