Dodge Ram Truck 1500-2500-3500. Manual — part 2028

RECIRC OVERCURRENT (SINGLE-ZONE) (CONTINUED)

4.

CHECK THE (C801) MODE DOOR 1 DRIVER CIRCUIT FOR A SHORT TO THE (C29) MODE DOOR 2
DRIVER CIRCUIT

Measure the resistance between the (C801) Mode Door 1 Driver cir-
cuit and the (C29) Mode Door 2 Driver circuit in the A/C Heater Con-
trol C1 harness connector.

Is the resistance below 10k ohms?

Yes

>> Repair the (C29) Mode Door 2 Driver circuit for a short to

the (C801) Mode Door 1 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 (C34) COMMON DOOR DRIVER CIRCUIT FOR A SHORT TO THE (C32) RECIRCULATION
DOOR DRIVER CIRCUIT, THE (C61) BLEND DOOR DRIVER CIRCUIT, THE (C801) MODE DOOR 1 DRIVER
CIRCUIT, & THE (C29) MODE DOOR 2 DRIVER CIRCUIT

Measure the resistance between the (C34) Common Door Driver Cir-
cuit and the (C32) Recirculation Door Driver circuit, the (C61) Blend
Door Driver circuit, the (C801) Mode Door 1 Driver circuit, and the
(C29) Mode Door 2 Driver circuit in the A/C Heater Control C1 harness
connector.

Is the resistance below 30.0 ohms on any of the circuits?

Yes

>> Go To 6

No

>> Go To 7

24 - 112

HVAC - ELECTRICAL DIAGNOSTICS

DR/DH

RECIRC OVERCURRENT (SINGLE-ZONE) (CONTINUED)

6.

CHECK THE DOOR DRIVER CIRCUITS WHOSE RESISTANCE WAS BELOW 30.0 OHMS IN THE
PREVIOUS STEP FOR A SHORT TO THE (C34) COMMON DOOR DRIVER CIRCUIT

Disconnect all door actuator harness connectors whose circuit resis-
tance was below 30.0 ohms.

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

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

Yes

>> Repair the door driver circuits with a resistance below 10k

ohms for a short to the (C34) Common 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 all door actuators with a resistance below 30.0

ohms 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).

7.

RUN THE ACTUATOR CIRCUIT TEST

Reconnect the A/C Heater Control C1 harness connector.

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

>> 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 - 113

RECIRC SWITCH FAULT

For a complete wiring diagram Refer to Section 8W.

Theory of Operation

The switch input changes when the switch is pushed down. A stored DTC indicates that the MAX mode switch was
stuck in a pushed position for more than 10 minutes, but has since returned to its normal state. An active DTC
indicates that the MAX mode switch is stuck in a pushed position. An active DTC will prevent proper switch and
status indicator function as evidenced by not being able to turn the status indicator either on if off or off if on.

•

When Monitored:
With the ignition on.

•

Set Condition:
If the MAX mode switch stays closed for 10 minutes.

Possible Causes

A/C HEATER CONTROL

NOTE: This DTC must be active for the result of this test to be valid. Do not perform this test if this DTC is
stored. Refer to HVAC System Test for stored DTC test procedures.

Diagnostic Test

1.

REPLACE THE A/C HEATER CONTROL

Repair

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).

24 - 114

HVAC - ELECTRICAL DIAGNOSTICS

DR/DH

REFRIGERANT PRESSURE RX FAILURE

For a complete wiring diagram Refer to Section 8W.

•

When Monitored:
With the ignition on.

•

Set Condition:
The Powertrain Control Module (PCM) (for gasoline engines) or Engine Control Module (ECM) (for diesel
engines) broadcasts a message on the PCI Bus that provides refrigerant pressure. This DTC will set if the A/C
Heater Control does not receive this message for more than 5 seconds.

Possible Causes

FAULTS PRESENT IN THE POWERTRAIN SYSTEM

PCM NOT BROADCASTING MESSAGE

ECM NOT BROADCASTING MESSAGE

A/C HEATER CONTROL MODULE NOT RECEIVING MESSAGE

Diagnostic Test

1.

VERIFY THAT THE REFRIGERANT PRESSURE RX FAILURE DTC IS ACTIVE

Turn the ignition on.

With the DRBIII

T

, erase HVAC DTCs.

Cycle the ignition switch and wait approximately 30 seconds.

With the DRBIII

T

, read active HVAC DTCs.

Does the DRBIII

T

display: Refrigerant Pressure RX Failure?

Yes

>> Go To 2

No

>> A technician may not have erased this DTC following a module or PCI Bus repair. If possible, verify if

the vehicle was recently in for this type of service. Otherwise, visually inspect the related wiring harness
for chafed, pierced, pinched, and partially broken wires and the wiring harness connectors for broken,
bent, pushed out, and corroded terminals. Repair as necessary.

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

2.

CHECK FOR DTCS IN THE PCM OR ECM

With the DRBIII

T

, read PCM or ECM DTCs.

Does the DRBIII

T

display any DTCs?

Yes (Gasoline Engines)

Diagnose and repair the DTC(s). (Refer to 9 - ENGINE ELECTRICAL DIAGNOSTICS).

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

Yes (Diesel Engines)

Diagnose and repair the DTC(s). (Refer to 9 - ENGINE ELECTRICAL DIAGNOSTICS).

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

No

>> Go To 3

DR/DH

HVAC - ELECTRICAL DIAGNOSTICS

24 - 115