B1043

B1043-PANEL MODE DOOR 1 CONTROL CIRCUIT OPEN







Theory of Operation

After the initial installation of the A/C Heater Control, the controller is calibrated to each individual blend/mode door actuator. These calibrations are stored as in the number of pulses it takes to move the door from one stop to another. The A/C Heater Control drives the Door Actuators by the use of Door Driver circuit and a Common Door Driver circuit and monitors all door actuator pulses to detect door movement in both directions. Most of the door actuators share a common door driver circuit but each door actuator has its own unique driver circuit. Due to shared circuitry, similar DTCs can set at the same time for multiple actuators depending upon the type of circuit malfunction, its location, and the direction the actuator is moving when the malfunction is present.

- When Monitored:
With the ignition on and when a HVAC Actuator Calibration Test is performed.

- Set Condition:
If an HVAC Actuator Calibration Test is performed the A/C Heater Control detects there are no feedback pulses detected in that direction, the controller commands the actuator in the opposite direction. If no feedback pulses are detected in either direction this DTC will set. If the A/C Heater Control detects a valid pulse feedback in both directions, 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. HVAC Pre-Diagnostic Troubleshooting Procedure.

1. CHECK FOR OTHER DTCS
1. Ignition on, engine not running.
2. With the scan tool, read HVAC DTCs.

Is there more than one Door Control Circuit Open DTC present?

Yes

- Repair the (C34) Common Door Driver circuit for an open.NOTE: Due to the common shared driver circuit, probable area of concern is the splice, or from the splice to the A/C Heater Control harness connector. Make sure to check all inline connectors.

No

- Go To 2

2. 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 4

No

- Go To 3

3. PERFORM HVAC ACTUATOR CALIBRATION TEST
1. With the scan tool, perform the HVAC Actuator Calibration Test.

Did this DTC change from Stored to Active while performing the HVAC Actuator Calibration Test?

Yes

- Go To 4

No

- Go To 7

4. CHECK THE MODE DOOR ACTUATOR




1. Turn the ignition off to the lock position.
2. Disconnect the A/C Heater Control C1 harness connector.
3. Measure the resistance between the (C35) Mode Door Driver circuit and the (C34) Common Door Driver circuit.

Is the resistance 38.0 Ohms (± 5.0 Ohms)?

Yes

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

No

- Go To 5

5. CHECK THE (C35) MODE DOOR DRIVER CIRCUIT FOR AN OPEN




1. Turn the ignition off to the lock position.
2. Disconnect the Mode Door Actuator harness connector.
3. Measure the resistance of the (C35) Mode Door Driver circuit between the A/C Heater Control C1 harness connector and the Mode Door Actuator harness connector.

Is the resistance above 1.0 Ohm?

Yes

- Repair the (C35) Mode Door Driver circuit for an open or high resistance.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Go To 6

6. CHECK THE (C34) COMMON DOOR DRIVER CIRCUIT FOR AN OPEN




1. Measure the resistance of the (C34) Common Door Driver circuit between the A/C Heater Control C1 harness connector and the Mode Door Actuator harness connector.

Is the resistance above 1.0 Ohm?

Yes

- Repair the (C34) Common Door Driver circuit for an open or high resistance.NOTE: Probable location is the wiring harness splice or the wiring between the splice and the door actuator.

- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

No

- Replace the Mode Door Actuator.
- Perform the HVAC VERIFICATION TEST. HVAC Verification Test.

7. CHECK THE WIRING AND CONNECTORS
1. The conditions necessary to set the DTC are not present at this time.
2. Using 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.