Saculia

iTrader: (1)

Hi guys, my car just started acting up after the weather got cold. My volts would seem to fall and my interior lights would dim. Voltage falls below 12 volts according to my volt meter inside the car. When I rev the engine up the volts will go up most of the time as expected and the lights will get brighter, but on occasions the volts will go down after a rev. I tried to recreate the problem by loading my electrical system with the accessories and measuring the voltage at the battery with my digital volt meter. To my surprise, when the voltmeter on my dash shows below 12 volts, and my interior lights seem dimmed, the voltage at the battery is 16 volts according to my digital volt meter. The head lights are also bright and don't dim. Also on a couple of occasions now my volt meter has jumped way past the 13 volt mark, almost to the red, but comes down after I rev the engine. I am clueless as to what is going on. What can be causing my volt meter to behave so erratically and my interior lights to dim, but the actual voltage at the battery is quite consistent? I tried shutting off the car and measuring voltage at the battery, and it was 14 volts. Upon starting the car the voltage goes up to 16 volts. So it seems that the alternator is charging. Is there a connection between the signal to my voltmeter and my interior wires? Could this be due to a faulty ground and where might that ground be? I am planning to take my car on a cross country trip to visit my family for the holidays, but am skeptical to do so without resolving these issues. Any help will be greatly appreciated. Thanks a lot in advance.

Corky

In my opinion, 16v is too high & with the engine shut off, your battery should be reading 12.3 - 12.5v. First off, I never trust the voltmeter on the dash. You were smart to verify your readings with a digital VOM. Without seeing the car I would suspect voltage regulator problems. But, first check all your connections to make sure they are tight and there is no corrosion on any wire end. Charging at 16v is not doing your battery any good. Normal charge should be in the 14.0 to 14.6v area.
Corky

Saculia

iTrader: (1)

Thanks a lot for the reply. That was what I suspected. I am going to pull that alternator off tomorrow and take it back to o'reilly's. The junk alternator came with a life time warranty, which means that I should be able to get it exchanged. I just hope that they can reproduce the problem since it is very intermittent and does not happen all the time. I don't want to risk the thing dieing on me on my trip 700 mile away from home.

Saculia

iTrader: (1)

Here is an update to the situation. I replaced the alternator and the problem got fixed for about 2-3K miles. Now I am getting the same symptoms again. Is this due to a poor quality of alternators, or could there be something in my car that is killing these voltage regulators. My car has underdrive pulleys, but it has run with them for years without problems, so don't quite see how that can be a problem. I am about to replace the alternator pig tail and see if that solves the problems. Maybe the old one is not making good contact. What do you guys think? Any help is greatly appreciated. This is the last think that I can think of doing before spending a bunch of money on a 140 amp alternator.

bigchief

Saculia, i've had pretty much the same problem as you, the thing is, its usually impossible to get answers to electrical problems from anyone.... the voltage in my dash sometimes reads 13, but usually reads 11-12... but my battery also reads the same as my dash, so in that way, our problem is different since you are describing your voltage at the battery and at the dash to be different.

I've changed my alterntor and my battery numerous times, so i really dont think that has to do with anything. I think it might actually be the cable that carries voltage from my battery to my starter, or my battery to my alternator. Also somewhere there might be a bad ground, but i would think that it would affect other things as well, and i would have noticed it by now.

Anyway, if i find the solution to my problem (which i've had for a few years now), i'll definitely let you know. The thing is, you say your interior lights are dimming.... that HAS to mean that you have inferior voltage, maybe your volt meter is wrong that you're using, i mean if your voltage was at 16, your interior lights would be bright as hell...... right?

Saculia

iTrader: (1)

When the interior lights are dimming, I am usually on the road, and can't read the voltage at the battery. I suspect that I have a wiring problem somewhere. The first thing that struck me was that there is an exposed wire at the alternator pigtail that I noticed. It is right up against the plug. I am going to replace the pigtail and try to check as many grounds as I can find.

NINÅ

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Saculia

iTrader: (1)

Well,
My alternator is guaranteed forever. It was the more expensive one from o'reilly's. The issue is that I don't want to have to deal with this again. Even if the alternator is guaranteed forever, it still takes my time to replace it. Not to mention that if it fails on the road, it can leave me stranded hundreds of miles away from home.

Jono4820

iTrader: (1)

Check ALL of the ground and power connections under the hood. Clean and lubricate with dielectric grease.

Saculia

iTrader: (1)

Here is an update.
Last night I checked all ground wires under the good, cleaned the battery cables, and replaced the alternator pigtail. I soldered the connections of the new pigtail and protected them with shrink tubing. The new pigtail I purchased had a third, black wire, which I grounded to the alternator bracket.
So far everything is working fine. My voltmeter on the dash is just past the 13 volt mark when I drive the car and drops slightly when I am idling at a traffic light. So far it seems like the problem is fixed. I hope it stays that way.
Thanks again for all your help and suggestions.