Pinpoint Test C: DTC B1B71:11 Or B1B71:13
Climate Control System
Pinpoint Test C: DTC B1B71:11 or B1B71:13
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
The evaporator discharge air temperature sensor receives a ground from the Instrument Panel Cluster (IPC). The sensor varies its resistance with the temperature. As the temperature rises, the resistance falls. As the temperature falls, the resistance rises. The IPC measures this resistance on the feedback circuit to determine the temperature at the sensor. The sensor value is sent from the IPC to the PCM through the High Speed Controller Area Network (HS-CAN).
The evaporator discharge air temperature sensor is used for A/C compressor cycling. An accurate evaporator discharge air temperature is critical to prevent evaporator icing. The PCM uses the temperature measurement to turn off the A/C compressor before the evaporator temperature is cold enough to freeze the condensation. This prevents ice blockage of airflow over the evaporator core.
- DTC B1B71:11 (Evaporator Discharge Air Temperature Sensor: Circuit Short to Ground) - The module senses lower than expected voltage on the sensor feedback circuit, indicating a short to ground.
- DTC B1B71:13 (Evaporator Discharge Air Temperature Sensor: Circuit Open) - The module senses greater than expected voltage on the sensor feedback circuit, indicating an open circuit or sensor.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Evaporator discharge air temperature sensor
- IPC
PINPOINT TEST C: DTC B1B71:11 OR B1B71:13
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C1 CHECK THE SENSOR RESISTANCE
- Ignition OFF.
- Disconnect: Evaporator Discharge Air Temperature Sensor C296.
- Allow enough time for the evaporator to stabilize to the ambient temperature.
- Measure the resistance between evaporator discharge air temperature sensor C296 terminals and compare to the table below.
- Is the resistance within the specified values for the temperatures?
Yes
GO to C2.
No
INSTALL a new evaporator discharge air temperature sensor. REFER to Climate Control Service and Repair. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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C2 CHECK THE IPC SENSOR OUTPUT VOLTAGE
- Ignition ON.
- Select PANEL and press the A/C button (indicator on) on the HVAC controls.
- Measure the voltage between evaporator discharge air temperature sensor C296-1, circuit VH406 (VT/BN), harness side and C296-3, circuit RH119 (YE/VT), harness side.
- Is the voltage between 4.7 and 5.1 volts?
Yes
INSTALL a new evaporator discharge air temperature sensor. REFER to Climate Control Service and Repair. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. If the DTC returns, GO to C7.
No
If diagnosing DTC B1B71:13, GO to C3.
If diagnosing DTC B1B71:11, GO to C5.
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C3 CHECK THE EVAPORATOR TEMPERATURE SENSOR FEEDBACK CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Instrument Panel Cluster (IPC) C220.
- Measure the resistance between IPC C220-26, circuit VH406 (VT/BN), harness side and evaporator discharge air temperature sensor C296-1, circuit VH406 (VT/BN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to C4.
No
REPAIR circuit VH406 (VT/BN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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C4 CHECK THE SIGNAL RETURN CIRCUIT FOR AN OPEN
- Measure the resistance between IPC C220-24, circuit RH119 (YE/VT), harness side and evaporator discharge air temperature sensor C296-3, circuit RH119 (YE/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to C7.
No
REPAIR circuit RH119 (YE/VT) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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C5 CHECK THE EVAPORATOR TEMPERATURE SENSOR FEEDBACK CIRCUIT FOR A SHORT TO THE SIGNAL RETURN CIRCUIT
- Ignition OFF.
- Disconnect: IPC C220.
- Measure the resistance between evaporator discharge air temperature sensor C296-1, circuit VH406 (VT/BN), harness side and C296-3, circuit RH119 (YE/VT), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to C6.
No
REPAIR circuits VH406 (VT/BN) and RH119 (YE/VT) for a short together. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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C6 CHECK THE EVAPORATOR TEMPERATURE SENSOR FEEDBACK CIRCUIT FOR A SHORT TO GROUND
- Measure the resistance between IPC C220-26, circuit VH406 (VT/BN), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to C7.
No
REPAIR circuit VH406 (VT/BN) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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C7 CHECK THE IPC CONNECTION
- Disconnect all the IPC connectors.
- Inspect the IPC connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat all the IPC connectors.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new IPC. REFER to Instrumentation, Message Center, and Warning Chimes Service and Repair. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. TEST the system for normal operation.
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