DTC P1115 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent High Voltage. Cadillac Seville 2000

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2000 🢒 Seville 🢒 Engine 🢒 Engine Controls - 4.6L 🢒 DTC P1115 Engine Coolant Temperature (ECT) Sensor Circuit Intermittent High Voltage

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OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The engine coolant temperature (ECT) sensor is a thermistor, or variable resistor, that measures the temperature of the engine coolant. The PCM supplies 5 volts to the ECT signal circuit through a pull-up resistor. When the engine coolant temperature is cold, the sensor resistance is high. When the engine coolant temperature 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 intermittently high ECT signal voltage (a low temperature indication), DTC P1115 will set.

Conditions for Running the DTC

•	IAT sensor DTCs are not set.

•	The engine has been running for 60 seconds.

•	The intake air temperature is above -7°C (19°F).

Conditions for Setting the DTC

•	The ECT sensor signal voltage is more than 4.9 volts. This would be approximately -21°C (-7°F).

•	The conditions exists for less than 1 second.

Action Taken When the DTC Sets

•	The PCM will illuminate the malfunction indicator lamp (MIL) the first time the malfunction is detected.

•	The PCM will store the conditions present when the DTC set as Freeze Frame and Fail Records data.

Conditions for Clearing the MIL/DTC

•	The PCM will turn the MIL OFF during the third consecutive trip in which the diagnostic runs and passes.

•	The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

•	The DTC can be cleared by using the scan tool Clear DTC Information function.

Diagnostic Aids

If the condition is intermittent, refer to Intermittent Conditions .

Step

Action

Values

Yes

Did you perform the Powertrain On Board Diagnostic (OBD) System Check?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Are any other DTCs also set?

Go to Diagnostic Trouble Code (DTC) List/Type

Go to Step 3

Test the ECT sensor signal circuit for the following intermittent conditions:

•	Short to voltage

•	Open signal circuit

•	Poor connections at the PCM or the ECT sensor, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems

Did you find and correct the condition?

Go to Step 5

Go to Step 4

Test the ECT sensor ground circuit for the following intermittent conditions:

•	An open circuit

•	Poor connections at the PCM or the ECT sensor, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

If a condition is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 5

Go to Diagnostic Aids

Review and record the scan tool Fail Records data.
Clear the DTCs.
Operate the vehicle within the parameters listed in the Conditions for Running the DTC.
With the scan tool, monitor the Specified DTC Information for DTC P1115.

Does the scan tool indicate that DTC P1115 passed?

System OK

Go to Step 2