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1993 Cadillac Eldorado Sport Coupe 4.6L Northstar "Y"
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130 Posts
Discussion Starter · #1 ·
Hello im sort of new here but hoping i can get some answers to a very difficult issue im having. So i have noticed for a while now that all my interior lighting (radio, tach, even overhead lights) and my headlights have been doing this "flickering" or "pulsating". I noticed that i was starting to see the issue become more severe and noticable as time went on. Coming back to the Central office for my workplace to return home, i tried starting my car.... but would not start. It was actually very bizarre, all lights (headlights, interior, even radio) was working properly with car shut off with just "accessories" enabled. I feared the worst (STARTER! N*), but i know sometimes even if a battery seems fine, sometimes its just not giving out enough juice to start the engine, but just enough to work your accessories such as lights and radio. Least to say, i requested a "jump" from a co-worker just to see, and behold, it started!

I immediately at that point walked into autozone that evening and purchased a duralast "gold" battery and installed it in the parking lot with other thoughts that that may be the culprit for my lighting issue as well. Installed the battery and have not had issues starting since then. Now im stuck troubleshooting this electronics issue though. I walked back into autozone and had them test the alternator with a voltage detector, and readings were ok, but just to be sure i disconnected the alternator and bench tested, and everything came out ok. So now i purchased a new alternator "just in case" figuring i would eliminate the "expensive" voltage parts first to eliminate any potential that those parts would be any involvement in this issue which it was not.

So now im stuck with "pulsating" lights (interior/exterior) and its a tad bit embarrassing, and even though its not very common this happens with any vehicle that ive ever owned, im starting to think it is the Voltage Regulator. I have already purchased a ground cable for the battery just because the ground termination on the vehicle seems a little corroded and almost rusting through to the point it potentially is not even providing good ground, i tested with the ground meters we use at work to see the dB, but our meter clamps dont work so well and im testing 6gauge cable rather than telephone grounds so im not really trusting anything on our clamp for a battery ground. Nevertheless i am going to install a new ground cable anyways to eliminate that potential issue.

I also try pulling up codes too but all i get is "AC/Condenser" codes. (and those codes are right off the dash, not off of autozone/murrays/napa/etc.)

Please help, i want to install a new head unit and speakers soon but dont want to unless this issue is repaired. I have already had a headlight bulb blow out, but i cannot confirm whether this issue im having poses relation to the headlight or not.

Thank you,
Josh
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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73,045 Posts
You have voltage regulator problems and/or problems with the alternator wiring harness or connector.

You should see a voltage of 12.4 to 12.6 in the DIC just before key:START, then after START, voltage ramping up to about 14.6 as the battery charges. At full charge and regulator shift to float mode the charge amperage ramps down to that required to run the loads in the car while voltage stays at 14.4 to 14.6. Some Northstar installations see a running voltage of 14.8.
 

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1993 Cadillac Eldorado Sport Coupe 4.6L Northstar "Y"
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130 Posts
Discussion Starter · #3 ·
You should see a voltage of 12.4 to 12.6 in the DIC just before key:START, then after START, voltage ramping up to about 14.6 as the battery charges. At full charge and regulator shift to float mode the charge amperage ramps down to that required to run the loads in the car while voltage stays at 14.4 to 14.6. Some Northstar installations see a running voltage of 14.8.
Before Keystart i get around 12.4-12.6. When started it does ramp up to about 14.5-14.6. But after a while (mabye 30sec-1min) it will go down to about 13.8! I Like i said my alternator is new, my battery is new... sometime this week i will be replacing the battery ground, then checking all power connections between battery/alternator and make sure there good. If thats not it... would you suggest the Regulator would be the culprit? :hmm:
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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A steady DIC voltage of 13.8 is not really that low, on the scale of things. 13.8 is plenty of voltage to 'float' the battery and still run all the necessary car loads - the "smart" chargers in marine applications use exactly that voltage (13.8) as a normal full-battery running figure, but our cars traditionally stay in the low-mid 14's. That has to be an automotive regulator design. The bugaboo is why does your present regulator "pulsate" and deliver a varying voltage (which is what you're describing) under running conditions? It's either the regulator itself (your new alternator = new regulator....) or a bad field or excitation voltage signal input. My guess is either a wiring fault or high resistance connection.
 

