Real Time help: Alternator won't charge, no charge light (1 Viewer)

[Zhenya]

Hi,
I am moving and towing a trailer. All the sudden the oil pressure seemed to drop. Then I lost my radio, etc. I even stalled once and had to get jumped.

Once I arrived I started troubleshooting.

I have 12.4 at the battery after a jump. 12.4 at the alternator to ground which seems to me it's not charging. The charging light however isn't illuminating.

Is it a bad alternator, any other ideas?

 

[Trapper50cal]

I'm not sure that the oil pressure is related to charging system in any way...but it seems as though the alt isn't charging the battery.

I've had a battery die and give the same symptoms (as far as stalling) but the alt was trying really hard to charge, the battery just wasn't taking any of it.

 

[Zhenya]

I'm not sure that the oil pressure is related to charging system in any way...but it seems as though the alt isn't charging the battery.

I've had a battery die and give the same symptoms (as far as stalling) but the alt was trying really hard to charge, the battery just wasn't taking any of it.

The oil pressure was just the first gauge to go. The rest went shortly after.

Just wondering if there is a secret fuse or common fix for this issue which doesn't mean the alternator is dead.

 

[The Machinist]

Sounds like what happened to me a few weeks ago. I'd remove your alternator and take it to a parts store to have it tested.

 

[inkpot]

If your battery voltage is extactly the same when running and when shut off, then the alternator is not charging anything. Sounds like time to rebuild/replace. John

 

[Zhenya]

He charge light isn't coming all at all. Does the exciter wire run through the charge bulb?

 

[lovetoski]

He charge light isn't coming all at all. Does the exciter wire run through the charge bulb?

The exciter wire is one of the wires off of the back of the alternator.

I would do a couple of simple tests to see if you can narrow down where the problem is.

Sounds like you have a multi-meter, which is essential. Connect it to the battery, set to voltage. You'll do four tests, two at idle, two at 1500 rpm. One with no loads, the second with everything (except wipers) electrical turned on (everthing - lights, both fans on high, rear defrost).

At idle, no load, you should have 13.5 +/- volts.
At idle, with load, you should have 12.5 or fewer volts. The longer you idle with the loads on, the lower the volts will go. The alt doesn't put out enough amps at idle to cover all of these loads so that battery is drawing down.
At 1500 rpm, no load, you should have 14.0 +/- volts.
At 1500 rpm, with load, you should have 13.5 +/- volts. (The alternator should put out enough amps at this rpm to cover all electrical loads in the truck.)

Post back with what you find.

 

[shady]

I also had a charging problem a while back. No caharge light, just watched the volt meter drop slowly.

Got home and was about to pull the alternator to have it tested and thought I would check the fuses before I went to the trouble.

Has a fuse for the charging system, pushed on it and it started charging again.

 

[Cruiserdrew]

My guess is a bad battery. The charge light operates through a relay, but is not needed for the alternator to work. The exciter wire is switched by the ignition switch, and is independent of the charge light.

The diagnostics are really easy.

Fully charge your battery with a charger (you can't reliably test a discharged battery) and have it load tested at the parts store. If it's good, re-use.

Pull the alternator. This is a 10 minute job on the FJ60 due to the top-mount location. Have it tested and get a new one if it's bad.

Have you thought about swapping in a known good battery and apply Lovetoski's voltage tests? If everything is back to normal, ie 13-14 volts at the battery when running, just replace the battery.

 

[Zhenya]

I also had a charging problem a while back. No caharge light, just watched the volt meter drop slowly.

Got home and was about to pull the alternator to have it tested and thought I would check the fuses before I went to the trouble.

Has a fuse for the charging system, pushed on it and it started charging again.

I checked the fusible link and that had continuity through it. I also tested the continuity to battery through the exciter wires. I will check the fuse one more time. If the fuse is intact, does that mean the charge light should come on?

The exciter wire is one of the wires off of the back of the alternator.

I would do a couple of simple tests to see if you can narrow down where the problem is.

Sounds like you have a multi-meter, which is essential. Connect it to the battery, set to voltage. You'll do four tests, two at idle, two at 1500 rpm. One with no loads, the second with everything (except wipers) electrical turned on (everthing - lights, both fans on high, rear defrost).

At idle, no load, you should have 13.5 +/- volts.
At idle, with load, you should have 12.5 or fewer volts. The longer you idle with the loads on, the lower the volts will go. The alt doesn't put out enough amps at idle to cover all of these loads so that battery is drawing down.
At 1500 rpm, no load, you should have 14.0 +/- volts.
At 1500 rpm, with load, you should have 13.5 +/- volts. (The alternator should put out enough amps at this rpm to cover all electrical loads in the truck.)

