DTC 06

CIRCUIT DESCRIPTION

The inside air temperature sensor (3) is a thermistor that provides a signal voltage to the control assembly microprocessor (15).

The microprocessor (15) supplies a reference voltage (about 5 volts) on CKT 734 to the inside air temperature sensor (3). When the inside air temperature is cold. the thermistor resistance is high; therefore, the microprocessor (15) will receive a high signal voltage input. If the inside air temperature is high, the thermistor resistance is low; therefore, the microprocessor (15) will receive a low signal voltage input.

TEST DESCRIPTION

The following numbers refer to circled numbers on the diagnostic chart.

1. This test will determine if the microprocessor (15) has defaulted to a default value of 128 which represents 10°C (75°F) and Code 06 has set. Code 06 will set if:

^ a low resistance (short) is present for more than 1.6 seconds, or the microprocessor (15) detects a large change in resistance in a short period of time, based on the microprocessor 5 error program.

2. This test will determine if the inside air temperature sensor (3) is within its parameter. The resistance varies with temperature so the Diagnostic Aid Correction Chart must be used if inside temperature is not 16°C (59°F).

3. This test will determine if a short to power or ground exists in the 5-volt reference voltage wire.

4. This test will determine if the microprocessor (15) is functioning properly. The disconnected harness should set a sensor open Code 05.

DIAGNOSTIC AIDS

A "scan" tool can be used if a 06 Code is not set. Check resistance (or counts) of the inside air temperature sensor (3), hot and cold. Compare the reading with the Diagnostic Aid Correction Chart. The inside air temperature sensor (3) is to be replaced if out of range, hot or cold.

If the sensor is within limits, carefully check harness and connections for short to power in circuits 734 and 198.