I need to know what controls the lights that illuminate the radio and heater controls on a 1998 Cadillac Seville. the displays are working. Just not the buttons on each are not lit

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.

No, the Powertrain Control Module only does powertrain, but can prevent starting.

Lights and locks are the domain of the Body Control Module. Having said that, your Cadillac has dozens of large and small modules.

Check the fuses,

Cadillac Seville (1998) - fuse box diagram - Auto Genius

https://www.autogenius.info > cadillac-seville-1998-fus...

Feb 7, 2018 - Cadillac Seville (1998) - fuse box diagram. Year of production: 1998. Engine Compartment Bussed Electrical Center (BEC).

Fuse Box Diagram Cadillac Seville (1998-2004) - Fuse-box.info

https://fuse-box.info > cadillac > cadillac-seville-1998-2...
Here you will find fuse box diagrams of Cadillac Seville 1998, 1999, 2000, 2001, 2002, 2003 and 2004, get information about the location of the fuse panels ...

Anything else will require an auto electrician with a pro grade scan tool computer.

check wiring

Blown bulb if the radio works.

Make sure you don't have the instrument panel dimmed all the way down if so turn it up, then if that doesnt work make sure your head lights are turning on when they are suposed to, if not you may have a bad light sensor on the dash or bad headlamp switch.

sounds like blending door is not moving, or stuck in place, some use a relay and fuse look in fuse box ,try it with car off and switch it from one to the other and see if you hear whats going on. it may also use a vacuum control.

Gosh, where do you live? It must be a pretty mild climate. Here in Montana I would have parked the Seville until I saved up the funds to have that '92 state of the art heater control system looked at-like tomorrow's tomorrow. Being it has been on the road for 20 years now, the control unit may need replacing. Only someone familiar with Cadillac controls would know all the ins and outs of the system. Try and get an estimate on repairs from a reputable shop.

Most likley the instrument dimmer switch and that is part of the headlight switch, try wiggling it to get them on.

Fuse has blown in the heater control unit, I had this on my audi last year most likely cause, get youe user manual and loacte the fuse box.

never seen a deville so cant help,but it sounds like a relay is not being controled by the ECU and to locate this fault need special software and again to reset vehicle .sorry i couldnt tell you more know the fault but without dealer software ??i could only rewire to make it work