I posted this hear and on the electronics boards because I need help fast.

On Sunday I replaced my alternator with a Duralast 105 amp. (guy at AutoZone said it needed, stupid me). I took the battery home and tried charging it. The next morning after charging it is still completly dead. I went to Sears and bought a Diehard Gold battery. This morning the car drove completly fine. But tonight it died when I was shopping. After towing it home, I started charging again. An hour later there is enough juice to start the car, run the lights and everything that uses power. But the guage on my dash says it is still losing power. When the car was started it was near 11, by the time I moved the car in my driveway it was down to around 9.
My dads recomends tomorrow I take my car and excahange the alternator for a new one. What could be the cause of this and what should I do? Any help would be GREATLY appreciated.

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Mike Kenny
Current: 1991 RS 305 TBI
Past: 1990 RS 305 TBI (A woman forgot what red lights are for)
Current: mostly stock - newer 305 w/ 12,000 on it
Eclipse speakers all around w/ 10" tube powered by a Alpine V12 in back
K&N filter w/XStream flow lid - It is sweet!!
Future: 2" Cowl hood

 

Does the "Choke" light come on when you turn the key on before you start it??

If not, change the bulb. That's also the Alt light. Without it, the alt never "knows" that the ignition is on.

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"So many Mustangs, so little time..."
ICON Motorsports

 

First you may want to take the alt back to autozone and have it tested. You should check the continuity on the connection between your alternator and battery. Your car should be at 13.5-14 volts when running.
Also take the wiring harness plug out of the alt and see if you have +12v on all the terminals with the engine running.

 

What is the choke light? The only light s that came on was the one saying to check my air bag (INFL REST)

 

I don't think you would have a choke.

Your alternator isn't working.
assuming it is not broken then,
it is either not getting the signal to tell it to energize and start charging (small wires to plug).
or it is not connected to the battery positive terminal (large red wire on post).

I think autozone will test your alternator and battery for free.

 

If the battery and alternator check out okay, then look for a short circuit somewhere in the car that is drawing current. To see if you have any power drain with the key off, you can use a multimeter. Set it to "amps" (needs to be able to handle something like 10+) and disconnect the positive battery cable. Hold the negative probe on the + post and the positive probe on the end of the battery cable. The multimeter should tell you if there's any current flowing.

WARNING WARNING!!!!!

Get someone else to double check me on that proceedure, I'm not 100% sure I got it exactly right. Ask on the electronics board, or ask a tech that you know.

 

UPDATE:
I just got back from AutoZone and the battery tested out fine. The alternator was giving out results of -11 amps. I am going to test all of the grounds in my car and if that does not work take off the alternator and bring it back to get it tested seperatly. Anything else I should do or check?

 

get your alternator load tested at autozone. Make sure it produces 14 volts also.

to test for short.
turn off everything electrical in car (domelight, alarm, hoodlight, etc)

remove ground cable from battery.
connect test light between ground cable and negative post on battery. If light comes on then you have a short.

 

I had somewhat the same problem about 9 months ago. I replaced BOTH the alternator and battery with AC/Delco ones and the car runs great and even powers my new stereo equipment!

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End

Current Mods: LT4 Hot Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

7.5" 10 Bolt with 3.42s soon to come!

 

I attempted to test my connections. I am not 100% sure how to do it, so directions would be very helpful. Yesterday the car cranked over. Today it will crank over, but yet it gives out enough power to power lights w/o dimming like it was before. I am going to replace my starter because I am out of ideas. If this does not work I am towing it tow my mechanic.

 

Tonight I replaced my starter and still nothing. It turns and makes a clicking sound but does not start. I have enough power in the battery to use the lights, stereo, alarm etc... Can anyone please tell me how to test the wires in my car to see if they are drawing power (i.e bad grounds, stuff drawing power when off, etc...)? Thank you.

[This message has been edited by Neo (edited February 23, 2001).]

 

Have you checked your coil? If that isn't working properly, you have no spark. No spark=cranking but no vroom. Happened to me when my starter went out once.

 

Thank you for the suggestion. But HOW do I check these things. I mean I can pull it apart but what exactly will it look like if it is good/bad?

 

Checking for a draw is pretty easy. Put an ammeter between the battery terminal and the cable, and check the reading. If you have a draw, pull a fuse and recheck the reading. If no draw replace fuse. Repeat until the draw goes away. Whatever fuse you pulled includes the circuit that's pulling power. Make sure to take the measurement with all accesories off and the doors closed so the dome light isn't on.

Double check all the connections on your alternator, and have it tested. It really sounds like that's the problem. A draw would slowly drain the battery, but it shouldn't matter when the car is running. After all the alternator is designed to feed alot of current draw on a regular basis.