Pinpoint Test E: DTC B1A68
Climate Control System
Pinpoint Tests
Pinpoint Test E: DTC B1A68
Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, the ambient temperature sensor receives a ground from the HVAC module through circuit RH107 (GN/BU). A 5-volt reference voltage is supplied to the ambient temperature sensor from the HVAC module through circuit VH407 (YE/GN).
- DTC B1A68:11 Ambient 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 B1A68:15 Ambient 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
- Ambient temperature sensor
- HVAC module
PINPOINT TEST E: DTC B1A68
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E1 CHECK THE SENSOR RESISTANCE
- Ignition OFF.
- Disconnect: Ambient Temperature Sensor C132.
- Measure the resistance between the ambient temperature sensor C132 terminals.
- Is the resistance within the specified values for these temperature ranges: 10-20°C (50-68°F), 37,000-58,000 ohms; 20-30°C (68-86°F), 24,000-37,000 ohms; 30-40°C (86-104°F), 16,000-24,000 ohms?
Yes
GO to E2.
No
INSTALL a new ambient temperature sensor. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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E2 CHECK THE SENSOR OUTPUT VOLTAGE
- Ignition ON.
- Measure the voltage between ambient temperature sensor C132-1, circuit VH407 (YE/GN), harness side and C132-2, circuit RH107 (GN/BU), harness side.
- Is the voltage between 4.7 and 5.1 volts?
Yes
INSTALL a new ambient temperature sensor. CLEAR the DTCs. REPEAT the self-test. If code returns, GO to E8.
No
If diagnosing DTC B1A61:15, GO to E3.
If diagnosing DTC B1A61:11, GO to E6.
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E3 CHECK CIRCUIT VH407 (YE/GN) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: HVAC Module C228a/C2356a.
- Ignition ON.
- Measure the voltage between HVAC module C228a/C2356a-2, circuit VH407 (YE/GN), harness side and ground.
- Is any voltage present?
Yes
REPAIR circuit VH407 (YE/GN) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
No
GO to E4.
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E4 CHECK CIRCUIT VH407 (YE/GN) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between HVAC module C228a/C2356a-2, circuit VH407 (YE/GN), harness side and ambient temperature sensor C132-1, circuit VH407 (YE/GN), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to E5.
No
REPAIR circuit VH407 (YE/GN) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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E5 CHECK CIRCUIT RH107 (GN/BU) FOR AN OPEN
- Measure the resistance between HVAC module C228a/C2356a-10, circuit RH107 (GN/BU), harness side and ambient temperature sensor C132-2, circuit RH107 (GN/BU), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to E8.
No
REPAIR circuit RH107 (GN/BU) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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E6 CHECK CIRCUIT VH407 (YE/GN) FOR A SHORT TO CIRCUIT RH107 (GN/BU)
- Ignition OFF.
- Disconnect: HVAC Module C228a/C2356a.
- Measure the resistance between ambient temperature sensor C132-1, circuit VH407 (YE/GN), harness side and C132-2, circuit RH107 (GN/BU), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to E7.
No
REPAIR circuit VH407 (YE/GN) for a short to circuit RH107 (GN/BU). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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E7 CHECK CIRCUIT VH407 (YE/GN) FOR A SHORT TO GROUND
- Measure the resistance between HVAC module C228a/C2356a-2, circuit VH407 (YE/GN), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to E8.
No
REPAIR circuit VH407 (YE/GN) for a short to ground. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.
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E8 CHECK THE MODULE CONNECTION
- Carry out the HVAC Module Cold Boot Process. HVAC Module Cold Boot Process
- Carry out the HVAC Module On-Demand Self Test. Alternate Diagnostic Methods - HVAC Module
- 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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