GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2001 🢒 Seville - RHD 🢒 DTC 🢒 DTC P1111

Circuit Description

The intake air temperature (IAT) sensor is a thermistor, a variable resistor, that measures the temperature of the air entering the engine. The powertrain control module (PCM) supplies 5 volts to the IAT signal circuit through a pull-up resistor. When the intake air is cold, the PCM detects a high voltage on the IAT signal circuit. As the intake air warms, the PCM detects a lower voltage on the IAT signal circuit. If the PCM detects an intermittently high IAT signal voltage, indicating a low temperature, this diagnostic trouble code (DTC) will set.

Conditions for Running the DTC
    • DTCs P0101, P0102, P0103, P0117, P0118, P0125, P0502, P0503, P1114, or P1115 are not set.
    • The engine has been running for at least 5 seconds.
    • The engine coolant temperature (ECT) is more than 60°C (140°F).
    • The mass air flow (MAF) is less than 12 g/s.
    • The vehicle speed is less than 80 km/h (48 mph).

Conditions for Setting the DTC
    • The IAT sensor signal voltage is more than 4.8 volts at -24°C (-12°F).
    • The condition exists 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 IAT sensor signal circuit for the following intermittent conditions:
    2. • A short to voltage
    • An open signal circuit
    • A poor connection at the PCM or the IAT 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 and Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

Go to Step 5

Go to Step 4

4
  1. Test the IAT sensor low reference circuit for the following intermittent conditions:
    2. • An open circuit
    • A poor connection at the PCM or the IAT 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 and Repairing Connector Terminals 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.

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