Chrysler 300/300 Touring/300C, Dodge Magnum. Manual — part 2265

Theory of Operation

NOTE: This DTC will display as active if the ignition is not cycled after running the Actuator Circuit Test /
Door Calibration Function. Otherwise, it will display as stored until cleared.
By running the Actuator Circuit Test / Door Calibration Function, the A/C Heater Control can identify up to
three door driver circuits shorted simultaneously. A DTC 72 will set if more than three door driver circuits
are shorted in the same direction (e.g. four door driver circuits all shorted to ground) or if two or more door
driver circuits are shorted with at least one door driver circuit shorted to ignition and one door driver circuit
shorted to ground. To ensure a proper diagnosis, diagnose and repair Actuator Circuit Test faults in the
following order: If present, diagnose and repair DTC 72 first, then DTC 62, then DTC 61, then DTCs 64, 68,
or 71, and finally DTCs 63, 67, or 69. In addition, always test the door driver circuits after each repair by
clearing DTCs, and then running the Actuator Circuit Test / Door Calibration Function, and then checking for
DTCs.

•

When Monitored:
When running the Actuator Circuit Test / Door Calibration Function.

•

Set Condition:
If the A/C Heater Control detects a short to ground on the (C66) Mode Door Common Driver circuit / (C55) Left
Blend Door Common Driver circuit / (C68) Recirculation Door Common Driver circuit.

Possible Causes

(C66) MODE DOOR COMMON DRIVER CIRCUIT / (C55) LEFT BLEND DOOR COMMON DRIVER CIRCUIT /
(C68) RECIRCULATION DOOR COMMON DRIVER CIRCUIT SHORTED TO GROUND

(C66) MODE DOOR COMMON DRIVER CIRCUIT / (C55) LEFT BLEND DOOR COMMON DRIVER CIRCUIT /
(C68) RECIRCULATION DOOR COMMON DRIVER CIRCUIT SHORTED TO OTHER DOOR DRIVER
CIRCUIT(S)

MODE DOOR ACTUATOR

LEFT BLEND DOOR ACTUATOR

RECIRCULATION DOOR ACTUATOR

A/C HEATER CONTROL

Diagnostic Test

1.

CHECK THE (C66) MODE DOOR COMMON DRIVER CIRCUIT, THE (C55) LEFT BLEND DOOR COMMON
DRIVER CIRCUIT, & THE (C68) RECIRCULATION DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO
GROUND

Turn the ignition off.

Disconnect the A/C Heater Control C2 harness connector.

Measure the resistance of the (C66) Mode Door Common Driver Circuit,
the (C55) Left Blend Door Common Driver circuit, and the (C68) Recir-
culation Door Common Driver circuit between ground and the A/C
Heater Control C2 harness connector.

Is the resistance below 10k ohms on any of the circuits?

Yes

>> Repair all circuits with a resistance below 10k ohms for a

short to ground.

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

ELECTRICAL/ELECTRONIC

CONTROL

MODULES/

FRONT CONTROL MODULE - DIAGNOSIS AND TEST-
ING).

No

>> Go To 2

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HVAC - ELECTRICAL DIAGNOSTICS

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2.

CHECK THE (C66) MODE DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO THE (C255) LEFT BLEND
DOOR DRIVER CIRCUIT, (C55) LEFT BLEND DOOR COMMON DRIVER CIRCUIT, (C268) RECIRCULATION
DOOR DRIVER CIRCUIT, & THE (C68) RECIRCULATION DOOR COMMON DRIVER CIRCUIT

Measure the resistance between the (C66) Mode Door Common Driver
circuit and the (C255) Left Blend Door Driver circuit, (C55) Left Blend
Door Common Driver circuit, (C268) Recirculation Door Driver circuit,
and the (C68) Recirculation Door Common Driver circuit in the A/C
Heater Control C2 harness connector.

Is the resistance below 10k ohms on any of the circuits?

Yes

>> Repair all circuits with a resistance below 10k ohms for a

short to the (C66) Mode Door Common Driver circuit.

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

ELECTRICAL/ELECTRONIC

CONTROL

MODULES/

FRONT CONTROL MODULE - DIAGNOSIS AND TEST-
ING).

No

>> Go To 3

3.

CHECK THE (C55) LEFT BLEND DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO THE (C266) MODE
DOOR DRIVER CIRCUIT, (C268) RECIRCULATION DOOR DRIVER CIRCUIT, & THE (C68)
RECIRCULATION DOOR COMMON DRIVER CIRCUIT

Measure the resistance between the (C55) Left Blend Door Common
Driver circuit and the (C266) Mode Door Driver circuit, (C268) Recircu-
lation Door Driver circuit, and the (C68) Recirculation Door Common
Driver circuit in the A/C Heater Control C2 harness connector.

Is the resistance below 10k ohms on any of the circuits?

Yes

>> Repair all circuits with a resistance below 10k ohms for a

short to the (C55) Left Blend Door Common Driver circuit.

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

ELECTRICAL/ELECTRONIC

CONTROL

MODULES/

FRONT CONTROL MODULE - DIAGNOSIS AND TEST-
ING).

No

>> Go To 4

LX

HVAC - ELECTRICAL DIAGNOSTICS

24 - 95

4.

CHECK THE (C68) RECIRCULATION DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO THE (C266)
MODE DOOR DRIVER CIRCUIT & THE (C255) LEFT BLEND DOOR DRIVER CIRCUIT

Measure the resistance between the (C68) Recirculation Door Common
Driver circuit and the (C266) Mode Door Driver circuit and the (C255)
Left Blend Door Driver circuit in the A/C Heater Control C2 harness con-
nector.

Is the resistance below 10k ohms on any of the circuits?

Yes

>> Repair all circuits with a resistance below 10k ohms for a

short to the (C68) Recirculation Door Common Driver cir-
cuit.

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

ELECTRICAL/ELECTRONIC

CONTROL

MODULES/

FRONT CONTROL MODULE - DIAGNOSIS AND TEST-
ING).

No

>> Go To 5

5.

CHECK THE MODE DOOR ACTUATOR CIRCUIT RESISTANCE

Measure the resistance between the (C66) Mode Door Common Driver
Circuit and the (C266) Mode Door Driver circuit in the A/C Heater Con-
trol C2 harness connector.

Is the resistance below 30.0 ohms?

Yes

>> Go To 6

No

>> Go To 7

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6.

CHECK THE (C66) MODE DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO THE (C266) MODE DOOR
DRIVER CIRCUIT

Disconnect the Mode Door Actuator harness connector.

Measure the resistance between the (C66) Mode Door Common Driver
Circuit and the (C266) Mode Door Driver circuit in the A/C Heater Con-
trol C2 harness connector.

Is the resistance below 10k ohms?

Yes

>> Repair the (C66) Mode Door Common Driver Circuit for a

short to the (C266) Mode Door Driver circuit.

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

ELECTRICAL/ELECTRONIC

CONTROL

MODULES/

FRONT CONTROL MODULE - DIAGNOSIS AND TEST-
ING).

No

>> Replace the Mode 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).

7.

CHECK THE LEFT BLEND DOOR ACTUATOR CIRCUIT RESISTANCE

Measure the resistance between the (C55) Left Blend Door Common
Driver Circuit and the (C255) Left Blend Door Driver circuit in the A/C
Heater Control C2 harness connector.

Is the resistance below 30.0 ohms?

Yes

>> Go To 8

No

>> Go To 9

LX

HVAC - ELECTRICAL DIAGNOSTICS

24 - 97