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1993 Cadillac Eldorado Sport Coupe 4.6L Northstar "Y"
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130 Posts
Discussion Starter · #5 ·
... My guess is either a wiring fault or high resistance connection.
So should i stick with checking bonding/grounding with wiring this weekend when planned? I plan to add a new ground cable because the existing ground looks really "shotty" thats terminated on the body. Thinking about bringing it to a cleaner area like the fender? I will also be replacing the terminal bolts as well because there pretty nasty.. I will eyeball the battery cables themselves too to see if those arent bad either. Will post by Sunday about the grounding
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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ANY ground cable should be bolted to the heaviest panel on the unibody/frame as possible. IF a fender is bolted on, that's not a good ground - paint, washers, plastic, etc.

I always try to have the engine-to-body ground cable "battery cable sized".
 

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1993 Cadillac Eldorado Sport Coupe 4.6L Northstar "Y"
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130 Posts
Discussion Starter · #8 ·
Ok so i took a drive and here's what i got

11.9-12.2V right before start (with only accessories on)
14.0-14.3V while running/driving

Do these numbers sound in the same ball park?

Interior lights and headlights still seem to pulse/flicker while idling the most, when accelerating, it seems the problem goes away until idling again? :hmm:
 

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'98 STS (RIP @ 206,xxx miles)
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Ok so i took a drive and here's what i got

11.9-12.2V right before start (with only accessories on)
14.0-14.3V while running/driving

Do these numbers sound in the same ball park?
Those DC voltage numbers are in the "acceptable" ball park. It matters very little (to me) what the battery voltage is "before start" IF your battery will crank and start the engine each and every time you ask the battery to do that.

Interior lights and headlights still seem to pulse/flicker while idling the most, when accelerating, it seems the problem goes away until idling again? :hmm:
With the engine at idle, read the AC voltage at some convenient point in the system (battery terminals will work). You will need a handheld multimeter of some kind set to read AC VOLTS.

AC voltage measured should not exceed 90 mV at 1,500 RPM under a load. The load would be headlights and HVAC fan and rear window defrost.

Another way to state 90mV is 0.090 V.
 

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1993 Cadillac Eldorado Sport Coupe 4.6L Northstar "Y"
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130 Posts
Discussion Starter · #10 ·
Those DC voltage numbers are in the "acceptable" ball park. It matters very little (to me) what the battery voltage is "before start" IF your battery will crank and start the engine each and every time you ask the battery to do that.


With the engine at idle, read the AC voltage at some convenient point in the system (battery terminals will work). You will need a handheld multimeter of some kind set to read AC VOLTS.

AC voltage measured should not exceed 90 mV at 1,500 RPM under a load. The load would be headlights and HVAC fan and rear window defrost.

Another way to state 90mV is 0.090 V.
I will also try this as soon as i can! :yup:
 

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1993 Cadillac Eldorado Sport Coupe 4.6L Northstar "Y"
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130 Posts
Discussion Starter · #11 ·
Just got a code recently, Keep Alive Memory (KAM) Reset/PCM has lost primary battery power P109 i believe? mabye battery is getting disconnected (or almost) whether driving, idle, parked... idk... or this could have a relation to me recently replacing the battery... who knows
 

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1993 Cadillac Eldorado Sport Coupe 4.6L Northstar "Y"
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130 Posts
Discussion Starter · #12 ·
Ok so this is what I did today:
Swapped battery terminals with new
Added ground to frame from battery
Checked all fuses (which all were ok)

I'm now starting to think it may be a relay? Anyone hav suggestions on that?:confused:
 

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1993 Cadillac Eldorado Sport Coupe 4.6L Northstar "Y"
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130 Posts
Discussion Starter · #14 ·
And the AC Voltage reading is ??
I apologize and have not been able to get around to getting that task done. I will be sure to get that tested and results posted by tomorrow or monday :thumbsup:
 

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1993 Cadillac Eldorado Sport Coupe 4.6L Northstar "Y"
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130 Posts
Discussion Starter · #15 ·
Saw this on another guy's forum!

