Pinpoint Test G: DTC B2826 or DTC B2827
Climate Control System
Pinpoint Tests
Pinpoint Test G: DTC B2826 or DTC B2827
Refer to Wiring Diagram Set 55, 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 - Dual Automatic Temperature Control (DATC) through circuit RH104 (BU/BN). A 5-volt reference voltage is supplied to the evaporator discharge air temperature sensor from the HVAC module - DATC through circuit VH406 (VT/BN).
- DTC B2826 Front Evaporator Temp Sensor Circuit Failure - The module senses no voltage drop on the sensor reference voltage circuit, indicating an open circuit.
- DTC B2827 Front Evaporator Temp Sensor Short to Ground - The module senses excessive voltage drop on the sensor reference voltage circuit, indicating a short directly to ground.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Evaporator discharge air temperature sensor
- HVAC module - DATC
PINPOINT TEST G: DTC B2826 OR DTC B2827
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G1 CHECK THE SENSOR RESISTANCE
- Ignition OFF.
- Disconnect: Evaporator Discharge Air Temperature Sensor C2295.
- Carry out the evaporator discharge air temperature sensor component test. Evaporator Discharge Air Temperature Sensor
- Is the resistance within the specified values for the temperatures?
Yes
GO to G2.
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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G2 CHECK THE HVAC MODULE OUTPUT VOLTAGE
- Ignition ON.
- Press the AUTO button.
- Measure the voltage between evaporator discharge air temperature sensor C2295-2, circuit VH406 (VT/BN), harness side and C2295-1, circuit RH104 (BU/BN), harness side.
- Is the voltage between 4.7 and 5.1 volts?
Yes
INSTALL a new evaporator discharge air temperature sensor. If code returns, GO to G7.
No
If diagnosing DTC B2826, GO to G3.
If diagnosing DTC B2827, GO to G5.
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G3 CHECK CIRCUIT VH406 (VT/BN) FOR AN OPEN
- Ignition OFF.
- Disconnect: HVAC Module - DATC 2356b.
- Measure the resistance between HVAC module - DATC C2356b-10, circuit VH406 (VT/BN), harness side and evaporator discharge air temperature sensor C2295-2, circuit VH406 (VT/BN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to G4.
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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G4 CHECK CIRCUIT RH104 (BU/BN) FOR AN OPEN
- Measure the resistance between HVAC module - DATC C2356b-3, circuit RH104 (BU/BN), harness side and evaporator discharge air temperature sensor C2295-1, circuit RH104 (BU/BN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to G7.
No
REPAIR circuit RH104 (BU/BN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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G5 CHECK CIRCUITS VH406 (VT/BN) AND RH104 (BU/BN) FOR A SHORT TOGETHER
- Ignition OFF.
- Disconnect: HVAC Module - DATC 2356b.
- Measure the resistance between evaporator discharge air temperature sensor C2295-2, circuit VH406 (VT/BN), harness side and C2295-1, circuit RH104 (BU/BN), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to G6.
No
REPAIR circuits VH406 (VT/BN) and RH104 (BU/BN) for a short together. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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G6 CHECK CIRCUIT VH406 (VT/BN) FOR A SHORT TO GROUND
- Measure the resistance between HVAC module - DATC C2356b-10, circuit VH406 (VT/BN), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to G7.
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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G7 CHECK THE MODULE CONNECTION
- Carry out the HVAC Module Cold Boot Process. HVAC Module Cold Boot Process
- Carry out the HVAC Module - Electronic Automatic Temperature Control (EATC) and HVAC Module - Dual Automatic Temperature Control (DATC) On-Demand Self Test.
- Operate the system.
- Does the concern return?
Yes
INSTALL a new HVAC module. 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. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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