2004 Dodge Ram Pick up. The instrument lights for the fan controls -heating cooling are real dim. What does it to take to change these lamps out? Pulled the control knobs off but not sure what to do next.

Interior Lights Dimming Circuit Description
VF Displays
When the ignition switch is in the RUN position, the instrument cluster activates its VF display. The instrument cluster also coordinates the display illumination for the radio (IRC), the cellular telephone (PHN), and the climate control Panel (CCP) anytime the ignition switch is in the RUN position.
Incandescent Dimming 1 (INC DIM 1)
The INC DIM 1 consists of lamps powered by CKT 8 (GRY). These are referred to as the park lamp backlighting because they are only active if the park lamps are on and the ambient light sensor indicates darkness.
Incandescent Dimming 2 (INC DIM 2)
The INC DIM 2 output is used as a general interior light source and an illuminated entry feature that provides interior lighting. The INC DIM 2 consists of lamps powered by CKT 1244 (BRN). When one or more of the following conditions occur, the INC DIM 2 lamps will be active:
• The interior lamps switch is active.
• The park lamps are on and the ambient light sensor indicates darkness
• The ignition switch is in the RUN position and the ambient light sensor indicates darkness
• A Class 2 message is received from the body control module (PZM) indicating that the courtesy lamps are active.
Dimming
The instrument cluster controls all of the interior dimming functions. The instrument cluster receives an ambient light level input from the ambient light sensor and determines whether it is light or dark. If the ambient light sensor is inoperative, the instrument cluster will assume a condition of darkness. Dimming of the VF displays is only allowed when the ignition switch is in the RUN position, the park lamps are on, and the ambient light sensor indicates darkness. If all conditions for the VF dimming are met, the instrument cluster uses the input from the potentiometer in the headlamp switch to determine the level of dimming. The dimming level is sent to the radio (IRC), the cellular telephone (PHN), and the climate control panel (CCP) via a Class 2 message. These modules then adjust the dimming level of their VF display. The instrument cluster provides dimming control of the incandescent lighting through the INC DIM 1 and INC DIM 2 outputs. The instrument cluster provides dimming control of the electronic PRNDL LED through CKT 1382 (PPL/WHT). The dimming level will very based on the potentiometer in the headlamp switch whenever the parklamps are on and the ambient light sensor indicates darkness, regardless of the position of the ignition switch.


1998 Cadillac DeVille ' DeVille, Eldorado (VIN E/K) Service Manual ' Body and Accessories ' Lighting Systems ' Diagnostic Information and Procedures ' Document ID: 489166
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Interior Lights Dimming System Check
Step
Action
Normal Result(s)
Abnormal Result(s)*
1
Turn the ignition switch to the OFF position.
Place the interior lamps switch in the ON position.
All incandescent lighting on the INC DIM D2 output turns ON. INC DIM 2 includes all of the lighting on CKT 1244 (BRN), which is the backlighting for the headlamp switch and the floodlighting for the vehicle doors.
Incandescent Lamps Inoperative
2
Place the interior lamps switch in the OFF position.
Turn the ignition switch to the RUN position.
INC DIM 2 lighting turns OFF.
All of the VF displays light. VF displays include the following components (if equipped):
• The radio (IRC)
• The cellular telephone (PHN)
• The driver information center (DIC)
• The instrument cluster (IPC)
• The climate control panel (CCP)
• Vacuum Fluorescent Displays Inoperative - All
• Incandescent Lamps Always On
3
Cover the ambient light sensor with the twilight OFF.
Place the headlamp switch in the PARK position.
The park lamps turn ON.
All of the VF displays dim in order to match the current dimming control level. All of the incandescent lighting for INC DIM 1 and INC DIM 2 light at the current dimming control level. INC DIM 1 includes all of the park lamp backlighting on CKT 8 (GRY) which is composed of the following components:
• The radio (IRC)
• The front cigar lighter
• The steering wheel controls
• The driver information center (DIC)
• The climate control panel (CCP)
• The instrument cluster (IPC)
• The heated seat switches
• The auxiliary blower switches
• The ash tray lamps
• The PRNDL lamp
Exterior Lights System Check
4
Rotate the headlamp switch dimming control in both directions.
All of the VF displays and all of the incandescent lighting dim and brighten in response to the headlamp switch dimming control.
Vacuum Fluorescent Displays Do Not Dim with Instrument Panel Dimmer Switch
* Refer to the appropriate symptom diagnostic table for the applicable abnormal result.

