B1926-12

B1926-12-MODE/TEMPERATURE DOOR VOLTAGE REFERENCE - CIRCUIT SHORT TO BATTERY





For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

After the initial installation of the A/C Heater Control, the controller is calibrated to each individual blend/mode door actuator. The actuators are connected to the A/C Heater Control by a dedicated five-wire sensor and control circuits. The actuator can move the blend/mode-air doors in two directions. When the A/C Heater Control pulls the voltage on one side of the control circuit high and the other low, the door actuator will move in one direction. When the A/C Heater Control reverses the polarity of the voltage to the motor, the door actuator moves in the opposite direction. Once the A/C Heater Control makes the voltage to both control circuits high or low, the door actuator will stop its movement and stay in that position. The blend/mode door actuator contains a three wire potentiometer, which the A/C Heater Control uses to monitor the relative position of the blend/mode air doors. The A/C Heater Control learns the blend-air door stop positions during the calibration procedure.

- When Monitored:
Continuously with the ignition on.

- Set Condition:
The A/C Heater Control detects a short voltage on the 5 Volt Supply circuit. If the A/C Heater Control detects a valid voltage, the DTC will change from Active to Stored and will stay in the controllers memory for 100 ignition cycles.





Always perform the HVAC Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview.

1. CHECK IF DTC IS ACTIVE
1. Ignition on, engine not running.
2. With the scan tool, read HVAC DTCs.

Is this DTC active?

Yes

- Go To 2

No

- Go To 3

2. CHECK THE (C) 5 VOLT SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE




1. Turn the ignition off to the lock position.
2. Disconnect the A/C Heater Control harness connector.
3. Disconnect the Mode Door and Blend Door Actuator harness connectors.
4. Ignition on, engine not running.
5. Measure the voltage of the (C) 5 Volt Supply circuit.

Is there any voltage present?

Yes

- Repair the (C) 5 Volt Supply circuit for a short to voltage.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Replace and program the A/C Heater Control. A/C And Heater Control - Removal.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

3. CHECK THE WIRING AND CONNECTORS
1. The conditions necessary to set the DTC are not present at this time.
2. With the scan tool, check the Environmental Data to help identify the conditions in which the DTC was set.
3. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.
4. Wiggle the wiring and connectors while checking for shorted and open circuits.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Test complete.