12.4 volts???

[jvazquez53]

Having problems with voltage. Engine off, 12.8 volts. Engine on, 950 RPMs AC off, 13.2+-. Engine on AC on, 950 RPMs 12.4, sometimes lower! I know the AC blower probably sucks some voltage, but that much?

 

[george_tlc]

How many miles on the brushes in your alternator?

You should be up around 14.4V with AC and other loads off and engine ticking along at a fast idle - assuming your battery isn't knackered.

Presumably you are measuring battery voltage directly across the + and - posts.

cheers,
george.

 

[jvazquez53]

How many miles on the brushes in your alternator?

You should be up around 14.4V with AC and other loads off and engine ticking along at a fast idle - assuming your battery isn't knackered.

Presumably you are measuring battery voltage directly across the + and - posts.

cheers,
george.

" remanufactured New" about one month, maybe ten miles of use.

 

[george_tlc]

Aftermarket 'reman' or a toyota core? And you replaced the alternator why?

cheers,
george.

 

[jvazquez53]

Aftermarket reman, its what the truck had since day one years ago. I replace it because t has "lifetime warranty". Thinking the problem is the alternator. Honestly, I dont know whats inside. I've been thinking getting a Bosch or a Denso. I dont know if those do come brand new. One mechanic told me he can get a higher amp alternator and that should take care of the problems.

 

[george_tlc]

The stock alternator should have no problems keeping up with normal loads (AC, Lights etc etc).

The higher output alternator blah from the mechanic is just that, blah...

The alternator on an 80 is pretty simple, it has an internal regulator so simple hookup. If you aren't getting at least 14V at idle then you either have a dead battery (sucking the alternator output down), a slipping belt, bad alternator or bad wiring from alternator to battery (alternator goes through a fusible link to charge the battery).

So, give some more history here since my crystal ball seems fogged up... Did you replace the alternator because the previous alternator had low output etc and the replacement performs just the same (as badly)? Was the original alternator working ok and then you noticed a problem? i.e. help us to help you...

Oh, and 'lifetime warranty' items aren't always a great choice for long term reliability.

cheers,
george.

 

[richardlillard1]

Mine sits around 13 most of the time, even as low as 12.2 sometimes while driving. It has done this for the last 100,000 miles so I’m not super worried about it

 

[george_tlc]

12.5V is not fully charged. Are you measuring with a decent meter or relying on the dash meter?

Alternator that is actually working correctly and a decent meter on the battery posts should read around 14.4V when all is good.

No way that 12.5V would be something I'd not be worrying about (assuming again, good meter and across the battery terminals with engine at fast idle).

cheers,
george.

 

[richardlillard1]

12.5V is not fully charged. Are you measuring with a decent meter or relying on the dash meter?

Alternator that is actually working correctly and a decent meter on the battery posts should read around 14.4V when all is good.

No way that 12.5V would be something I'd not be worrying about (assuming again, good meter and across the battery terminals with engine at fast idle).

cheers,
george.

Reading off the scan gauge, but it’s done this for years, so I don’t care.

 

[nukegoat]

Reading off the scan gauge, but it’s done this for years, so I don’t care.

Yet your fridge has problems with the low voltage cutout. shocker

 

[richardlillard1]

Yet your fridge has problems with the low voltage cutout. shocker

Not with the newer, bigger battery installed yesterday. Numbers are reading the same as before, but it’s working.

 

[nukegoat]

Not with the newer, bigger battery installed yesterday. Numbers are reading the same as before, but it’s working.

Oh ok sounds totally logical to me. Theres nothing wrong with this reasoning

 

[george_tlc]

Scanguage reading is meaningless. Battery voltage needs to be measured with a decent meter at the battery terminals.


cheers,
george.

 

[jvazquez53]

The stock alternator should have no problems keeping up with normal loads (AC, Lights etc etc).

The higher output alternator blah from the mechanic is just that, blah...

The alternator on an 80 is pretty simple, it has an internal regulator so simple hookup. If you aren't getting at least 14V at idle then you either have a dead battery (sucking the alternator output down), a slipping belt, bad alternator or bad wiring from alternator to battery (alternator goes through a fusible link to charge the battery).

