B1A68:15

Climate Control System

Pinpoint Test E: DTCs B1A68:11 and B1A68:15

Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information [1][2]Diagrams By Number.

Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information [1][2]Diagrams By Number.

Normal Operation

Under normal operation, the ambient 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 B1A68:11 (Ambient Temperature Sensor: Circuit Short to Ground)- The module senses lower than expected voltage on the sensor feedback circuit, indicating a short to ground.

- DTC B1A68:15 (Ambient Temperature Sensor: Circuit Short to Battery or Open)- The module senses greater than expected voltage on the sensor feedback circuit, indicating a short to voltage or an open circuit or sensor.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- Ambient air temperature sensor

- HVAC module

PINPOINT TEST E : DTCs B1A68:11 AND B1A68:15

E1 CHECK THE SENSOR RESISTANCE

- Ignition OFF.

- Disconnect: Ambient Air Temperature Sensor C132.

- Measure the resistance between the ambient air temperature sensor C132 terminals and compare to the table below.

Ambient Temperature Resistance -40°C (-40°F) 832,519-1,017,523 ohms -15°C (5°F) 199,325-220,307 ohms 0°C (32°F) 91,058-100,644 ohms 15°C (59°F) 44,435-49,113 ohms 25°C (77°F) 28,500-31,500 ohms 35°C (95°F) 18,730-20,701 ohms 60°C (140°F) 7,171-7,925 ohms 85°C (185°F) 3,110-3,438 ohms






Is the resistance within the specified values for the temperatures?

Yes
GO to E2.

No
INSTALL a new ambient air temperature sensor. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

E2 CHECK THE SENSOR OUTPUT VOLTAGE

- Ignition ON.

- Measure the voltage between ambient air temperature sensor C132-1, circuit VH407 (YE/GN), harness side and C132-2, circuit RH111 (GY/BU), harness side.





Is the voltage between 4.7 and 5.1 volts?

Yes
INSTALL a new ambient air temperature sensor. CLEAR the DTCs. REPEAT the self-test. If code returns, GO to E8.

No

For DTC B1A61:15, GO to E3.

For DTC B1A61:11, GO to E6.

E3 CHECK CIRCUIT VH407 (YE/GN) FOR A SHORT TO VOLTAGE

- Ignition OFF.

- Disconnect: HVAC Module C294A.

- Ignition ON.

- Measure the voltage between HVAC module C294A-12, 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.

E4 CHECK CIRCUIT VH407 (YE/GN) FOR AN OPEN

- Ignition OFF.

- Measure the resistance between HVAC module C294A-12, circuit VH407 (YE/GN), harness side and ambient air 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.

E5 CHECK CIRCUIT RH111 (GY/BU) FOR AN OPEN

- Measure the resistance between HVAC module C294A-4, circuit RH111 (GY/BU), harness side and ambient air temperature sensor C132-2, circuit RH111 (GY/BU), harness side.





Is the resistance less than 5 ohms?

Yes
GO to E8.

No
REPAIR circuit RH111 (GY/BU) for an open. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

E6 CHECK CIRCUIT VH407 (YE/GN) FOR A SHORT TO CIRCUIT RH111 (GY/BU)

- Ignition OFF.

- Disconnect: HVAC Module C294A.

- Measure the resistance between ambient air temperature sensor C132-1, circuit VH407 (YE/GN), harness side and C132-2, circuit RH111 (GY/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 RH111 (GY/BU). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

E7 CHECK CIRCUIT VH407 (YE/GN) FOR A SHORT TO GROUND

- Measure the resistance between HVAC module C294A-12, 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.

E8 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. 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.