Voltage gauge is reading low.

1988-V-6 2.8

When I first start the car, the voltage gauge reads between 13 -14+ Volts,
Then after the car is warmed up, voltage reading is around 11-12 volts, if I give it some gas
and accelerate, the reading drops to around 9-10 volts. Also, if I turn on the air conditioner
It will drop to around 9-10 volts.

Just double checking before I do the obvious??

Any feed back?
Thanks,
Michael

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[This message has been edited by 2000RagTop (edited 09-05-2004).]

have the charging system tested. Many places do that free.

after that start working the grounds and main power cables. see wire service in my cave.

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Do a quick look to see if the belt is on the alternator, it sounds like you're running on the battery.

JazzMan

quote Originally posted by JazzMan: Do a quick look to see if the belt is on the alternator, it sounds like you're running on the battery. JazzMan

I have checked the belt/tension already .....also, the connections are all good.

Do you have an actual volt meter, like a multimeter? Check the voltage at the battery and at the alternator output wire. Both should be within 1/10 volt of each other, and that should be around 14.5V with the engine running.

JazzMan

quote Originally posted by JazzMan: Do you have an actual volt meter, like a multimeter? Check the voltage at the battery and at the alternator output wire. Both should be within 1/10 volt of each other, and that should be around 14.5V with the engine running. JazzMan

When I pulled the connection on the alternator, I checked the "SFLP" plug, grounding the connection (larger red wire)to ground, with engine running, I was not getting any or little reading, (no output)!

Now, I'm assuming this is the right connection ? (red wire) on the "SFLP" plug

[This message has been edited by 2000RagTop (edited 09-05-2004).]

Your voltage gage on the dash should read about half way or slightly above half way.If you gage is too low,peged in the red zone, or bounces up and down wildly with the engine reving.Then you probubly have a bad voltage regulater or a bad diode.Take the whole car in and have it tested,if they say it's good have it tested at another store.

Pulling the side connector off the alternator makes it shut off and not turn on.

Again... Have the charging system tested. Autozone, National Tire and Battery, and many others will do that free. They can test for more than voltage problems.

quote Originally posted by theogre: Again... Have the charging system tested. Autozone, National Tire and Battery, and many others will do that free. They can test for more than voltage problems.

Had this done at three different places, All of them said the system was working/charging correct.
Also, had the battery checked, that was good also.

Maybe I have a bad/incorrect voltage gauge??

Get a multimeter and measure the actual voltage. The dash guage is not exactly known for being accurate.

JazzMan

quote Originally posted by JazzMan: Get a multimeter and measure the actual voltage. The dash guage is not exactly known for being accurate. JazzMan

I did this, showed right at 14.3 volts......I also had 3 different shops check the system...all said it was charging correct!
The thing that's making me scatch my head is when I give a little gas.....the voltage goes down on the gauge ??

check the water in the battery. you could be over heating the battery and throwing off the voltage regulator.

quote Originally posted by 2000RagTop: I did this, showed right at 14.3 volts......I also had 3 different shops check the system...all said it was charging correct! The thing that's making me scatch my head is when I give a little gas.....the voltage goes down on the gauge ??

Are you saying that the voltage on the guage goes down, but it remains ok on the meter?

JazzMan

quote Originally posted by JazzMan: Are you saying that the voltage on the guage goes down, but it remains ok on the meter? JazzMan

yes, when I rev the engine the multimeter remains the same, as did all the testing at the 3 different
shops......but the voltage is showing a drop on (cars) Aux voltage guage.

That's a strange one for sure. The dash voltmeter gets its voltage from the guages fuse, and that voltage is shared by the oil pressure guage. Does the displayed voltage vary with the oil pressure reading?

JazzMan

quote Originally posted by JazzMan: That's a strange one for sure. The dash voltmeter gets its voltage from the guages fuse, and that voltage is shared by the oil pressure guage. Does the displayed voltage vary with the oil pressure reading? JazzMan

Oil pressure reading appears to be fine....just the voltage side is acting strange.
I first noticed this when I would turn the air on, voltage would drop. I just thought it
was putting to much of a load on it. Now, the air doesn't have to be on to show a lower reading.

Again, when I rev the engine to around 2000. it drops on the aux gauge. but the voltage did not drop
on the testers at the 3 different shops. all show out-put to be right around 14.3 volts ??
I'm thinking I have a bad aux voltage gauge.