Post back with what you find.

I ran the test, for all non-loaded conditions it was at 11.5. I was afraid to run a load test. I lost my jump vehicle and needed to make sure I could start the truck up to move it before I received a parking ticket.

My guess is a bad battery. The charge light operates through a relay, but is not needed for the alternator to work. The exciter wire is switched by the ignition switch, and is independent of the charge light.

The diagnostics are really easy.

Fully charge your battery with a charger (you can't reliably test a discharged battery) and have it load tested at the parts store. If it's good, re-use.

Pull the alternator. This is a 10 minute job on the FJ60 due to the top-mount location. Have it tested and get a new one if it's bad.

Have you thought about swapping in a known good battery and apply Lovetoski's voltage tests? If everything is back to normal, ie 13-14 volts at the battery when running, just replace the battery.

I will pull both this afternoon and take them to the parts store. How reliable is the parts store test?

 

[Creeper]

I also had a charging problem a while back. No caharge light, just watched the volt meter drop slowly.

Got home and was about to pull the alternator to have it tested and thought I would check the fuses before I went to the trouble.

Has a fuse for the charging system, pushed on it and it started charging again.

Same issue. Ended up buying a new alternator that also did not work. I got a little frustrated and ended up pulling all the fuses. One must have been loose and something clicked and i now have a working charging system. Be sure to check your fuses. At least i have a spare alternator now

 

[lovetoski]

I am not a fan of spending money if you don't have to by replacing parts unless you know they are bad. So, I'd charge your battery overnight and then redo the volt test.

If you know the battery is ok, then 11.5 volts with no load means an alternator problem. If you take it to a parts place and it tests bad, they'll sell you a remanufactured one. However, often it's just the voltage regulator. If you have an external VR, it's easy to swap it out, and much less expensive than the entire alternator.

 

[Trapper50cal]

My VR was out when I bought my truck, but the alt was throwing too much as a result, like 17...THe VR won't OVER regulate, will it? I was under the impression that if it was undercharging or not charging at all, then it isn't the VR...incorrect?

 

[Cruiserdrew]

My VR was out when I bought my truck, but the alt was throwing too much as a result, like 17...THe VR won't OVER regulate, will it? I was under the impression that if it was undercharging or not charging at all, then it isn't the VR...incorrect?

^Sounds like it just stopped regulating the voltage, and so the voltage could spike with RPM. The diodes can also fail in the rectifier and then it won't make the proper voltage either.

I do not rely on the auto parts places for testing of alternators. It's a decent place to start but won't tell you what's wrong with it. If you can, find an old fashioned "auto electric" place that does in house rebuilds. I would not blindly replace the VR if you have no idea that's the problem.

If you do get a reman, get a Toyota reman. They use the proper Denso parts and it will literally be as good as new. THe ones from auto parts places are often poorly done and not a long term solution.

 

[Trapper50cal]

I put a Denso VR on my overcharging ACDelco reman. and it's doing swimmingly...14.5-14.6

 

[jozlod]

Does the alt light turn on when you turn the ignition on (not running)? Cause if it doesn't, thats the place to start looking. Not sure if you've stated this or not in your comments, just checking you've looked at it.

Best of luck.

 

[Haggis]

Anyone have a Mean Green Alternator in their rig?

 

[lovetoski]

My VR was out when I bought my truck, but the alt was throwing too much as a result, like 17...THe VR won't OVER regulate, will it? I was under the impression that if it was undercharging or not charging at all, then it isn't the VR...incorrect?

I have had the cheapo autozone alternator in my 60 go "funky" twice. Once it overcharged, once it undercharged. Both times I replaced the VR and the problem went away. I now carry a spare VR...probably should just put in a Toyota reman alt though (plus would still carry a spare VR).

 

[hjdca]

My alternator just went out in my '01 M3.. The dealers wanted $550 for a remanufactured and online was like $250 or so... I just removed the alternator and took it to "Jose's Alternator". He rebuilt it for me, the brushes were worn, new voltage regulator, new bearings, etc.. It was only $80 and it works perfectly... Sometimes it is cheaper to rebuilt your OEM alternator...

 

[Taraz]

Some fotos, i am using WG cable to exite the alternator, as it is the only one with a 13v/14v output...

Cant get the WLight blue, to bring any voltage from the regulator out!

Brand new regulator as you guys can see on fotos, also running a direct cable to the battery, to make sure it gets there, is that a problem??? Should this cble always pass the regulator?

As i said before, now its charging but not keeping the batery alive!

Regards, and thanks again everyone!