GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2002 🢒 DeVille 🢒 Engine 🢒 Engine Controls - 4.6L 🢒 DTC P1115

Circuit Description

The engine coolant temperature (ECT) sensor is a thermistor, or variable resistor, that measures the temperature of the engine coolant. The powertrain control module (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, this DTC will set.

Conditions for Running the DTC
    • DTCs P0112, P0113, P1111, or P1112 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 temperature is less than -38°C (-36°F) for more than 10 seconds.
    • The conditions exist for less than 1 second.

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.
    • Clear the DTC with a scan tool.

Diagnostic Aids

If the condition is intermittent, refer to Intermittent Conditions .

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Are any other DTCs also set?

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3
  1. Test the ECT sensor signal circuit for the following intermittent conditions:
    2. • A short to voltage
    • An open signal circuit
    • Poor connections at the PCM or at the ECT sensor--Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. 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

4
  1. Test the ECT sensor ground circuit for the following intermittent conditions:
    2. • An open circuit
    • Poor connections at the PCM or the ECT sensor--Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. 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 Intermittent Conditions

5

  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text.

Does the DTC run and pass?

Go to Step 6

Go to Step 2

6

With a scan tool observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK