51-RECIRC DOOR RANGE TOO SMALL (MTC)

For a complete wiring diagram Refer to Section 8W.

Theory of Operation

NOTE: Diagnose and repair Actuator Circuit Test faults (DTC 61, 62, 63, 64, 65, 66, 67, 68, 69, 71, and 72) before diagnosing Overcurrent faults (DTC 41, 42, 43, and 44) and Calibration faults (DTC 18, 21, 22, 23, 24, 25, 45, 46, 47, 48, 51, 52, 53, 54, 55, and 56). Diagnose and repair Overcurrent faults (DTC 41, 42, 43, and 44) before diagnosing Calibration faults (DTC 18, 21, 22, 23, 24, 25, 45, 46, 47, 48, 51, 52, 53, 54, 55, and 56).

The purpose of actuator calibration is to determine the total span of door travel between physical stops. To calibrate the actuator, the A/C Heater Control first moves the door to its soft stop, and then counts the number of pulses it takes to move the door to its other stop. An expected range of span is stored in the control's memory. If the A/C Heater Control detects too few commutator pulses when calibrating the recirculation door, this DTC will set.

When Monitored:
During actuator calibration.
Set Condition:
If the A/C Heater Control detects too few commutator pulses when calibrating the recirculation door.

Possible Causes

ACTUATOR CIRCUIT TEST FAULTS PRESENT

OVERCURRENT FAULTS PRESENT

RECIRCULATION DOOR BINDING, OBSTRUCTED

RECIRCULATION DOOR ACTUATOR

A/C HEATER CONTROL

Diagnostic Test

1. VERIFY IF ANY ACTUATOR CIRCUIT TEST FAULTS OR OVERCURRENT FAULTS ARE PRESENT

Turn the ignition on.
Actuate the Clear DTC function by performing the following:

Turn the blower control on.
Press the A/C mode switch down, turn the blower control to off, wait until both LEDs illuminate (approximately 5 seconds) and then release the A/C mode switch.
When the A/C status indicator begins displaying DTCs, set the Mode switch to the floor position, simultaneously press the A/C mode switch and the EBL mode switch down until both LEDs start flashing (approximately 5 seconds) and then release the mode switches. Stored DTCs will clear from memory in approximately two seconds.

Turn the ignition off, wait 10 seconds, and turn the ignition on.
Actuate the Actuator Circuit Test / Door Calibration Function by performing the following:

Turn the blower control off.
Press and hold the EBL mode switch down and then turn the blower control on. Continue to hold the EBL mode switch down until the EBL status indicator begins flashing. Then, release the EBL mode switch. While the test / function is running, the EBL status indicator will flash once per second. If the test / function passes, the EBL status indicator will stop flashing. If the test / function fails, the A/C and EBL status indicators will flash alternately. Allow the test / function to run to completion before proceeding.

Actuate the Display DTC function by performing the following:

Turn the blower control on.
Press the A/C mode switch down, turn the blower control to off, wait until both LEDs illuminate (approximately 5 seconds) and then release the A/C mode switch.

NOTE: The A/C status indicator displays active DTCs when the EBL status indicator is not illuminated and stored DTCs when the EBL status indicator is illuminated.

Read DTCs from the A/C status indicator.

Does the A/C status indicator display any of the following DTCs: 41, 42, 43, 44, 61, 62, 63, 64, 65, 66, 67, 68, 69, 71, or 72?

Yes

As present, diagnose and repair the faults in the following order: DTC 72 first, then DTC 62, then DTC 61, then DTCs 64, 66, 68, or 71, then DTCs 63, 65, 67, or 69, and finally DTCs 41, 42, 43, or 44. Refer to the Table Of Contents in this section for a complete list of HVAC related symptoms.

Go To 2

2. INSPECT ACTUATOR & HOUSING ASSEMBLY FOR A CONDITION CAUSING THE RECIRCULATION DOOR TO BIND

Turn the ignition off.
Inspect the actuator, linkage, and housing assembly for a condition causing the recirculation door to bind.

Are there any physical or mechanical problems with the door, housing, linkage, or actuator?

Yes

Repair as necessary in accordance with the Service Information.

Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

Go To 3

3. CHECK RECIRCULATION DOOR TRAVEL

Remove the Recirculation Door Actuator from the A/C Heater Housing Assembly.
By hand, attempt to rotate the door in both directions. The door should operate smoothly in both directions over the entire span of travel (approximately 85 degrees).

Does the door operate smoothly in both directions over the entire span of travel?

Yes

Replace the Recirculation Door Actuator in accordance with the Service Information. Then, Go To 4.

Repair as necessary in accordance with the Service Information.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

4. VERIFY IF THE FAULT IS STILL PRESENT

Turn the ignition on.
Actuate the Clear DTC function by performing the following:

Turn the blower control on.
Press the A/C mode switch down, turn the blower control to off, wait until both LEDs illuminate (approximately 5 seconds) and then release the A/C mode switch.
When the A/C status indicator begins displaying DTCs, set the Mode switch to the floor position, simultaneously press the A/C mode switch and the EBL mode switch down until both LEDs start flashing (approximately 5 seconds) and then release the mode switches. Stored DTCs will clear from memory in approximately two seconds.

Turn the ignition off, wait 10 seconds, and turn the ignition on.
Actuate the Actuator Circuit Test / Door Calibration Function by performing the following:

Turn the blower control off.
Press and hold the EBL mode switch down and then turn the blower control on. Continue to hold the EBL mode switch down until the EBL status indicator begins flashing. Then, release the EBL mode switch. While the test / function is running, the EBL status indicator will flash once per second. If the test / function passes, the EBL status indicator will stop flashing. If the test / function fails, the A/C and EBL status indicators will flash alternately. Allow the test / function to run to completion before proceeding.

Actuate the Display DTC function by performing the following:

Turn the blower control on.
Press the A/C mode switch down, turn the blower control to off, wait until both LEDs illuminate (approximately 5 seconds) and then release the A/C mode switch.

NOTE: The A/C status indicator displays active DTCs when the EBL status indicator is not illuminated and stored DTCs when the EBL status indicator is illuminated.

Read DTCs from the A/C status indicator.

Does the A/C status indicator display DTC 51?

Yes

Replace the A/C Heater Control in accordance with the Service Information.

Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).