1998 Cadillac DeVille - Answered Questions & Fixed issues

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 -------------------------------------------------------------------------------- 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.

In the fuse block

Question edited for full make and model. Question moved to sub category. There were 3 Recalls, and are listed here. https://www.nhtsa.gov/vehicle/1998/CADILLAC/DEVILLE/4%252520DR ..

A good guess. The resistor is a common failure item.

There's a good chance the alternator stopped working and needs to be replaced.

it's highly very unlikely that a bulbs are faulty here . The most likely cause is the fuses then and the headlight relay and also headlight switch and dimmer switch or a wiring fault. About the only cause that is a simple fix is blown fuses.You should get a mechanic to take a look at the car and see why some of the head lights work and some are not working.

Some fixya user told me a website reliable-store it is very good.. I used it to repair my shredder it had some spark issue which wasn't easily fixed. you can go there and try

I would check to see if there's anything loose back in the rear and area of your suspension but it definitely could be a badd Strut

On this website you find fuse box diagram and description for Cadillac DeVille (1997 and 1999). Maybe it helps you https://www.carknowledge.info/cadillac-deville-1997-fuse-box-diagram https://www.carknowledge.info/cadillac-deville-1999-fuse-box-diagram

These vehicles have very complex electronic's , your best bet , take it to a qualified repair shop. You do not have the knowledge or diagnostic tools to fix it . Hooking up a factory or professional type scan tool should be the first step in the diagnostic procedure . Then reading how these systems are suppose to work in the factory service repair manual . Not going at it blind an rigging it .Or are you this kind of person >

I would like to know more but my guess is something shorted get a cheap short light tester and a friend .Now disconnect the ground cable and clean the positive cable and put it back on.Now have your friend hold the tester to the battery post and the other end to the cable if it lights up you should pull one fuse at a time and find out what circuit the short is in.WARNING make sure the interior light is not on this will show a short or power drain.As far as the belt and motor mount ??? doesn't sound right.

Blower Motor Inoperative at Any Speed (Front) ? The heater & A/C programmer is probably the problem . The 4 to9 volts on white - that's not how you test that circuit . That is a PWM - pulse width modulation circuit . The programer switches that signal on an off real fast . You need a automotive lab scope to see the square wave that would be produced . HVAC Blower Motor Circuit

There is a check valve inside the fuel pressure regulator that can leak off the necessary fuel pressure to start the engine quickly. Have it tested or just replace it.

Keep checking the oil every time you gas up and you will be able to estimate how much oil it uses/100 miles or so. Then you can plan your trip. If the oil gets too low a warning will show up. That engine has about 7 quarts in the pan. As long as you don't run the engine low on oil the leak is just waste.

First, you must have a properly installed thermostat that is working correctly. Second, Northstar engines are notorious for air in the cooling system after draining and refilling - keep checking the purge tank level after overheating and after the cooling system cools down. Third, make sure your cooling fans are working correctly (relay, fuse, temperature sensor) - check to make sure both are running when it overheats. If all the above is correct, the problem will probably be blockage in the system (try a flush) or your water pump itself is failing.

run the fault codes indicates a wiring problem to the transmission ( loose harness connectors ) indicates a fault in the torque converter clutch solenoid / servo - again a faulty wiring connection

Most modern cooling systems are pressurized, the operating pressure is determined by the radiator cap. Check the pressure rating on your cap, and you can determine the boiling point of water. A 14 psi cap = 245 degrees F, at 16 psi = 250 degrees, etc. Coolant ("antifreeze") runs higher than that. Modern engines are more efficient at these higher temperatures, which is why they use a pressurized system. So if you're not getting any caution lights, and you cooling fan(s) are working, you're probably OK. But this also explains why you NEVER remove the radiator cap while the engine is at operating temperature - the reduction in pressure in the entire system means ALL the coolant is above its boiling point, and it WILL all try to get out at once!

Since the replacement is a different one from the one you are replacing, the car wiring harness is probably different from the one needed for the new radio. This is a really important difference if the new one is part of a Bose system and that is not the option installed in your car. The best way to check is for you to identify the option codes for each radio and go to alldatadiy.com and compare the wiring diagrams.

First off you need to know how these thing's work ,computer controlled . Trunk Release Function When the PZM receives a serial data message for the activation of the trunk release solenoid from the instrument cluster or from the RFA, the PZM energizes the trunk release relay under the following conditions: • The transmission is in PARK • The valet lockout switch is not activated. Components This vehicle has electronic components which the service technician controls in order to provide valuable self-diagnostic information. These components are part of an electrical network that controls various engine subsystems and various body subsystems. A description of each of these subsystems is in the appropriate subsection of this service manual. These major components that compromise the computer system monitor the system sensors and the system switches. These components are the following: • The powertrain control module (PCM) • The instrument cluster • The air controller module (ACM) • The sensing and diagnostic module (SDM) • The electronic brake and traction control module (EBTCM) • The continuously variable road sensing suspension module (CVRSS) • The body control module (PZM) • The integrated radio controller (IRC) • The remote function actuator (RFA) • The climate control panel (CCP) • The cellular telephone (PHN) System Functions The body control module (PZM) performs the following functions: • HVAC afterblow control • Battery guard • Door lock and unlock • Fuel level • Retained accessory power (RAP) • Theft deterrent • Exterior lighting control • Interior lighting control • Trunk release • Time of day for the radio display • Rear defogger • Fuel door release • Vehicle personalization For more information about these functions refer to the appropriate sections. Your probably have a lose connection somewhere , ground for the BCM or instrument cluster . Behind the dash or instrument cluster ! or other places . G-400 ,G205 The instrument cluster supplies the turn on signal for the alternator DTC B1910 Generator L-Terminal Open Circuit DTC B1911 Generator L-Terminal Problem DTC B1981 Battery Voltage Low The generator provides the voltage to operate the vehicle's electrical system and to charge the battery through CKT 1 (RED). When the ignition switch is placed in RUN, narrow width pulses on CKT 23 (GRY) are supplied by the powertrain control module (PCM) to the rotor, creating a weak magnetic field. When the engine is started, the regulator senses the generator rotation by detecting AC voltage at the stator through an internal wire. Once the engine is running, the regulator varies the field current by controlling the pulse width. This regulates the generator output voltage for proper battery charging and electrical system operation. The PCM turns on the VOLT indicator via Class 2 serial data line CKTs 1807 (PPL) whenever undervoltage, overvoltage, or a stopped generator is detected on CKT 225 (RED). When the ignition switch is placed in the RUN position, voltage is supplied to generator terminal L by the instrument cluster, turning on the regulator. The generator's voltage regulator controls current to the rotor, thereby controlling the output voltage. The rotor current is proportional to the electrical pulse width supplied by the regulator. When the engine is started, the regulator senses generator rotation by detecting AC voltage at the stator through an internal wire. Once the engine is running, the regulator varies the field current by controlling the pulse width. This operation regulates the generator output voltage for proper battery charging and electrical system operation. The generator F terminal is connected internally to the voltage regulator and externally to the PCM. The PCM monitors the field voltage on the generator F terminal. It's more then likely just a lose connection somewhere . Could take half your vehicle apart to find it . My first place to look would be here , G400 In the left rear of the passenger compartment, under the rear seat BCM ground .