Re: 93 eldo lights flickering ... this sucks

My 88 did this before the light finally quit working for good. The dash lights, gauges, heater and airconditioner all quit at once. Had to replace the central power supply box under the dash near gas pedal.
Does anyone think this could possibly be my issue? I want to know before i start swapping relay's for no reason. :suspect:

Also, the AC results came out to 80-85mv or 0.080-0.085 with rear defroster, at 1500rpm
 

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93 eldorado
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yeah im the guy whos thread you got that from. my 93 is doing the same thing. im having it checked by an auto electronics shop. its expensive but hopefully they can find out what the deal is cause im painting it and doing some other things, so it would be useless if the lights dont work right. anyway, i will post whatever they find the problem to be.
 

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1993 Cadillac Eldorado Sport Coupe 4.6L Northstar "Y"
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130 Posts
Discussion Starter · #17 ·
It has come to the end of the month. If this issue was indeed my alternator (in my experiences) i would have had a dead battery by now. I am starting to think this issue is in result of the battery cables themselves, but now i am starting to have a rough idle issue. Feels like its misfiring.

I have commented and reviewed other posts about misfiring and the whole thing is a non issue, i will replace wires, plugs, coils. My question is though, Is or can this misfire issue bother with my idle lighting issue? I used to drive a 98 Eddie Bauer Ford Expedition and i remember when an ignition coil died, i would have headlight issues. I want to know if this goes hand in hand with cadillac as far as relation between misfires and accessories issues. Considering both are an "electrical" issue.

I hope to get this lighting issue fixed before i do my project in March (or whenever we start getting good dry 50-60 degree weather).
 

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1999 Eldorado 2000 Jeep TJ 2000 Ford SD 4X4 Diesel crew cab
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For what it is worth My 1999 Eldorado did the flickering thing as well when I first bought the car I drove it for over 2 months before I went through and replaced a bunch of items due to preventative Maintenance reasons that included starter, water pump alternator hoses plugs belts idler pullys A/C compressor ECT once I completed these repairs the flicker was gone it could be in the alternator I would stay with OEM parts here do not get a cheap parts store rebuild.
 

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1993 Cadillac Eldorado Sport Coupe 4.6L Northstar "Y"
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Discussion Starter · #19 ·
For what it is worth My 1999 Eldorado did the flickering thing as well when I first bought the car I drove it for over 2 months before I went through and replaced a bunch of items due to preventative Maintenance reasons that included starter, water pump alternator hoses plugs belts idler pullys A/C compressor ECT once I completed these repairs the flicker was gone it could be in the alternator I would stay with OEM parts here do not get a cheap parts store rebuild.
Def. not doing a ghetto rebuild. I am starting to think its the voltage regulator though, which will need removal of alt. to actually replace... honestly the regulator(70-80$)? or a new alt. w/regulator all together(100-120$)?
 

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1993 Cadillac Eldorado Sport Coupe 4.6L Northstar "Y"
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Discussion Starter · #20 ·
Ok. Final verdict? Alternator! last night i picked up some friends because they were too intoxicated to drive and i am against drunk driving. I received a "no battery charge" warning followed by "low voltage" soon after... least to say, my car is sitting in a petsmart parking lot right now as we speak. Had family come out at 5:30am this morning to give me a jump and charge the battery fully so i can at least make it home to swap the alternator out. The damned thing wouldnt hold a charge if it was the apocalypse! It became possessed and dash functions were going on the fritz! Hard to believe when EVERYTHING tested good between battery and alternator, now randomly this happens on the way home when everything was working fine. We can erase this one off the chalk board and write this one up as solved to the alternator being the culprit, thank you all for your help. I should have known better, its just a shame i had to find out this way. now off to napa....
 
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