B1311

Diagnostic Trouble Code Chart:

Wiring Schematic:

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
Turn the ignition to the ON position.

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

ACTION TAKEN WHEN THE DTC SETS
^ Dashes are displayed on the PC 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 INTERMITTENTS
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. The Scan Tool displays the ambient temperature. Disconnecting the sensor determines whether the wiring or the sensor is the cause.