So, give some more history here since my crystal ball seems fogged up... Did you replace the alternator because the previous alternator had low output etc and the replacement performs just the same (as badly)? Was the original alternator working ok and then you noticed a problem? i.e. help us to help you...

Oh, and 'lifetime warranty' items aren't always a great choice for long term reliability.

cheers,
george.

The alternator issue started when I noticed that when I turned the AC on, the RPMs would not go up. The RPMs problem got solved with a Holley carb AC solenoid. I have two trucks and the other works as it supposed. The truck remained parked after last year hurricane for quite some time. When I started to use it again, that's when I started to pay attention to these issues. I just had the alternator rebuilt about a month ago, reason, trying to find out if the voltage issue would get fixed and probably you are right, who knows what parts they put in it.
I know the belts are fine, so, tomorrow, Im going to test the battery, next the alternator, the fusible link and the wiring. Someone suggested me to replace the alternator wiring with 4 gauge wire. That wire hasn't been touched. The rest of the wires, (battery positive/negative and ground were changed, I did had access to 2 gauge, probably an overkill. In case the alternator is the bad one, any suggestions, brand preferences?

 

[george_tlc]

Well, most folk on mud would say to go with a toyota reman unit. I'm guessing rockauto etc would have something like that.

The stock alternator would be fine with 8g or 6g if you want to size it up. It's not like it will be pushing 100+ Amps for any significant time.

Check the wiring to make sure it is solid and all lugs are secure and clean. Can't hurt to remove connections and give them a clean, especially if the vehicle sat for an extended period of time. Check both positive and ground connections. Put a decent meter right on the battery lugs to measure the alternator output. You could also probe the output connection right at the alternator to verify it's not a cable issue.

I wouldn't be changing to heavy gauge wiring blindly, yes it may solve the problem, but only because you'll be potentially changing a damaged/weathered wire or cleaning lugs etc just by replacing things. Best to be methodical when debugging electrical issues.

cheers,
george.

 

[Rifleman]

" remanufactured New" about one month, maybe ten miles of use.

Hate to tell you this, just because you replaced it a month ago doesn't mean it's not bad.

Pull it off, and take it back to the auto parts store where you bought it, and have them bench test it.

I can't tell you how many time's I've had to replace what were supposed to be "good" re man's.

Now I've started having the auto parts store test them on their bench tester before they ever leave their store to make sure they are up to spec.

 

[Jgrauman]

Trickle charge your battery for a few days to make sure it's getting a full charge. If you drive a lot of short trips you may not be doing your battery justice. My Optima would do the same to my alt output when not fully charged. I would run 12.2-12.8 once I charged up the Optima I run at 13.8-14.2

 

[BILT4ME]

Having problems with voltage. Engine off, 12.8 volts. Engine on, 950 RPMs AC off, 13.2+-. Engine on AC on, 950 RPMs 12.4, sometimes lower! I know the AC blower probably sucks some voltage, but that much?

Do you have a factory RS3000 alarm system?

I had similar symptoms.
I replaced the battery, as my Ultragauge would register dropping voltage as I sat at a stop light, and battery tested as bad.
Problems persisted.
Replaced the alternator, as I assumed that the alternator was not keeping up and I had no idea if the alternator was original or not with 250K on the truck. (turns out it had a reman on it). New one did better, but not enough. Over time, it improved (why, I don't know....) but it is an O'Reilly special.
Replaced the battery again. Helped even more.
Had a no-start on the truck due to what appeared to be dead battery. Tried to jump and starter dead.
Replaced the starter.
Problems solved.

I believe I was having a constant drain from bad starter contacts, but I never measured it. Some of this stuff I replaced because I figured it was time so it was kind of PM as well as throw money at it to fix. I don;t normally do things that way, but I needed to refresh the parts anyway.

I also discovered later that the alarm system was causing random drains on the battery. It would go dead overnight sometimes, other times not. After the alarm decided to wig out, I ripped it out and have not had ANY electrical issues since.

 

[danthman114]

check the cells in your battery...

 

[SmokingRocks]

I had a non toyota parts store reman alternator for about a month. It never produced the right voltage, replaced with a toyota reman and all my problems went away.

That said the blower motors in our rigs often wear out and consume huge amperage, so this may be your issue.