Dodge Ram Truck 1500-2500-3500. Manual — part 2003

BLEND CALIBRATION FAULT (SINGLE-ZONE) (CONTINUED)

For the Manual Temperature Control circuit diagrams (Refer to 24 - HEATING & AIR CONDITIONING - SCHEMAT-
ICS AND DIAGRAMS).

For a complete wiring diagram Refer to Section 8W.

Theory of Operation

NOTE: Diagnose and repair Actuator Circuit Test faults before diagnosing Overcurrent faults and Calibration
faults. Diagnose and repair Overcurrent faults before diagnosing Calibration faults.

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 mea-
sured calibration value is not within the expected range, this fault will set.

For vehicles equipped with electric backlight (EBL), running the HVAC Door Recalibration will cause the EBL status
indicator to flash. If recalibration fails, the EBL status indicator will continue to flash until either the system passes
recalibration or the ignition key is cycled. When the EBL status indicator is flashing, it will not indicate EBL operating
status. However, the EBL mode switch will continue to function normally. When the EBL status indicator is flashing,
the A/C status indicator will not function. However, the A/C mode switch will continue to function normally.

For vehicles not equipped with electric backlight (EBL), no status indicator will flash when running the HVAC Door
Recalibration. If recalibration fails, the A/C status indicator will not function, however, the A/C mode switch will con-
tinue to function normally.

•

When Monitored:
When HVAC Door Recalibration is executed.

•

Set Condition:
If the span of the blend door is found outside the tolerance.

Possible Causes

(C61) BLEND DOOR DRIVER CIRCUIT SHORTED TO GROUND (WILL ALSO SET OVERCURRENT DTCs)

(C61) BLEND DOOR DRIVER CIRCUIT SHORTED TO VOLTAGE (WILL ALSO SET OVERCURRENT DTCs)

(C61) BLEND DOOR DRIVER CIRCUIT OPEN

(C34) COMMON DOOR DRIVER CIRCUIT OPEN

BLEND DOOR ACTUATOR OPEN

BLEND DOOR ACTUATOR BROKEN

BLEND DOOR BOUND UP

BLEND DOOR LINKAGE MISSING, BROKEN

A/C HEATER CONTROL

Diagnostic Test

1.

RUN THE ACTUATOR CIRCUIT TEST

Turn the ignition on.

With the DRBIII

T

in HVAC, select System Tests and then select Actuator Circuit Test. Allow the test to run to com-

pletion before proceeding.

Does the DRBIII

T

display any Actuator Circuit Test fault messages?

Yes

>> Diagnose and repair the fault(s). Refer to *ACTUATOR CIRCUIT TEST DIAGNOSTICS (SINGLE-ZONE)

in this section.

No

>> Go To 2

24 - 12

HVAC - ELECTRICAL DIAGNOSTICS

DR/DH

BLEND CALIBRATION FAULT (SINGLE-ZONE) (CONTINUED)

2.

CHECK FOR DTCS IN THE A/C HEATER CONTROL

NOTE: Diagnose and repair all Overcurrent DTCs before diagnosing Calibration faults.
With the DRBIII

T

, read HVAC DTCs.

Does the DRBIII

T

display any DTCs?

Yes

>> Diagnose and repair the DTC(s). Refer to the Table of Contents in this Section for a complete list of

HVAC related symptoms.

No

>> Go To 3

3.

CHECK THE RESISTANCE BETWEEN THE (C34) COMMON DOOR DRIVER CIRCUIT & THE (C61) BLEND
DOOR DRIVER CIRCUIT

Turn the ignition off.

Disconnect the A/C Heater Control C1 harness connector.

Measure the resistance between the (C34) Common Door Driver cir-
cuit and the (C61) Blend Door Driver circuit in the A/C Heater Control
C1 harness connector.

Is the resistance above 70.0 ohms?

Yes

>> Go To 4

No

>> Go To 6

DR/DH

HVAC - ELECTRICAL DIAGNOSTICS

24 - 13

BLEND CALIBRATION FAULT (SINGLE-ZONE) (CONTINUED)

4.

CHECK (C61) BLEND DOOR DRIVER CIRCUIT FOR AN OPEN

Disconnect the Blend Door Actuator harness connector.

Measure the resistance of the (C61) Blend Door Driver circuit between
the A/C Heater Control C1 harness connector and the Blend Door
Actuator harness connector.

Is the resistance below 5.0 ohms?

Yes

>> Go To 5

No

>> Repair the (C61) Blend Door Driver circuit for an open.

Perform BODY VERIFICATION TEST - VER 1. (Refer to 8
-

ELECTRICAL/ELECTRONIC

CONTROL

MODULES/

FRONT

CONTROL

MODULE

-

DIAGNOSIS

AND

TESTING).

5.

CHECK (C34) COMMON DOOR DRIVER CIRCUIT FOR AN OPEN

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

Is the resistance below 5.0 ohms?

Yes

>> Replace the Blend Door Actuator in accordance with the

Service Information.

Perform BODY VERIFICATION TEST - VER 1. (Refer to 8
-

ELECTRICAL/ELECTRONIC

CONTROL

MODULES/

FRONT CONTROL MODULE - DIAGNOSIS AND TEST-
ING).

No

>> Repair the (C34) Common Door Driver circuit for an open.

Perform BODY VERIFICATION TEST - VER 1. (Refer to 8
-

ELECTRICAL/ELECTRONIC

CONTROL

MODULES/

FRONT

CONTROL

MODULE

-

DIAGNOSIS

AND

TESTING).

24 - 14

HVAC - ELECTRICAL DIAGNOSTICS

DR/DH

BLEND CALIBRATION FAULT (SINGLE-ZONE) (CONTINUED)

6.

CHECK FOR A BROKEN BLEND DOOR ACTUATOR

Remove the Blend Door Actuator from the A/C Heater Housing Assembly.

Disconnect the Blend Door Actuator harness connector.

By hand, attempt to rotate the actuator in both directions.

Does the actuator turn in either direction?

Yes

>> Replace the Blend Door Actuator in accordance with the Service Information.

Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL
MODULES/FRONT CONTROL MODULE - DIAGNOSIS AND TESTING).

No

>> Go To 7

7.

CHECK FOR MISSING & BROKEN ACTUATOR LINKAGE & THE DOOR FOR BINDING & A LOSS OF
RANGE

Inspect the A/C Heater Housing Assembly for missing and broken actuator linkage.

Inspect the linkage and the actuator for broken and missing teeth.

Check the door for binding and a loss of full range.

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

Yes

>> Repair as necessary in accordance with the Service Information.

Perform BODY VERIFICATION TEST - VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL
MODULES/FRONT CONTROL MODULE - DIAGNOSIS AND TESTING).

No

>> 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/FRONT CONTROL MODULE - DIAGNOSIS AND TESTING).

DR/DH

HVAC - ELECTRICAL DIAGNOSTICS

24 - 15