B0176

Diagnostic Trouble Code Chart:

Wiring Schematics:

CIRCUIT DESCRIPTION
The upper discharge air temperature sensor is a thermistor used in order to control the signal voltage in the Electronic Climate Control (ECC) module. The ECC module supplies a reference voltage (about 5 volts) on CKT 404 to the sensor. When the upper duct air temperature is cold, the thermistor resistance is high. Therefore, the ECC module will receive a high voltage input. If the upper duct air temperature is hot, the thermistor resistance is low. Therefore, the ECC module will receive a low signal voltage input. The upper discharge air temperature sensor is used in order to enhance the temperature control. Refer to Sensor Resistance Table. Sensor Resistance Table - HVAC System - Automatic

CONDITIONS FOR SETTING THE DTC
When the ignition is ON, the ECC module will detect DTC B0176 any time that CKT 404 is at or near 5 volts or higher.

ACTION TAKEN WHEN THE DTC SETS
The ECC module will use a default value of 10 A/D counts until the fault is cleared.

CONDITIONS FOR CLEARING THE MIL/DTC
This fault will clear as soon as the fault goes away or has been repaired. The system will then return to normal operation. History DTCs may only be cleared by removing and restoring B+ or by using the scan tool.

DIAGNOSTIC AIDS
^ The ECC module may set class 2 lost communication DTCs when the Body Control Module (BCM) or the Vehicle Control Module (VCM) is being reprogrammed. After reprogramming, inspect for DTCs in the ECC module. Clear any history U DTCs, then resume diagnostics.
^ Visually inspect the sensor connector and harness for corrosion and damage. The resistance value of the sensor must be 334-100,865 ohm. Refer to Sensor Resistance Table. If resistance is not within specifications, replace the sensor.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
2. This step measures the resistance of the upper discharge air temperature sensor.
3. This step inspects for B+ on CKT 404.
4. This step determines if the short to B+ is in CKT 404 or in the ECC module.
6. This step inspects for an open in CKT 552.
7. This step replaces a defective upper discharge air temperature sensor.
8. This step repairs an open in CKT 552.
9. This step inspects for intermittents and tests for a malfunctioning ECC module.
10. This step replaces a defective ECC module.
11. This step inspects for 5 volts on CKT 404.
12. This step determines if the open is in CKT 404 or in the ECC module.