P0117

ECT Sensor Circuit Low Voltage:

ECT Sensor Circuit:

Circuit Description

The Engine Coolant Temperature (ECT) sensor is a thermistor, a sensor whose resistance varies with temperature. The ECT sensor signal is on CKT 410 and sensor ground on CKT 808. As the temperature of the sensor increases, resistance decreases. A high coolant temperature will result in low signal voltage on CKT 410. DTC P0117 sets because the coolant temperature cannot be greater than 147°C (297°F) when the Intake Air Temperature (IAT) sensor is less than 100°C (212°F) or the vehicle has been driving long enough to cool the engine to less than 147°C (297°F).


Conditions for Setting the DTC

Test Conditions

^ DTCs P0112 and P0113 not set.

^ IAT temperature of 100°C (212°F) or less.

OR

^ DTCs P0122 and P0123 not set.

^ Engine running with throttle angle between 5 and 35 degrees for at least 3.5 minutes.

Failure Condition

The ECT sensor reading is 147°C (297°F) or more.


Action Taken When the DTC Sets

^ PCM turns ON the SERVICE EMISSION SYSTEM message.

^ PCM uses the transaxle temperature sensor values in place of the engine coolant temperature sensor for the first 4.25 minutes of engine operation and a value of 90°C (194°F).

^ Transaxle shift adapts are maintained at current levels.

^ The PCM will illuminate the Malfunction Indicator Lamp (MIL) when the diagnostic runs and fails.

^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records.


Conditions for Clearing the MIL/DTC

^ The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.

^ A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.

^ A History DTC will clear after forty consecutive warm-up cycles with no failures of any emission related diagnostic test.

^ PCM battery voltage is interrupted.

^ Using a Scan tool.


Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

2. With the ECT sensor or wiring shorted, ECT display will read 147°C (247°F) or greater.

3. If ECT display reads -29°C (20°F) or less with ECT sensor disconnected, wiring is okay but ECT sensor must be shorted.