ECU, Wiring, Sensors
By pyang004
#337177 Having alternator problems. What is the best alternator for our cars? What do you have and experiences with others.

I had random engine shut off issues last year and changed out my alternator to try and solve the problem. Turned out it was a bad iginition switch. The alternator I bought was a remanufacture lifetime warranty Duralast from autozone. I try to get lifetime warranty whenever I can. Just too tempting, but in this cast it backfired.

It's been almost a year and the battery dash light came on one morning and the idle was bad. Took it in to get it replaced and a month later I'm having issues again. Battery light comes on at idle usually only when headlights are on. Over 1000 rpm and the light turns off. I try to keep the car in neutral at stops and rev the engine if needed.

My issue now is I don't really want to bring it in for the limetime warranty replacement if this is gonna keep happening. I was looking at some other options, but it seems all major chain autoparts stores have the same issues. Random at best to get a good alternator to last more than a year.

Is there a difference between a *NEW alternator versus a remanufactured one? Do they use the same crappy parts?

Autozone Duralast new/reman
Napa standard/pro/premium new/reman
Napa Bosch reman
O'reiley Ultima reman
Pep Boys Prostart Platinum new
Pep Boys Prostart reman
Local Shop rebuild

What's your exp and recommendations? If local rebuild, what parts are good or do they just use cheap parts? Would they rebuild my cheap Autozone reman or should I pull a used one from the junk to rebuild? What brand/markings is on the OEM alternator if I pull one from the junk?

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By suspendedHatch
#337212 They're all the same as far as reliability goes. I've used AutoZone alternators and never have had to replace them again. I think you must have some other problem that is killing your alternators.

How's your alternator wire? How's the connection at the fuse box? How are the engine grounds?
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By Zackman
#337220 ^ What he said. Check your grounds and check to make sure the power wire that goes to your fuse box from the alternator has a strong connection. While the car is running, check the power leads with a voltmeter from the actual power terminal of your alternator, and the terminal in the fuse box. You can get a friend to vary idle speeds to check if your alternator it putting out more or less power at different engine speeds. If your voltage varies at all from the beginning of the power cord (Where the alternator is) to where it connects to the fuse box, you probably have a bad wire. Your alternator should read around 14.45 volts while running. Your battery should be above 12.2 volts while sitting. Check tension on the belt too. If there is slack your alternator won't charge properly.

I have used a high output 160 amp alternator from altstart and have not had any power issues since, (Even with my 3800 watt system). It's recommended you have a better wire for the upgraded alternator and cut a little hole in the fuse box lid to accommodate the new alternator power wire.

Here's a link to the alternator. ... 0951535392

If your battery has been operating with a poor alternator for a long time you may want to consider getting a new one of those as well.
By pyang004
#337246 Battery was replace 1.5 years ago. A few months before the alternator was replace a year ago. Battery ground wire was replaced at the same time the battery was.

Last month when I replaced the alternator... Drove the car into town to catch a movie. Everything was fine. Left the theater to come back home and at every light when I stepped on the brakes the battery light came on. Got home tested stepping on the brakes to try and replicate the problem, but everything seemed fine. Throughout the previous year I drove the car round trip 1 hour to work, 5 days a week with no problems. The next day I started the car to go to work and the light stayed lit and the car idled poorly. Used another car to go to work. Got off work and pulled the alternator. Tested at Autozone and he said it was done.

Within the last year I have not touched the grounding wires other than to disconnect the battery to remove the alternator. Not electrical work has been added or modified other than replacing a dead headlight bulb and alarm system that was installed 2 months after I bought the car. At the time I replaced the alternator last year, I also replaced the water pump and all 3 belts.

The wires look to the alternator looks fine for their age. All connected firmly. Belt is tight. Doubled checked it already before posting.

I'll double check the grounds and clean the ends. Probably replace the front engine ground with a new wire. Then do a voltmeter check on what you guys listed. I'll post my findings when done.

