: At my wits end

05-05-11, 08:17 PM
Hello all,

Please let me start by saying i am a new cadillac owner. She however has turned into a beast of burden. My baby is a deville 8-6-4 with a charging issue. i have gone thru 3 alternators and 2 batteries. All the fuseable links are intact, no shorts in the harness that i have been able to detect. i am not sure where to look next. is there a fuse somewhere besides the ones that are under the dash? she has 40,000 original miles but a little rough around the edges. the previous owner had a monster sound system and alarm installed. the alarm is still there but the sound system was taken out. i think the system overpowered the electrical components.
any help would be great. thank you:)

cadillac kevin
05-05-11, 08:31 PM
have you checked the parastatic drain fuse by fuse using a meter ? parastatic draw testing (http://flashoffroad.com/electrical/Batteries/BatteryDrain.html)
some things to check off the top of my head
pull the alarm fuse and see if the problem goes away
disconnect the aftermarket radio and se if the problem goes away.
some light might be stuck on with a burnt bulb (can cause a short)
check your factory grounds in the engine bay.

05-05-11, 08:38 PM
Is it not charging or is the battery dying after sitting for a while? Battery light on?

05-05-11, 10:06 PM
thanks for the reply. the sound system was removed before i purchased the car however i dont think it was removed properly. there was still power cables all over the place. a super heavy duty alternator was in place rated somewhere around 200 amps! i replaced just about every fuse there was. for whatever reason the alternator will not charge the battery. all the grounds are in place because i had to repair part of the engine harness due to a rat chewing it away for nest material. btw what is the standard output required for this engine. i have a 100 amp unit installed now. will try the draw test tomorrow. thanks again

cadillac kevin
05-05-11, 11:06 PM
100 amps is plenty. IIRC, depending on the year standard alternator output was about 100 amps . 120 amps was optional. as long as you have 90 something amps (which was the base alt for the caddys) you'll be fine, anything below that you start having issues under moderate loads. my caddy has a 78 amp "high output" unit from a station wagon. it works...sorta- as long as you don't drive at night with the radio and heat on at the same time. results in a pulsing light show.
if you havent already, I'd disconnect the aftermarket power cables for the stereo system (don't have to remove them, just disconnect them.)
a blown fuse wouldnt result in battery drain. It would just mean something was pulling too much power or a power surge occured or something was incorrectly grounded (shorted out).

is anything electrical in the car not working correctly?

05-05-11, 11:08 PM
There is not much to the charging system, the alt sends current that is controlled by a regulator. I would say to make sure the wires to the regulator are correct and, even if they are correct, test with a volt meter that they are producing the right numbers. Other than that, I'm stumped too. If its been like that since you repaired the wires, I would say that there is more repair that needs to be done. Maybe a repair came loose?

05-06-11, 12:09 AM
Does the "NO CHARGE" light, on the instrument panel, work. It's wired directly into the charge circuit and if the bulb is out, the alternator will not charge the battery.

05-06-11, 06:53 AM
Check the output of the alternator with a multi-meter. It is either putting out voltage or it isn't.

05-06-11, 06:17 PM
all the cables from the sound system have been removed from the car. i haven't seen a no charge light at all so i guess i need to open up the dash and look at that. all the other electronics work in the car, even the 8-6-4 system, the part of the harness i had to repair was for the connectors to the solenoids and to the tbi to trigger the 8-6-4. i will search for anymore open grounds and the no charge light and let yall know what i find. thanks for all the help everyone

05-06-11, 10:39 PM
I also have a V8-6-4 in my 1981 Coupe DeVille with charging issues as well. Turns out it was the PCM not going to sleep when the car was turned off. Garage had a hell of a time finding a new one.