Alternator voltage with engine running

[Toystory2]

Troubleshooting a potentially bad alternator - 2007 V6 @ 163k. Believe it’s the original alt. Tested voltage at the alternator lead with truck running, and got about 0.03v. Even if the alt bad, shouldn’t this still read around 12.6v? Makes me wonder if there’s a bad connection b/t alt and battery.

Batt voltage w/ engine running was 12.5v. I know that means it’s getting nothing from alt.

140a fuse looks ok. Is there another fuse for it?

Checked ohms from batt to alt and got 0. Any other test I could do to rule out wiring?


Thanks to anyone who could chime in!

 

[riceandpho]

did you check the alt-s fuse? that is the charging fuse i think.
also your brush might be worned.

 

[Toystory2]

did you check the alt-s fuse? that is the charging fuse i think.
also your brush might be worned.

I checked the 140a in the fuse box, is this a different one? If so, where is it located?

 

[riceandpho]

its in the fuse box also, its the smaller ones. your fuse box cover will show
7.5amp

 

[Toystory2]

its in the fuse box also, its the smaller ones. your fuse box cover will show
7.5amp

Thank you kindly, I’ll check it out

 

[Buckaroo]

Checked ohms from batt to alt and got 0. Any other test I could do to rule out wiring?!

Resistance is not the correct test - you need to look at voltage drop.

https://www.youtube.com/watch?v=EMS8On17BnM

 

[Toystory2]

Resistance is not the correct test - you need to look at voltage drop.

#How to test your #alternator voltage drop test - YouTube

Thanks for the tip. Just ran this test and got between 0.02 -0.09 on the positive circuit. Got 0.0 on the negative circuit. So looks like there’s not much drop at all.

 

[Buckaroo]

So wiring looks good. If you are going to replace it, I suggest Denso Reman from RockAuto....

 

[Toystory2]

So wiring looks good. If you are going to replace it, I suggest Denso Reman from RockAuto....

Thanks, I got a Toyota reman from EBay, which I believe is Denso anyway.

 

[riceandpho]

did you consider doing a high output alternator?
any large electrical add ons?
im using the mechman 240a, its pretty good for my needs

 

[Toystory2]

did you consider doing a high output alternator?
any large electrical add ons?
im using the mechman 240a, its pretty good for my needs

I don’t have any add-ons, but you bring up a good point. Now would be the perfect time to upgrade if I was going to.