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Your vehicle use's three module's that make up the body control system .
Body Control System Operation
Each of the 3 body control modules integrate a number of functional systems under the control of a single module. Each of the modules is connected to the Class 2 serial data line. Many control signals are implemented by Class 2 messages.
Dash Integration Module (DIM)
The DIM functions include the following functions:
• Power moding control (ignition switch states) over Class 2 serial data line
• Control of headlights and exterior lamps
• Interior lamps incandescent dimming
• Steering wheel controls
• Horn relay control for theft activation
• Lamps On signal with wiper/washer
• Low side temperature for HVAC compressor
• Cooling fan control (power - train cooling)
• Incandescent dimming of dash bulbs control
• Real time clock time keeper
• Battery voltage sense and load management
• Reverse lockout solenoid control
Instrument Panel Module (IPM)
The IPM functions include the following functions:
• Front HVAC air delivery and temperature controls
• Ambient light sensor input and twilight delay input for headlights control
• IP dimmer switch input
• Traction control switch input
• Interior lamps switch input
• Key in ignition switch input from the ignition switch
• Rear compartment lid release switch input
• Ignition switch headlight control
Rear Integration Module (RIM)
The RIM functions include the following functions:
• Heated seat controls
• Rear defogger control
• Park relay controls
• Various controls for the interior lamps
• Reverse control for the backup lamps
• Rear compartment lid release controls
• Retained Accessory Power (RAP) control
• Ajar switch and tamper switch inputs from the rear compartment lid
• Vehicle leveling
Your best bet , take your vehicle to a qualified repair shop , before you cause unnecessary problem's an repair's .

bim or DIM ? the dimmer switch ! Interior Lamps
The interior lamps consists of two groups, lamps that can not be dimmed and lamps that can be dimmed. This first group consists of lamps that may not be dimmed. This includes those lamps that may be manually turned on by placing the interior lamp switch to the DOME position, or by opening a door or a compartment:
• Door courtesy lamps
• Footwell courtesy lamps
• Instrument panel (I/P) compartment lamp
• Overhead console courtesy lamps
• Reading courtesy lamps
• Rear compartment courtesy lamp
• Roof rail courtesy lamps
• Sunshade vanity mirror lamps

Interior Lamps Dimming
This group of interior lighting includes lamps which may be dimmed. This group uses a combination of class 2 controlled illumination and incandescent lamps:
• Air temperature switch
• Cigar lighter lamp
• Door switches
• Driver information center (DIC) switch
• Headlamp switch
• Head-up display (HUD) switch
• Heated seat switches
• HVAC control assembly
• Instrument panel cluster (IPC)
• Memory function switch
• Radio
• Steering wheel controls
• Window switches
For the interior lighting to be dimmed the following conditions must be met:
• A low light level has been detected by the dash integration module (DIM)
• Headlamp switch is placed in to the PARK or HEAD position
• Ignition switch is placed in the ON position
Then all class 2 displays and all incandescent back lighting will be illuminated to the level set by the instrument panel (I/P) dimmer switch. When the I/P dimmer switch is moved from MIN to MAX, all class 2 displays and all incandescent back lighting respond from minimum intensity to maximum brightness.
The DIM supplies battery positive voltage to the coil side of the PRK LP relay in the rear fuse block.
When the I/P dimmer switch is moved from MIN to MAX, then the instrument panel module (IPM), W/CJ2, or climate control panel (CCP), W/C67, applies a message to the class 2 communication circuit to the DIM. The DIM then applies a ground to the park lamp relay control circuit. This energizes the PRK LAMP relay and allows battery positive voltage to be applied through the DIMR fuse to the DIM. The DIM then illuminates the following incandescent lamps through the incandescent dimming output circuit:
• Cigar lighter lamp
• DIC Switch
• Headlamp switch
• HUD switch
• HVAC control assembly
• IPC
• Radio
• Steering wheel controls
The DIM also applies a message to the following class 2 controlled illumination components:
• Drivers door module (DDM)
• HVAC control assembly
• IPC
• Radio
The DDM will then send a message through the simple bus interface (SBI) to the RH front door module (RFDM). The door modules will then illuminate the following components through the incandescent dimming output circuit:
• Air temperature switch
• Heated seat switches (W/KA1)
• Memory function switch (W/A45)
• Power door lock switches
• Power window switches
The ground for these components are provided from the DDM and RFDM.
The following components are grounded at G200:
• Headlamp switch
• HVAC control assembly
• IPC
• Radio
• Steering wheel controls
The following components are grounded at G201:
• Cigar lighter lamp
• DIC Switch
• HUD switch

2004 Dodge Ram 1500 Problems - RepairPal

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Problem with your 2004 Dodge Ram 1500? Search our list of user submitted and RepairPal verified problems and issues.

There are bulbs in the control panel that may have burned out, or the wiring connector could be faulty.

The illumination of these lamps is controlled by the BCM (Body Control Module) and there are numerous other similar lamps throughout the vehicle. It seems almost impossible for these few lamps to be out even after changing out the radio (don't understand why the instrument panel was changed). These miniature bulbs do go bad eventually, so I have no real answer fir your proble.

After the light goes out does it come back on while driving down the road?
If it does this sounds as if you may have a heat sensitive problem at the cruise motor. this has a sensoe that turns the light on when it is engaged. when you turn it off and sits a while does the heat under the hood goes higher expanding the circuts an open circut. You may have to replace the board in the motor.

climate unit is bad

Suggestion would be full coolant system flush and maybe replace thermostat. Sounds like something is plugged.. You have no leaks on the ground correct?