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Forthewines 07-01-2013 09:53 AM

Problems Starting after a Alternator Replacement
Here goes. I replaced my alternator yesterday. After i got everything back together I started the car (with help from a jump pack) and the car ran fine. I let it run for a bit to let the battery charge back up. I then turned off and on and everything seemed to work as usual. Later that night I started the car it fired right up went to turn the headlights on and it died. now with the key off the security light blinks when I turn to the on position I only see the oil light dimmly lit. When I turn to crank it absolutly nothing happens. The battery was reading 12.6V. Electrical is not my forte. Fuses are straight forward but How do you know if a relay is fried?

Milton 07-01-2013 10:03 AM

Start by checking connections and wires.

Examine all wires and connections at the alternator. Is everything bright, shinny, free of corrosion/dirt/rust? Are all connections tight? Examine the other ends of those wires in the same manner.

Examine all wires and connections at the battery in the same manner. Examine the other ends of these wires in the same manner.

Good luck!!

Forthewines 07-01-2013 11:25 AM

Checked the connections (all good) and It started like it usually does. I turned the headlight switch and it died. I tried again and it started back up. Tried the headlight switch again and it stayed running. Then I turned everything in the car on and were still good. I still don't trust this thing. I'm going to go out and test it every once and awhile tonight. Something doesn't feel right.

SilverST05 07-01-2013 12:56 PM

You need to make sure the battery is fully charged when you replace an alternator. If it isn't the alternator can get overworked by trying to maintain vehicle and charge the battery at the same time. You can kill an alternator. Doesn't happen every time. But it can. I work at O'Reilly Auto Parts, I see it enough. Often times when either a battery or alternator go out the other follows from trying to make up for the other one going bad.
And just cause the battery reads 12.6 volts doesn't mean it has the Cold Cranking Amps to turn an engine over. You need to test it with a load tester to be sure.

Milton 07-01-2013 02:22 PM

Next step is to pull the battery, take it to your local AutoZone/O'reilly/etc and have it tested. Do not remove the battery with the engine running! If it tests good ask to have it fully charged, if bad than buy a new battery and ask to have it fully charged.

Now that you have a known working, fully charged battery install it.

Check the belt that drives the alternator, is it appropriately tight? We want to make sure the alternator is turning.

Start the engine and with everything electrical off, measure the voltage at the battery with the engine at 1,500 rpm.

Next turn on all lights and the ac, what is the voltage at 1,500 rpm?

Good luck!

Milton 07-01-2013 02:27 PM

Some more info:



amc49 07-01-2013 06:27 PM

Using a new alt to charge a dead battery is a major mistake, could pop the alt..................the alt paperwork states that but you have to read it.

And, not one word about why alt changed, or, what if done for no reason at all? Half posting does not help. Battery could be entire problem.

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