RAM 2500 Truck 2WD V8-5.7L VIN D (2004)
SYSTEM CONTROLS
The Heater Control Module:
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is fully addressable with the DRBIII(R).
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communicates over the Programmable Communication Interface Multiplex System (PCI) Bus.
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controls blower motor operation, providing four blower speeds (Low, M1, M2, & High).
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controls heated mirror and EBL operation (if equipped).
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controls electric door actuator operation.
The A/C-Heater Control Module:
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is fully addressable with the DRBIII(R).
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communicates over the Programmable Communication Interface Multiplex System (PCI) Bus.
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uses input from the evaporator temperature sensor to prevent evaporator freeze up while maintaining optimum cooling performance.
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provides an A/C request to the Powertrain Control Module (PCM) over the PCI Bus when compressor operation is desired.
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controls blower motor operation, providing four blower speeds (Low, M1, M2, & High).
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controls heated mirror and EBL operation (if equipped).
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controls electric door actuator operation.
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A simplified control system for operation of the mode, recirculation, and temperature control actuators provides positive positioning without the
complexity of feedback from position sensors. The A/C - Heater Control Module knows the number of operating actuator revolutions required for
full door travel as well as the number of actuator commutator pulses per revolution. Using these parameters, the A/C -Heater Control Module runs
the actuator for the number of commutator pulses that correspond to the desired door position. To maintain accuracy, the system recalibrates itself
periodically at known zero and full travel conditions.
The Single-Zone HVAC system uses:
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one, two-wire electric blend door actuator.
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two, two-wire electric mode door actuators.
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one, two-wire electric recirculation door actuator.
The Dual-Zone HVAC system uses:
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two, two-wire electric blend door actuators.
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two, two-wire electric mode door actuators.
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one, two-wire electric recirculation door actuator.
SYSTEM REVISIONS
The 2004 DR, HVAC system remains carryover from 2003.
SYSTEM DIAGNOSTICS
Fault detection is through active and stored Diagnostic Trouble Codes (DTCs) . DTCs are displayed by the DRBIII(R).
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Active DTCs are those which currently exist in the system. The condition causing the fault must be repaired in order to clear this type of DTC.
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Stored DTCs are those which occurred in the system since the A/C-Heater Control Module received the last "clear diagnostic info" message.
The A/C Cooldown Test:
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is actuated with the DRBIII(R).
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checks A/C system performance based on evaporator temperature sensor input.
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will not run if ambient temperature is below 12.7° C (55° F).
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will pass if the evaporator temperature drops 6.7° C (20° F) within two minutes of starting the test.
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faults display on the DRBIII(R) as test messages only after running the test.
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faults will not display on the DRBIII(R) as Diagnostic Trouble Codes.
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will cause the A/C mode switch status indicator to flash while the test is running.
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If the test fails, the status indicator will continue to flash until either the test returns passed or the ignition key is cycled. It will also prevent the
EBL mode switch status indicator from indicating EBL operating status. However, the EBL mode switch will continue to function in this state.
The HVAC Door Recalibration function:
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is actuated with the DRBIII(R).
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monitors for door span faults.
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faults display on the DRBIII(R) as test messages only after running the test.
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faults will not display on the DRBIII(R) as Diagnostic Trouble Codes.
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will cause the EBL mode switch status indicator to flash while the test is running.
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If the test fails, the status indicator will continue to flash until either the test returns passed or the ignition key is cycled. It will also prevent the A/C
mode switch status indicator from indicating A/C operating status. However, the A/C mode switch will continue to function in this state.
The Actuator Circuit Test:
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is actuated with the DRBIII(R).
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monitors for shorted actuator circuits.
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allows service to easily diagnose and troubleshoot up to three simultaneous shorts.
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supplements the continuous diagnostics on the actuator drive system.
