I have a 2000 Ranger 2wd 114,000 miles, what I belive is the original alternator. Recently at times the headlights are dimmining a little bit, usually for a second or two, then returning back to normal. When this happens you can also see the instument panel dim at the same time. Yesterday for the first time that i noticed, the battery light flashed for about a second and then went right off. The battery is only about 20,000 miles and two years old (however when I looked at the date on it when i bought it, it may have been sitting on the shelf at the store for a couple years before I installed it).

If this sounds like the alternator, any tips for installation that the Chilton manual might not have? I have also never bought an alternator before, are they any suggestions on what to buy as far as new/used/remanufactored?
Thanks.

 

take the truck in to autozone or orielly or some such place, they can check the charging system for ya and its free! Mine also does that but when I rev up its ok, been doing it for a long time now.

So instead og guessing go find out for sure, could maybe be the battery is going south!

 

I would take it to more than one auto part store. Several years my sons Grand Prix kept dieing, so I took it to O'Reilly's to have the battery and Alt. checked. They told me the alternator was indeed bad, so we changed it. Several day later the car refused to turn over. This time, I took the washer tank out to look at the battery. It was bone dry of water. I firmly believe that the guys at the auto part store told me the alternator was bad had no idea what they were doing.

 

as suggested you can start by having the auto parts test it..you also can put a multimeter on it and see what power it is producing.I believe you want about 14 volts at the battery with it running..........check the belt and tensioner......is the powersteering working fine......I bought my alt at autozone about 3 ears ago and it has been fine..i have the I4 it was apiece of cake....we dont know what engine you have

 

Sorry forgot to mention that's the engine is the 2.5L. Thanks for the ideas, i'll start by taking it to a couple places for a test, and i'll try to borrow a voltmeter to check the battery.

To add another piece to the puzzle just today after stepping out of the truck after a 5 minute drive I noticed a slight burning smell, popped the hood and could no longer smell it. Maybe nothing or could be my imagination, but would this be a sign of something?

While the hood was up I gave the belt a push and tension seems nice and strong, and there are no apparant problems with the power steering.

 

one of the digital multimeters I own I bought at harber frieght for $7......you can test the output at the battery with that $7 MM. I think it took me about an hour to do the alt install I forget it was 3 years ago.....look around for the burning smell....smell the alt itself. look for burnt wires etc..

 

On Thursday I will get a chance to look at the alt. I was just wondering if in the case that I have to replace the alternator, will it be necessary to charge the battery after putting the new unit in and before starting the engine for the first time? I don't have a trickle charger so I was hoping this won't be needed.

 

Don't let the Magic Blue Smoke escape! All electrical items operate on Magic Blue Smoke and once it escapes the item ceases to operate.

Seriously, also check all the cables and their connections; sometimes it's as simple as a loose/corroded battery cable on the battery or the other end.

 

I have noticed a lot of the fluffy white stuff when I go to check the oil over the past few months. Thanks for the idea- i'll give the battery posts a good cleaning.

 

Check that they haven't corroded up the cable, the strands act like a wick.
Cables are cheap.

 

I picked up a multimeter from the store and took the voltage across the battery this morning. With the engine off, the voltage only read 10.7V. From searching around on this forum I'm finding that anything below 11.5V means you have 0% charage. So I was really surprised that right after taking this voltage the engine started (although it took a couple more cranks than usual.) Now with the engine running, the voltage read 14.7V. Even after putting on all the accessories I could think off- full heat, lights, radio- it still read very close to that, around 14.6V.

I'm no expert but my first thought is this would point to a bad battery that can't hold a charge, and would indicate that the alternator is fine since the voltage with the engine running was above 14V. But the thing is, the battery is only two years and 20,000 miles old.

Over the past few days since I posted the original question the same symptoms are occurring, just maybe a little more. The main things I notice are headlights and the instrument panel dimming on and off when driving at night. Also each time I start the car it gets a little harder to start. It probably now takes twice the cranking time that it would in the past when nothing was wrong- not that much of a difference but noticeable for someone who drives the car everyday.

If it helps in troubleshooting at all, I should add that the corrosion on the positive terminal is pretty severe. It's caked on there and even with a knife I couldn't scrape most of it off. I'm a little nervous about unscrewing the bolt that holds the clamp on the terminal because its covered in corrosion and rust. The profile of the bolt head is gone.

Sorry for the long write up. Please let me know if you have any ideas.

 

Take the battery to your local auto part store and they will be more than happy to check it under a load.

 

Did you take the voltage reading touching the battery terminals or touching the cable connectors? I'm surprised that the truck would start at that low battery voltage but if you took the reading off the cable connectors, you reading could be a result of resistance between the terminal and the connector.
I'd agree though, the battery is probably on it's way out. I just replaced two batteries in my SuperDuty that were only two years old (thanks to Costco for free replacement!).
I still think you need to consider replacing the battery cables, you're only talking maybe $100.00 to replace both cables and the battery.
Good peace of mind in the winter.

BTW, a battery post cleaner (wirebrush kind) is only about $5.00 and will clean your terminals and connectors.

 

This was odd. I checked the voltage again later in the day and it read 12.31V this time. I'm not sure why it was reading 10.7V earlier this morning- I had the multimeter in the same spot right on top of the terminals and pressed and held down for a secure connection. I guess from what I've seen 12.31V would be about half charge. So I tried to remove as much corrosion as possible- there was even corrosion between the clamp and post on the positive side. I guess what I'm hoping now is that it was just a bad connection

After reconnecting the battery I'm still getting the dimming lights when I just drove it, but maybe the battery has not had a chance to recharge much yet. And now that I'm commuting by bus, my only drive most days is 5 minutes to the bus stop and back with the heat on full blast- maybe its draining from starting but does not have enough time recharging. I actually called Autozone about the Duralast battery since it should still be under warranty and they said bring the truck in, battery still in the truck. Then when I got there they said you need to bring in the battery out of the truck...so I'll keep an eye on the charge over the next few days.

Thanks for the idea on replacing the cables. There was some corrosion creeping into the cable where it's covered by tape. I'll make sure to replace that. Thanks again.

 

Chemical reaction that creates electron flow increases with temperature.