Chrysler 300/300 Touring/300C, Dodge Magnum. Manual — part 2273

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 more than three door driver circuits 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 voltage and one door driver circuit shorted to ground.

Possible Causes

MORE THAN THREE DOOR DRIVER CIRCUITS SHORTED TO VOLTAGE

MORE THAN THREE DOOR DRIVER CIRCUITS SHORTED TO GROUND

TWO OR MORE DOOR DRIVER CIRCUITS SHORTED WITH AT LEAST ONE SHORTED TO IGNITION AND
ONE SHORTED TO GROUND

MODE DOOR ACTUATOR

LEFT BLEND DOOR ACTUATOR

RECIRCULATION DOOR ACTUATOR

A/C HEATER CONTROL

Diagnostic Test

1.

CHECK THE (C266) MODE DOOR DRIVER CIRCUIT, (C66) MODE DOOR COMMON DRIVER CIRCUIT,
(C255) LEFT BLEND DOOR DRIVER CIRCUIT, (C55) LEFT BLEND DOOR COMMON DRIVER CIRCUIT,
(C268) RECIRCULATION DOOR DRIVER CIRCUIT, & (C68) RECIRCULATION DOOR COMMON DRIVER
CIRCUIT FOR A SHORT TO VOLTAGE

Turn the ignition off.

Disconnect the A/C Heater Control C2 harness connector.

Turn the ignition on.

Measure the voltage of the (C266) Mode Door Driver circuit, (C66)
Mode Door Common Driver circuit, (C255) Left Blend Door Driver cir-
cuit, (C55) Left Blend Door Common Driver circuit, (C268) Recirculation
Door Driver circuit, and the (C68) Recirculation Door Common Driver
circuit.

Is the voltage above 0.2 volts on any of the circuits?

Yes

>> Repair all circuits with voltage above 0.2 volts for a short to

voltage.

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

LX

2.

CHECK THE (C266) MODE DOOR DRIVER CIRCUIT, (C66) MODE DOOR COMMON DRIVER CIRCUIT,
(C255) LEFT BLEND DOOR DRIVER CIRCUIT, (C55) LEFT BLEND DOOR COMMON DRIVER CIRCUIT,
(C268) RECIRCULATION DOOR DRIVER CIRCUIT, & (C68) RECIRCULATION DOOR COMMON DRIVER
CIRCUIT FOR A SHORT TO GROUND

Turn the ignition off.

Measure the resistance of the (C266) Mode Door Driver circuit, (C66)
Mode Door Common Driver circuit, (C255) Left Blend Door Driver cir-
cuit, (C55) Left Blend Door Common Driver circuit, (C268) Recirculation
Door Driver circuit, and the (C68) Recirculation Door Common Driver
circuit between ground and the A/C Heater Control C2 harness connec-
tor.

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 3

3.

CHECK THE (C266) MODE DOOR 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 (C266) Mode Door 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 Con-
trol 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 (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

>> Go To 4

LX

HVAC - ELECTRICAL DIAGNOSTICS

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4.

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 5

5.

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

Measure the resistance between the (C255) Left Blend Door Driver cir-
cuit and the (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 (C255) Left Blend Door 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 6

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HVAC - ELECTRICAL DIAGNOSTICS

LX

6.

CHECK THE (C55) LEFT BLEND DOOR COMMON DRIVER CIRCUIT FOR A SHORT TO THE (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 (C268) Recirculation Door Driver circuit and the
(C68) Recirculation Door Common Driver circuit in the A/C Heater Con-
trol 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 7

7.

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 8

No

>> Go To 9

LX

HVAC - ELECTRICAL DIAGNOSTICS

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