Pinpoint Test H: DTCs B1B71:11 and 15
Climate Control System
Pinpoint Tests
Pinpoint Test H: DTCs B1B71:11 and 15
Refer to Wiring Diagram Set 55 (Escape/Mariner, Escape Hybrid/Mariner Hybrid), Automatic Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, the evaporator discharge air temperature sensor receives a ground from the HVAC module. The sensor varies its resistance with the temperature. As the temperature rises, the resistance falls. As the temperature falls the resistance rises. The HVAC module measures this resistance to determine the temperature at the sensor.
- 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
PINPOINT TEST H: DTCs B1B71:11 AND 15
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H1 CHECK THE SENSOR RESISTANCE
- Ignition OFF.
- Disconnect: Evaporator Discharge Air Temperature Sensor C296.
- Allow enough time for the evaporator to stabilize to the outside 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 H2.
No
INSTALL a new evaporator discharge air temperature sensor. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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H2 CHECK THE HVAC OUTPUT VOLTAGE
- Ignition ON.
- Press the power button.
- Measure the voltage between evaporator discharge air temperature sensor C296-1, circuit VH406 (VT/BN), harness side and C296-2, circuit RH111 (GY/BU), harness side.
- Is the voltage between 4.7 and 5.1 volts?
Yes
INSTALL a new evaporator discharge air temperature sensor. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation. If code returns, GO to H7.
No
For DTC B1B71:15, GO to H3.
For DTC B1B71:11, GO to H5.
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H3 CHECK CIRCUIT VH406 (VT/BN) FOR AN OPEN
- Ignition OFF.
- Disconnect: HVAC Module C2356A.
- Measure the resistance between HVAC module C2356A-6, 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 H4.
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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H4 CHECK CIRCUIT RH111 (GY/BU) FOR AN OPEN
- Measure the resistance between HVAC module C2356A-10, circuit RH111 (GY/BU), harness side and evaporator discharge air temperature sensor C296-2, circuit RH111 (GY/BU), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to H7.
No
REPAIR circuit RH111 (GY/BU) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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H5 CHECK CIRCUIT VH406 (VT/BN) FOR A SHORT TO CIRCUIT RH111 (GY/BU)
- Ignition OFF.
- Disconnect: HVAC Module C2356A.
- Measure the resistance between evaporator discharge air temperature sensor C296-1, circuit VH406 (VT/BN), harness side and C296-2, circuit RH111 (GY/BU), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to H6.
No
REPAIR circuit VH406 (VT/BN) for a short to circuit RH111 (GY/BU). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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H6 CHECK CIRCUIT VH406 (VT/BN) FOR A SHORT TO GROUND
- Measure the resistance between HVAC module C2356A-6, circuit VH406 (VT/BN), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to H7.
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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H7 CHECK THE HVAC MODULE CONNECTION
- Inspect the HVAC module connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.
- Connect and correctly seat all the HVAC module connectors.
- Clear the DTCs.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new HVAC module. REFER to Climate Control 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.
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