Confirming Alternator Problem

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Kanger328

New member
I did my research on here already, but wanted to confirm before I drop the $$$ for a new alternator.

My Runner has been dying...battery light on, losing power (dim lights, unable to drive past 35 mph, engine bogging down when turning on lights or trying to open/close windows), barely limped home yesterday. Replaced battery today under warranty, vehicle runs fine now, but battery light is still on. Used voltmeter and reads about 12.5V at idle and slightly lower (12.08) when giving throttle.

So, take the plunge and replace alternator? Thanks in advance!
 
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Sounds like it. You can get it tested at a parts place. First, I'd get a good look at all of the connections on the alternator and make sure nothing is corroded or loose. If everything checks out, start your truck and disconnect the battery terminals. If the alternator is good, your truck will keep running. If your engine dies when you disconnect the battery, the alternator is toast.

Most of the time the brushes are just bad and can be rebuild for much cheaper than a new alternator if you feel inclined. Search around you'll find lots of stuff about this.
 
If your battery is brand new... 12.5V is a little low at idle. With the car on, you should be around 14v on the multi-meter when charged.

You could get a new one, or rebuild as Miller suggested. Also, consider the Big 3 upgrade after you have a new or rebuilt alternator on there.
 
swap the stock alt out for a CS144... the same cost as a new remaned denso(the only way to go if staying stock), and the CS144 puts out like 130amp stock.
 
txclimber said:
Most of the time the brushes are just bad and can be rebuild for much cheaper than a new alternator if you feel inclined. Search around you'll find lots of stuff about this.
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Millerad1651 said:
Have it checked first. If it is the alternator, buy some new brushes and rebuild it. I spent $8 and about 2 hours. Took everything apart, cleaned everything really well, and replaced the brushes. It has been running as good as new since then.
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Thanks for that info. Actually didn't even think about rebuilding. Sounds like a much more cost effective option.
 
the kid said:
swap the stock alt out for a CS144... the same cost as a new remaned denso(the only way to go if staying stock), and the CS144 puts out like 130amp stock.
Click to expand...

I was actually considering this, but some folks say it's a direct fit, others say you need various different parts to make it fit. I rather not do it if it's not direct fit...but I see conflicting answer...
 
Kanger328 said:
I was actually considering this, but some folks say it's a direct fit, others say you need various different parts to make it fit. I rather not do it if it's not direct fit...but I see conflicting answer...
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I assume [MENTION=60147]the kid[/MENTION] has one in his rig if he's promoting it...

[MENTION=60147]the kid[/MENTION]?
 
You'll need a few washers for the mount, a slightly longer belt (same size as the power steering pump belt worked for me), and either an adaptor (if you don't like messing with stock wiring) or plug-pigtail to splice in.

It's a piece of cake. I stuck a bit more part number info in Doc's already excellent thread.
 
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0xfded said:
You'll need a few washers for the mount, a slightly longer belt (same size as the power steering pump belt worked for me), and either an adaptor (if you don't like messing with stock wiring) or plug-pigtail to splice in.

It's a piece of cake. I stuck a bit more part number info in Doc's already excellent thread.
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i didnt change the belt, im running the stock belt, i just loosened up the adjustments on the alt tension... our alts have like 3+" of adjustment. no need to replace the belt
 
the kid said:
i didnt change the belt, im running the stock belt, i just loosened up the adjustments on the alt tension... our alts have like 3+" of adjustment. no need to replace the belt
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Really? There was no way in hell I was getting that belt around the new alt when I swapped it in. Even at full inward adjustment, I couldn't get it on.

They were brand new belts though, and maybe different lengths than stock. I ended up using a Gates K040420 (same as the PS pump) and it fit perfectly.
 
the place i ordered my alt from sold it to me with a pulley that was a direct fit... when purchasing the alt i told them what vehicle i planned to use it in so maybe they swapped pulleys before shipping it to me idk. all i know is it was a direct swap.
 
Kanger328 said:
I was actually considering this, but some folks say it's a direct fit, others say you need various different parts to make it fit. I rather not do it if it's not direct fit...but I see conflicting answer...
Click to expand...

I just did my cs144 swap. All you need is the wire harness to the cs144 and you splice it into the stock wires. It's super easy slides right in and you also need three washers. That's it. And you get wayyyy better amps.
 
FFFFFFfffff...this forum I swear. I'm looking at all these links and wanting to drop more and more money into my rig. Upgraded alternator, big 3, rectifier (?), etc...problem is I'm on a bit of a budget, haha. Thanks guys for all the input.
 
Kanger328 said:
FFFFFFfffff...this forum I swear. I'm looking at all these links and wanting to drop more and more money into my rig. Upgraded alternator, big 3, rectifier (?), etc...problem is I'm on a bit of a budget, haha. Thanks guys for all the input.
Click to expand...

Seems like you have a serious case of the mod bug bites.
 
So it ended up being the alternator brushes. Paid $5 and replaced the brushes and reinstalled. Runs like a charm. Thanks to [MENTION=63686]txclimber[/MENTION] [MENTION=75483]Millerad1651[/MENTION] for the info on this repair.
 
Nice. I love that we can rebuild expensive components on these trucks! It saves so much money. I spent $5 rebuilding my alternator, and $20 rebuilding my wife's starter. Each of those would easily been a couple hundred dollars to replace.
 
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