Since I puchased my 88 Camaro, the voltage reading on my dash has been at a about 13.5 volts. Recently, I noticed that the voltage reading was getting lower and lower until the battery died.

I removed that battery and alternator and brought them to an Advanced Auto store. The alternator bench tested ok but they said the 4 year old battery was no good. Regardless of what the store told me, I bought and installed a new battery and alternator. The voltage read about 12 volts which was lower than expected. I removed the new alternator and installed the old alternator. The voltage was still around 12 volts was was lower than expected. I drove the car a bit for one day and it sat in the garage for the following 4 days. I drove the car on the 5th day and new battery was dead by that evening. Any ideas what might be causing the low voltage reading and the battery to eventually die?

 

make sure everything is off. maybe your trunk light or something stupid like that is drawing the power. and check if your wiring is bad

 

I had a very small draw on the battery, couldn't find a short anywhere, I placed a test light between positive lead and positive post, the light lite up...hmmm so I pulled each fuse, light didn't go out....checked the wiring for any breaks couldn't find anything...

Took the Alt. down and had it bench tested, showed good...hooked up all the wires and bam the test light was out, as soon as I touched the alt to the mounts the light lite up, conclusion the dioeds were shot, put in a new alt, had one sitting on the bench, no more short..

just a thought to check , I know the bench test only checks for charge, not internal shorts. ps the rebuld kit is only like 20 bucks through autozone.

Ken

 

I had a trunk light drain my battery. But that only took a few hours for my alarm to not even be able to chirp. But my hatch motor recently stopped working and thats why the light was on. Never noticed it because I always had the trunk cover pulled.

 

The old alternator has been replaced with a new one. The voltage has remained steady at 12 volts (which still seems low). We'll see how things go from here...

 

C'mon guys, seriously, it's obvious that both alt's are not charging and that both batteries are (were) ok, so the problem must be in the wiring!
12V means that the battery is on it's own, not being charged. You need at least 13.5V to ensure charging is taking place.
Use a test lamp on the positive post of the alt. (engine off) to see if the fusible link in the wiring to the battery is ok.

 

Make sure that the alternator is getting the 12 volt reference signal it requires.

 

Yes. Make sure the brown wire on the 2-wire plug in the alternator has 12V when the ign key is turned 'on', and also while the engine is running. If theres no power on that wire, it will not charge. Do you use your tilt steering much?

 

In response to FullSizeWagon - I disconnected the cable that was bolted to the alternator and checked for continuity with an ohm meter from the end of the cable to the other end and it measured 0 ohms which I thought indicated the cable was fine. Regarding your suggestion: Use a test lamp on the positive post of the alt. (engine off) to see if the fusible link in the wiring to the battery is ok. I'm not clear on what the difference using a test lamp will make but if the fusible link was blown, wouldn't the wire have an open in it and the resistance be infinite (the needle on the ohm meter would't move)?
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ToeHead - I'll check the brown wire. Any idea where the other end connects to? I don't really use the tilt much - why do you ask?

 

I think it actually runs through the "charge" light circuit in the dash. In any case, the alternator needs 12 volts at that wire or the regulator won't work and the alt wont charge.

 

I suggested using a test lamp simply because it has usually been a more common item in the toolbox, plus it's quick & easy to use, no need to disconnect. But your measurement indicates that the wiring & fuselink are ok, although it's hard to distinguish a poor connection (0.1 Ohm) from a real good one (0.001 Ohm). You'd have to use a voltmeter with engine running to check that. Next step is to verify if the brown wire has voltage (with key on) like Toehead says, using a voltmeter (or a test lamp).

 

Tested the brown wire - no voltage. I checked the fuse box and the 20 amp fuse in the F/P-FAN-C/H slot was blown. I replaced the fuse and all is good! can any one enlighten me as to what F/P-FAN-C/H means?

Thanks for everyone's help on this problem!

 

Congrat's!

F/P = Fan Pressure Switch (guess it turns on fan with high A/C pressure)
FAN = Coolant Fan (controlled by ECM)
C/H = Choke Heater Relay (this circuit also supplies the alternator)

There seems to be some discrepancy in the labeling as a TBI doesn't have a choke..
Anyway, your coolant fan would never have been running with this fuse blown..

 

Fullsizewagon - you are correct, I was aware the radiator fan was not running either (I didn't mention that problem because I thought it was unrelated)!

New rule: CHECK THE FUSES FIRST!

On to the next problem - ABS light is on in the 95 Buick after replacing the blower motor relay. I wonder if that is caused by a blown relay?!

Thanks for your help

 

Just when I thought that all was fixed. The 20 amp fuse in the F/P-FAN-C/H slot keeps blowing! The battery voltage was where it should be and the coolant fan was running. I drove the car about 100 yards and the voltage suddenly dropped and the fan stopped working. I checked the fuse and it was blown. What's going on? Possible blown Coolant fan relay? A short somewhere in the wiring? Blown Fusible link? Any suggestions?

 

If it will work again when you replace the fuse, it must be a short in the wiring somewhere.

 

I have replaced the fuse several times and the fuse blows as soon as I start the car.