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For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2000 🢒 Eldorado 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 DTC B1311 Outside Air Temp Sensor Short Circuit

Object Number: 594846 Size: MF
HVAC Components
Temperature Sensors
Handling ESD Sensitive Parts Notice
ANTENNA, RSS, HTD MIR, and HTD BACKLT Fuses
ANTENNA, RSS, HTD MIR, and HTD BACKLT Fuses
Temperature Sensors

Circuit Description

The ambient air temperature sensor is a thermistor which controls the signal voltage to the heater and A/C programmer. The heater and A/C programmer supplies voltage on CKT 735. When the sensor is cold, the following conditions exist:

    • The resistance is high.
    • The heater and A/C programmer reads a high signal voltage at pin C8.

When the sensor warms, the following actions occur:

    • The resistance is reduced.
    • The signal voltage is pulled low through CKT 407.

The signal voltage varies from 5 V (open circuit) to 0 V (short circuit).

Conditions for Running the DTC
    • Ignition in the ON position
    • Circuit shorted

Diagnostic Aids

If the ambient temperature drops below -38°C (-37°F), ignore this DTC.

Action Taken When the DTC Sets
    • Dashes are displayed on the IPC or CCP (with the analog IPC) temperature display.
    • A default value of 15°C (60°F) is used in order to allow the operation of the A/C system.

Notes on Intermittence

If an intermittent DTC B1311 is set, connect the Scan Tool and select the following options:

    • Data list
    • Open/shorts data
    • Observe the reading

Manipulate the wiring while observing the Scan Tool . If a failure is induced, the reading will jump. Inspect for a the following conditions:

    • A poor terminal contact
    • An obstructed or defective sensor

Test Description

  1. Perform the Diagnostic System Check before continuing with the diagnosis of this DTC.

    2.

  2. The Scan Tool displays the ambient temperature. Disconnecting the sensor determines whether the wiring or the sensor is the cause.

Step

Action

Value(s)

Yes

No

1

Did you perform the diagnostic system check?

--

Go to Step 2

Go to Diagnostic System Check

2

  1. Turn the ignition to the ON position.
  2. Connect the Scan Tool .
  3. Disconnect the sensor.

Did the DTC change from B1311 to B1310?

--

Go to Step 4

Go to Step 3

3
  1. Disconnect the heater and A/C programmer and the sensor.
  2. Connect the test lamp between C8 and B+.

Did the test lamp light?

--

Go to Step 6

Go to Step 5

4
  1. Replace the sensor. Refer to Ambient Temperature Sensor Replacement
  2. Using the Scan Tool clear the code.

Is the repair complete?

--

Go to Diagnostic System Check

--

5
  1. Inspect the terminal contact.
  2. If OK, replace the heater and A/C programmer. Refer to Programmer Replacement
  3. Using the scan tool clear the code.

Is the repair complete?

--

Go to Diagnostic System Check

--

6
  1. Repair the short to ground in CKT 735. Refer to Wiring Repairs in Wiring Systems.
  2. Using the Scan Tool clear the code.

Is the repair complete?

--

Go to Diagnostic System Check

--