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Voltage running consistently high, 15.1v?

19K views 9 replies 6 participants last post by  98Park 
#1 ·
My 04 LeSabre has developed this issue of running at extremely high voltages. I've only had the car 2.5 weeks, so this is frustrating.
The dealer had a new battery put in before I bought it. Now, running down the highway at 65mph, the DIC reads out 15.1 volts, sometimes down to 14.8. The lowest I've seen on the car in the past 3 days has been 14.4. Never gone below that, even with a major voltage drop (heated seat on, and two power windows going at the same time).
My dash lights are all burning out, one by one. I've lost all the backlights in the HVAC, half the lights in the wheel controls, 1/3 of the lights in the radio, and both seat heater switches.
I would normally assume a bad battery, but it is (supposedly) new, and I have not had any starting issues, even running a bunch of accessories with the engine off for 30 minutes or more. It doesn't even hesitate to start.

Would this mean the alternator is going? Is he voltage regulated in the alternator or is it PCM controlled?
The dealer has taken the attitude with me that "Its a used car, its going to have some issues, its not perfect..", so I'm kinda screwed here.
Any help or ideas or test to do? Ive already pulled the dimmer switch down in hopes that it saves the death of the rest of my interior lights. I have a service manual on order, but it hasn't arrived yet, so I am at a loss as where to start here..
 
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#2 ·
my prix runs anywere from 15-16v
 
#3 ·
Holy crap!
But that isn't normal, for the 3800s is it? Thats not normal for anything automotive electrical. I spent quite a bit of time doing stereo installs and custom wiring. Normal voltage should be somewhere in the 13.6 range, 14.4 would be a high if the battery was severely discharged, and the alternator was trying to recharge it and power the other electricals on the car at the same time. 15.1 just sounds like overkill, unless you're running a booster for the fuel pump or ignition? I know for my 87 3.8L turbo, you can buy a volt booster but it is only active at certain points above 80% throttle position. You don't want a car's electrics running at that high a voltage constantly?

I also looked at ZZP's "free mod" about the alternator wiring to raise voltage. Is it possible that terminal on my alternator is corroded or not feeding back properly, so it is in constant overcharge?
I wouldn't be so concerned, but all my dash lights are burning out. At this rate I wont have any lights at all in another week or so. I suspect the high voltage is whats burning them out.
 
#4 ·
i realy dont know wat average is. prob like 13.5-14.5. mines high cuz i got the alt rewire kit and volt booster
 
#5 ·
Check with a real volt meter and confirm. Stock gauges are notorious for being inaccuate.
 
#6 ·
I have checked the DIC reading with my voltmeter. It is nearly dead nuts on.

Being close to my old 3.8 LC2, I tried a few things.
I unplugged the 3 pin connector going to the alternator, and started it. It went quickly down to 12.0ish, and stayed there. Then the DIC warned me to check the charging system.
I set there with the car off, but with radio running, and it showed a pretty close 12.0-11.8 volts.
I sprayed some contact cleaner on the alternator contacts and in the connector, sprayed down the bat cable going to the alt, as well as the connection at the fuse box (the LeSabre has a remote terminal, as the battery is under the back seat).
Started it up, and it is now reading a more reasonable 14.6-14.8. Dropping to 14.2 ish when using power accessories.
So, it may just be some bad connections, but I'll have to take it out on the road and see if it has more issues with voltage fluctuations.
I haven't undone any battery connections, since the car has a theftlock radio, and even following Haynes instructions to disarm it, I can't get it to disarm. If I can figure that out, I'll take the battery connections apart and clean them up really good and see if that does it.
 
#7 ·
I had a bad regulator in a CS130 once on my 3800, it soared voltage to 17+. I had to replace....
 
#8 ·
My Voltage runs 15.2V consistantly

I have been searching for an exact photo or drawing of the connector which connects the radio to the system bus for factory radio control. I would like to know the pin outs on the connector itself. I saw this problem about the high voltage burning out the builbs. I have a lot of burned out bulbs and am not sure how to replace them. I still want to install my aftermarket stereo in my car as well...
 
#9 ·
My system pins my 18v gauge almost all the time, no burned out lights, and the only issue is my HID system goes into auto protect mode :(

My pioneer radio really loves the voltage tho.... boom boom without subs...
 
#10 ·
Sounds like the voltage regulator could be fishy, corrosion at the connector messing with the diodes maybe?
 
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