20 Most Recent 1998 Cadillac DeVille Questions & Answers

create your own earth wire off the original and screw/bolt to a good earth source.Nothing flash just a test if it works make a more permanant one

1998 Cadillac... | Answered on Nov 06, 2018

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 >


1998 Cadillac... | Answered on Feb 05, 2018

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.

1998 Cadillac... | Answered on Jan 12, 2018

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

ac heater programmer location-wg5qrgvg4vn31k55pcnhuwcx-1-0.jpg

1998 Cadillac... | Answered on Nov 19, 2017

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.

1998 Cadillac... | Answered on Sep 14, 2017

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.

1998 Cadillac... | Answered on Sep 08, 2017

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.

1998 Cadillac... | Answered on Aug 18, 2017

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

1998 Cadillac... | Answered on Jul 22, 2017

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!

1998 Cadillac... | Answered on May 10, 2017

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.

1998 Cadillac... | Answered on Apr 17, 2017

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.

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 .

1998 Cadillac... | Answered on Mar 30, 2017

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