Dodge Ram 2004 Service Manual page 378

HEATING & A/C
A/C SWITCH FAULT (STORED) —
CHECKSUM FAILURE (STORED)
When Monitored: At every power up (five seconds after ignition is on).
Set Condition: This DTC will set if the calculated check sum does not match the stored
value.
DEFOG SWITCH FAULT (STORED)
When Monitored: With the ignition on.
Set Condition: This DTC will set if the EBL switch stays closed for 10 minutes.
ENGINE GAUGE RX FAILURE (STORED)
When Monitored: With the ignition on.
Set Condition: This DTC will set if the A/C - Heater Control Module does not receive the
message from the PCM for more than 5 seconds. This message provides Battery Voltage,
Battery Temperature, and Engine Coolant Temperature.
EVAPORATOR TEMPERATURE SENSOR CIRCUIT OPEN (STORED)
When Monitored: With the ignition on.
Set Condition: This DTC will set if the A/C - Heater Control Module sees voltage above
4.9 volts on the Evaporator Temperature Sensor Signal circuit.
EVAPORATOR TEMPERATURE SENSOR CIRCUIT SHORTED (STORED)
When Monitored: With the ignition on.
Set Condition: This DTC will set if the A/C - Heater Control Module sees voltage below
0.06 volts on the Evaporator Temperature Sensor Signal circuit.
LOOPBACK TEST FAILURE (STORED)
When Monitored: When the A/C - Heater Control Module executes an internal loopback
test.
Set Condition: If the A/C - Heater Control Module fails to send a message, or none of the
expected messages arrive for 5 seconds, an internal loopback test is executed. If the
internal loopback test fails, the DTC will set.
MODE 1 OVERCURRENT (STORED)
When Monitored: When actuator movement is requested.
Set Condition: This DTC will set if the A/C - Heater Control Module detects an excessive
current draw on any of the door driver circuits while attempting to drive this actuator.
Only one overcurrent DTC can set per ignition cycle.
MODE 2 OVERCURRENT (STORED)
When Monitored: When actuator movement is requested.
Set Condition: This DTC will set if the A/C - Heater Control Module detects an excessive
current draw on any of the door driver circuits while attempting to drive this actuator.
Only one overcurrent DTC can set per ignition cycle.
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