Normal Operation
WARNING: This page is about a different car, the 2011 Mercury Milan, 2011 Lincoln MKZ, and 2011 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
Under normal operation, the evaporator discharge air temperature sensor receives a ground from the HVAC module through circuit RH111 (GY/BU). A 5- volt reference voltage is supplied to the evaporator discharge air temperature sensor from the HVAC module through circuit VH406 (VT/BN).
- DTC B1B71:11 (Evaporator Temperature Sensor: Circuit Short to Ground) - The module senses excessive voltage drop on the sensor reference voltage circuit, indicating a short directly to ground.
- DTC B1B71:15 (Evaporator Temperature Sensor: Circuit Short to Battery or Open) - The module senses no voltage drop on the sensor reference voltage circuit, indicating a short directly to voltage or an open circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Evaporator discharge air temperature sensor
- HVAC module