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By suspendedHatch
#337251 You can resistance test the wires by disconnecting them at both ends and setting the meter to 200 Ohms. I've found that even old wires usually come in around .3 or less. More than .5 is a problem.
By pyang004
suspendedHatch wrote:You can resistance test the wires by disconnecting them at both ends and setting the meter to 200 Ohms. I've found that even old wires usually come in around .3 or less. More than .5 is a problem.

So I disconnect the wire from the fuse box and alternator end. Now the wire is not connected to anything. Set the meter to 200 ohms and touch the negative end of the meter to one end and touch the positive end of the meter to the other end of the wire.?
By pyang004
#337296 Here is what I found testing various points.

Battery ends positive and negative.
Fuse box end connecting to battery positive.
Fuse box end connecting to alternator.
Alternator end connecting to fuse box.

Grounds - Various engine parts, chasis bolts, core support bolts, battery.

*Note below that "Battery Side" consist of battery positive end, fuse box end connecting to battery, and fuse box end connecting to alternator. "Alternator" consist of positive on the alternator.

No key in ignition/Gear in park/Lights off
Battery Side: 12.75v
Alternator: 12.60v

Key on "ON" position/Gear in park/Lights off
Battery Side: 12.50v
Alternator: 12.43v

Key on "ON" position/Gear in park/Lights on
Battery Side: 12.10v
Alternator: 12.00v

Engine idle/Gear in park/Lights off
Battery Side: 13.90v
Alternator: 14.10v

Engine idle/Gear in park/Lights on
Battery Side: 12.93v
Alternator: 12.96v

Engine idle/Gear in drive/Lights off
Battery Side: 13.08v
Alternator: 13.18v

Engine idle/Gear in drive/Lights on
Battery Side; 12.54v
Alternator: 12.61v

Engine 1000rpm/Gear in drive/Lights off
Batter Side: 13.62v
Alternator: 13.86v

So when the car is not running the battery is putting out more voltage than the alternator. Which makes sense, since the more length of wire I test from the source (the battery) the less voltage I should get. So when the car is running, the alternator is putting out more voltage than the battery. Because now the alternator is generating more voltage to charge the battery. So if the voltage drop below that battery's base reading (12.75v) the battery should read slightly more than at the alternator end - with the engine running or not. If the voltage reading is above the battery's base reading than the alternator should read more than the battery end - only occurs when the engine is on, generating power to the alternator.

But with the lights on... there is a significant drop in voltage.
Base/Light off: 12.60v
Base/Light on: 12.10v
Difference: 0.5v

Idle/Light off: 13.90v
Idle/Light on: 12.93v
Difference: 0.97v

Idle/Gear in drive/Light off: 13.08v
Idle/Gear in drive/Light on: 12.54v
Difference: 0.54v

1000rpm/Gear in drive/Light on: 13.62v

All the grounds seem to be good. I'm gonna replace the engine ground and transmission ground anyways when I get a chance. What size gauge is the alternator wire? I'll probably replace that and the positive wire on the battery while I'm at it.

I still think it's just the alternator. I guess I'll just have to keep exchanging it until I get one that works. Still it is good to know what other things can cause this problem and eliminate all of them. I've had most all parts replaced already. I want to keep this car as an excellent daily driver. So I don't mind replacing any questionable part even if that's not causing any problems at the moment. Just good to know that there's a new part on the car instead of a 18 year old part that can fail at any moment.
By pyang004
#341569 Just an update on this if anyone finds this post in a search.

I replaced some power wires and ground wires with 4 gauge wires. With the same readings from the previous post. Checked my spark plugs and cleaned them, with the same results.

The wires I replaced are as followed:

Battery Ground to Chassis
Battery Power to Fuse Box
Fuse Box Power to Alternator (old wire disconnect from both ends)
Fuse Box Power to Starter (I did not change)
Transmission Ground to Chassis.
Engine Ground to Radiator Core Support
Engine Ground to Strut Tower (Added)

So now I certain it's the alternator. I've just been super lazy and didn't want to replace the alternator again since this post was created. The car still has the same issue, but it is still very driveable.
By pyang004
#343880 So the low readings was because of the alternator. I took it in to get it checked and it was bad. This is now the 3rd re-manufactured lifetime warranty alternator from Autozone. Let's see how long this one will last.