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1999 DeVille Concours
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Discussion Starter #1
Car Stats: 1999 DeVille Concours 4.6 Liter

Car History: Previously father's car, he stated but is not sure when these issues came about (time frame).
  1. A/C does NOT blow cold air but does blow tepid air.
  2. Radio does NOT work. No lights. No Sound. (Speakers do "thump" when disconnecting/re-connecting battery terminal)
  3. Power drain, battery goes flat within a couple of minutes.
Work that I have completed:
  1. Recharged battery.
  2. Measured Ampere draw from battery around top peak at 4.8mA
  3. Connected battery terminals and pulled one fuse at a time and checked draw at each fuse locations on terminal block in engine compartment
    (NO issues found at terminal block in engine compartment)
  4. Disconnected Negative terminal at battery and measured mA draw between Negative and Positive terminals
    a) Pulled Radio/Phone Fuse from terminal block in trunk, found draw to be at around 0.02mA
    b) Disconnected Radio harness from back of radio, thinking radio was defective and was draining battery
    c) Re-installed Radio/Phone Fuse (this fuse also allows electric windows and door locks to operate)
    d) Battery held charge longer....couple hours.
    e) Disconnected Radio Power Ampilfier. (No longer hear speaker "thumping")
    f) Also removed - reinstalled Comfort Fuse during ampere draw testing.
  5. Battery Drain issue seemed to have disappeared, drove from San Jose CA to Las Vegas NV (about 600miles) and had stopped a couple of times turning ignition off and on during travel. Upon parking car for the night and turning ignition off, heard clicking noise from behind dash, passenger side. Noise stopped after a couple of minutes. Parked cadillac overnight.

    Next morning opened driver side door by unlocking door with key. Inserted key into ingition and tried to start engine. When ignition got to "start" position horn beeped. Turned key off, tried again with same results. (Think it maybe secuirity alarm). Also the lights on instrument panel and digital readouts were delayed in turning on. Climate control readouts stay on for a short period of time then disappear and are replaced with double dash where temperature readings would be. At this point found that the clicking noise heard from previous night during shutdown was the fan blower behind glovebox.

    a) Removed Comfort Fuse - Eliminated Horn Alarm during startup
    b) Removed Amplifier Fuse - just in case
    c) Removed Radio/Phone Fuse - just in case
  1. Issue of none operation of radio
  2. Issue of no A/C
  3. Alarm (Horn) sound when starting engine
  4. No automatic door locks and window operation (due to removed fuse)
  5. Delay of instrument dash data
  6. No climate controls
Battery is HOLDING charge at this point and starts with no issues other than what is listed above

My question to you all is; (Thank You All in advance for any solutions)
1) Has anyone experienced any of these same issues?
2) Any known solutions to the above issues?
3) Could these issues be due to a defective module?

AC-Heater Programmer Module
(BCM) Body Control Module
(ESC) Electronic Stability Control Module
Radio Amplifier

98 DeVille, 97 DeVille d'Elegance
7,345 Posts
These are extremely picky about grounds. They use grounds to turn stuff on and off not the hots. I would start cleaning grounds. Main is frt engine by battery, there are 2 more on rad support that side and one or two more other rad support side. Other locations to clean(not all listed). Bothe kick panels, under and behind rear seat.
Also use the sticky to pull codes and list them here with current /history and definitions. There are links to code definitions also.

98 DeVille, 97 DeVille d'Elegance
7,345 Posts
Well the hvac control box is behind glove box. If you have dashes on hvac controls it is a loss of data, could be any number of issues. the fsm has a flow chart for testing. I would disconnect and reconnect the box. The grounds for it are kick panel passenger side. All your symptoms sure do look like a bad ground somwhere but who knows. Did you pull any codes yet?
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