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battery was dead, Bad Alternator???


lothos

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Haven't been noticing problems with the electrical lately, but I went out to my car today and the battery was dead. Lights came on like normal but went to start my car and the lights dimmed badly and it wouldn't start.

We hooked the jumper cables up and let it charge for a while and the car was real hard to start. Eventually got it running, and I let it idle for a couple minutes.

The car died when I turned the headlights on to leave.

My buddy and I think it's the alternator, does that sound like the issue? How can I verify alternator output with my multimeter?

I think I'm going to stop at the Pep Boys up the road tomorrow morning and buy a battery so I can get home.

An ACDelco remanufactored alternator plus overnight shipping is $200 from rockauto. Now, I had my windshield replaced and I lost my heated windshield. Should I order the alternator WITH the heated windshield or WITHOUT? I'm thinking without, and I can just take that cable out?

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

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you have used a VOM before? red and black probes. touch probes to battery terminals. should be 14v or so with running car. since your battery is dead, it should read less than 12v with car off. start there.

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you have used a VOM before? red and black probes. touch probes to battery terminals. should be 14v or so with running car. since your battery is dead, it should read less than 12v with car off. start there.

Thanks for the reply joeb. I will check the battery. Do you know where I measure the alternator output?

The closest GM dealer wants $316 for an alternator, overnight shipping from rockauto is definitely cheaper.

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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I tested the battery that I pulled out of the car, it is showing 12.63.

Can anyone tell me how to test the alternator output?

Thanks guys :-)

Edit: should mention also that I was able to throw a battery in from Pep Boys and drive the car home. Dash computer showed voltage at 14.4 and by the time I got home it was showing 13.5.

Edited by lothos

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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What was the result of the Pep Boys load test on your old battery?, it should have tested bad

Your dash readout sounds correct after startup will will be 14+ and then drop as the battery charges, down to say 13.1

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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What was the result of the Pep Boys load test on your old battery?, it should have tested bad

Your dash readout sounds correct after startup will will be 14+ and then drop as the battery charges, down to say 13.1

You think it might be the battery?

I didn't have the battery tested, I am planning on bringing the old battery to Oreillys after work tonight to test the old battery and the alternator. The battery that I took out was installed Jan 2008.

I also took apart and cleaned my battery cables last fall with a wire brush and some quick drying electrical cleaner.

The old battery shows 12.63v when I tested it out of the car with my multimeter

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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also I get a noise from my serpentine belt area. Sounds like a chain rattling. Buddy heard it and says it's one of the pulleys. I bought a mechanic's stethoscope to pinpoint the noise but haven't been able to yet, will try to do that tonight.

Maybe that sound is from the alternator, and the alternator is bad? It's a 1995 after all, with 178k miles and I think the alternator is original.

I'm going to try to take the car up to Oreilly tonight and get it tested along with the old battery.

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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The battery and the alternator could be good but something could drain the battery.

That thought crossed my mind too.

I was going to order an alternator today and have it shipped overnight so I could replace it tomorrow, but I'm going to wait until I can get the car and the old battery tested tonight.

And what about the fact that the car died when I turned the headlights on last night? Wouldn't that point to the alternator not charging the battery correctly, and the extra power drain from the lights used up the rest of the battery power that we added from the other car?

I guess I'll wait and see what the test results are and take it from there.

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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The battery and the alternator could be good but something could drain the battery.

That thought crossed my mind too.

I was going to order an alternator today and have it shipped overnight so I could replace it tomorrow, but I'm going to wait until I can get the car and the old battery tested tonight.

And what about the fact that the car died when I turned the headlights on last night? Wouldn't that point to the alternator not charging the battery correctly, and the extra power drain from the lights used up the rest of the battery power that we added from the other car?

I guess I'll wait and see what the test results are and take it from there.

Because your battery was VERY low, the alternator at low RPM probably did not have enough power to keep the car running with lights on. Alternators go down gradually, it might be on its way. Because there are several unknowns, it is very important not to spend a lot on new parts without knowing what is going on. you can buy a new battery AND a new alternator and later figure out you needed none of them.

The saddest thing in life is wasted talent

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[because your battery was VERY low, the alternator at low RPM probably did not have enough power to keep the car running with lights on. Alternators go down gradually, it might be on its way. Because there are several unknowns, it is very important not to spend a lot on new parts without knowing what is going on. you can buy a new battery AND a new alternator and later figure out you needed none of them.

I agree with the throwing parts at it, however a tow home would have been roughly the cost of the battery, and I got a new battery out of the deal. There was no way to hook a battery charger up to the car where it was sitting.

I'm puzzled about why the battery was so low that the car wouldn't start. Curious to see what the results of the tests are tonight.

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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Have you double checked to be sure that the wires to the alternator aren't loose?

Also, have you checked the belt? If it's loose then the alternator won't charge properly, but it would normally cause problems with anything else that runs off it too. It's still worth checking in my opinion if you haven't.

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What was the result of the Pep Boys load test on your old battery?, it should have tested bad

Your dash readout sounds correct after startup will will be 14+ and then drop as the battery charges, down to say 13.1

You think it might be the battery?

I didn't have the battery tested, I am planning on bringing the old battery to Oreillys after work tonight to test the old battery and the alternator. The battery that I took out was installed Jan 2008.

I also took apart and cleaned my battery cables last fall with a wire brush and some quick drying electrical cleaner.

The old battery shows 12.63v when I tested it out of the car with my multimeter

Your charging rates appear good, that is why I didnt think alternator unless you are getting an intermittant problem. I had a similar problem with my 91, and it was the battery, the alternator can not run the car by itself if the battery has an internal short or dead cell. See what the result of a load test shows

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Have you double checked to be sure that the wires to the alternator aren't loose?

Also, have you checked the belt? If it's loose then the alternator won't charge properly, but it would normally cause problems with anything else that runs off it too. It's still worth checking in my opinion if you haven't.

Thanks for the suggestion. I will check the wires to the alternator. I put a new serpentine belt on not too long ago and it seemed to fit pretty well.

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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my 2yr old battery died. have had exact model replacement for 4yrs now. new stuff fails. if your alternator is charging at the proper voltage, 14v+ than it is probably ok.

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On the way to Orielly the car showed 12.2 with key on, started car and display showed 13+. Have been reading the forums and this is supposed to be a good sign.

My alternator tested ok according to the Orielly guy. The old battery was 91% charged but failed the test he did.

Thanks everyone for your help, I appreciate it :-)

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

5% discount code at RockAuto.com - click here for your discount!

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fixed my alternator on 04/09 and voltage is fine but think battery is funky. shut off car and turn key on and it says 12.1. than it goes to 12, 11.9, 11.8 within 30 sec. i think my battery may have been affected by the alternator not working right the last several months. and here i thought it was ok.

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