Intrepid V6-27L VIN U: Body Control Module - System Description
A feedback signal failure can occur on the blend or mode door. The body control module monitors the feedback signal to check the position of the
actuator. The body control module not only checks the level of the signal but also how much the voltage changes.
A feedback failure can occur if there is a short or open circuit in the wiring, a bad actuator, a bad body control module, a bad HVAC unit door or
connecting linkage. The easiest way to diagnose this is to use the DRB to actuate the blend or mode door. Note that the feedback voltage of the
actuator should smoothly change as the actuator is moved. A sudden change in the feedback voltage to a 5.0-volt or a 0.0-volt level indicates the
actuator is bad. A fixed feedback voltage that is less than 5.0 volts or greater than 0.0 volts without a stall failure, or a short failure indicates that
the actuator, the HVAC unit door, or a connecting mechanical linkage is jammed thereby preventing movement. A feedback signal voltage that
stays ON 5.0 volts or 0.0 volts indicates a wiring or body control module problem. The feedback voltage should always be less than 5.0 volts and
greater than 0.0 volts.
The feedback trouble code can also occur from lack of actuator travel. This can be checked by confirming that the feedback signal smoothly
changes when the actuator is moved with the DRB. If the signal is OK, the door travel is not correct. The actuator must be removed and the HVAC
unit door mechanically checked for proper operation. Typical problems that prevent door movement include screws dropped in the HVAC unit or
warped doors. Replace any part that is found defective.
Rear Window Defogger
When the BCM receives a rear defogger request from the climate control head (either ATC or manual) the BCM will activate the rear window
defogger relay for 15 minutes. If the BCM receives another rear defogger request while the relay is still activated, the relay will be de-activated. If
the relay is allowed to time out (full 15 minutes), further requests during the same ignition ON period will cause the BCM to activate the relay for
7.5 minutes
Exterior Lighting System
Exterior Lighting Battery Saver
The BCM monitors the status of and controls the park lamp, bead lamp and fog lamp relay's. If any exterior lamps are left ON after the ignition is
turned OFF, the BCM will turn them OFF after 10 minutes.
Headlamp Delay
The headlamp time delay operates when the ignition switch is turned OFF while the headlamps are still ON, and the headlamps are then turned
OFF within 45 seconds after the ignition is OFF. This will provide a 90-second time delay before turning OFF the headlamps.
Headlamp Switch
The headlight switch on LH vehicles use a Multiplexed (MUX) circuit to the BCM. The BCM will then control the park lamp, head lamp and fog
lamp relay's based on this input.
Fog Lamp Control
The body control module controls the operation of the fog lamp relay which controls the fog lamps. The fog lamps can only be ON if the park or
low beam headlamps are ON. If the high beams are turned ON, the fog lamps will automatically be turned OFF.
Auto Headlamps
The headlamps and park/tail lamps will be activated by the BCM when the headlamp switch is in the auto mode. To activate the auto headlamps
the BCM requires that: (1) the headlamp switch is in the 'A' position, (2) the engine is running, and (3) the light level sensed through the sun load
sensor falls below the calibrated level.
Interior Lighting
The body controller has direct control over the majority of the vehicle's courtesy lamps. The body computer will illuminate the courtesy lamps
under any of the following conditions:
1. Any door is ajar.
2. The courtesy lamp switch on the instrument panel is closed.
3. A Remote Keyless entry unlock message is received. If the interior lamps are left ON after the ignition is turned OFF, the BCM will turn them
OFF after 1 hour or until either the dome lamp switch or door ajar switch changes state.
Illuminated Entry
Illuminated entry will be initiated when the customer enters the vehicle by unlocking the doors with the key fob, or with the key if the vehicle is
equipped with vehicle theft alarm. Upon exiting the vehicle, if the lock button is pressed with a door open, illuminated entry will cancel when the
