I have an 87 camaro that has dummy lights in the instrument panel and my battery light just came on. I replaced my battery just a few months ago and I know my alternator is working because I can restart my car after I drove it. Could this just be the sensor for the battery light is bad, if not, what is?

 

This is usually one of two things.
1) The alternator is not giving out the required charge (check for roughly 14V at the battery with engine running, or

2) The internal regulator pack in the rear of the alternator is bad.

Both faults require an alternator stripdown. Dead easy to do. Last time mine did this I replaced the regulator/diode assembly. Although these alternators are rare in the UK. You guys would probably replace the alternator completely.

Hope this helps.

Andy.

PS Check connections are clean and secure to the alternator before condeming anything.

 

i have to travel 581 miles in a couple of hours with the car, because i am visiting someone, would it survive the trip back...thats my concern...

 

As long as there is a good 14 ish volts at the battery, you should have no problems. Check it with headlights on.
The thing with these warning lights is that the alternator can be dead but the light will stay off, and vice versa! It is only a guide to the operation.
Check it and drive it! Then fix or repair it!

Andy.

 

how do you check it with the headlights and when i went to check the connections again to my battery, the positive and negative were a little loose, i moved the positive and the car died...could that be the problem all in all or is it still the alternator and if so how do you test it with the headlights...thanks again andy.

 

if the car is STARTED

and you remove a battery cable, the car should still run (the battery is only there to START the car. the alternator runs the car the rest of the time & recharges battery)

if you remove the cable, and the car dies, then the alternator is bad
get it replaced. (take the old one back, and you give it to the auto place, and they take money off of the cost of the new alternator)

just make sure they have the one instock that you need, or else (MOST LIKELY) you will have to wait a day or two for them to order it.

 

i tighten the the connections to the battery, they needed it but it didn't make the light go off...driving it could make the light go off now that there is a better connection? And i checked the headlights...i turned them on and i hit the gas and they stayed strong...is that the test?

 

if that is the case...would it be able to make a long trip?

 

if the alternator won't charge the battery, then it'd probably only last an hour.. 2 at the most.... i doubt you'd want to chance it.

 

DO NOT remove a battery cable with the engine running. This will fry the alternator big style! If it wasn't bad before, it will be then!!

Get a voltmeter. Get engine running. Switch headlights on. Check voltage across battery terminals. If it is around 14V you have no problems.

Andy.

 

i've never heard of anything like that, andy.

 

Andy is right, never remove the battery with the car running. In theory the diode trio(or rectifier pack on some alts) supplies voltage to the field of the alt to keep it excited regardless of whether the battery is on or off however NO manufacturer suggests doing this because of the resultant voltage spikes that can be generated, causing failure of the regulator IC in the alt or damage to the ECM or other sensitive electronics in the vehicle. The bulb or guage is wired in series with the sense wire, or sometimes ignition feed wire to the alt depending on the application. Does the bulb change intensity with engine rpm? You can have a situation where alt output is simply low causing the bulb to illuminate and then change intensity as the engine is revved. 9 out of 10 times when this happens the alt is on it's way out and in most cases suspect worn brushes. I rebuild quite a few for friends including my own and most times the rectifer pack and regulator IC is NOT at fault, it's simply worn out brushes or bad bearings. As was stated the best test is to go the rear post on the alt and measure from there to a good chassis ground. With a properly working alt you should measure anywhere from 13.5 to 15 volts. Anything less than 13 volts suspect the alt. Another thing to keep in mind when testing the alt without a battery is that the alt will have a high AC output, the battery acts much like a filter capacitor in a power supply smoothing out the output of the alt to a nice flat DC voltage which is what everything in the vehicle wants for proper operation.