truck overcharging

[Joust]

hi guys.
I'm in a bit of a panic here.
my truck has had the charge light coming on since I bought it. it is intermittent light sorta thing.

today I put my digital multimeter on the lighter socket to monitor the voltage.
when I left home the voltage was 14.25vdc and the charge light was on.
it was like that most of the way to work.
then the lights went off (normal Dash display now) and the voltage jumped to 16.25 and it slowly creeped up and actually touched 18vdc by the time I got to work.
when it touched 18v the abs light flickered on. once I got to work i verified on the battery directly that the voltage was high and it was.
i'm thinking this has to be a problem with the wires that go into the side of the alternator.
I'm looking in the FSM and cannot see where these wires go.
any ideas?

EDIT:
I pushed on all the connectors in teh charging circuit before I started the truck to drive home after work.
the voltage stayed at 4.15 all teh way home and the warning lights stayed on.

I ordered a new Alt.
What concerns me is that when the thing is working properly (outputing 14.25Vdc) the charge and Parking brake lights are on. When the lights go out, the alt is outputting too much voltage. explain that....

 

[WarDamnEagle]

Sounds like a bad voltage regulator to me but I'm not an expert on those. Could be something else but I don't know what else off the top of my head. I do know that it needs to be repaired quickly as you will ruin your battery.

 

[pappy]

The gauge should show 14V in normal operation. The higher voltages you have are not normal. It would help to know what you are working on. I would agree voltage regulator, and they are internal on new trucks (1984+?). Best to just get a reman alternator from Toyota. Make sure your connections are tight at the alternator first.

 

[Bogo]

Sounds like a bad voltage regulator to me but I'm not an expert on those. Could be something else but I don't know what else off the top of my head. I do know that it needs to be repaired quickly as you will ruin your battery.

Nothing else can do that. The voltage regulator is fused and not cutting back the charge current. If this is the original alternator go get a replacement voltage regulator and swap it into the alternator. While your at it, also replace the brushes. Combined it will be cheaper than a rebuilt and will likely last much longer.

Until you get it repaired, drive with your lights and stereo on. You need to use up that extra electricity or it will try to stuff it into the battery and you will end up replacing it too. If it is a serviceable battery check the water levels and top off with deionized distilled water if needed.

 

[Joust]

Well,
I fixed it.
I bought the new Alternator to install if my suspiciouns turned out to be wrong.
but, they were not. I was right. the White "sense" wire going back to the regulator had a knick in it and corroded right through. I put a splice in it and put it all back together with confidence and fired up the truck. It works like a charm.
The regulator was just fine.

 

[Bogo]

Well,
I fixed it.
I bought the new Alternator to install if my suspiciouns turned out to be wrong.
but, they were not. I was right. the White "sense" wire going back to the regulator had a knick in it and corroded right through. I put a splice in it and put it all back together with confidence and fired up the truck. It works like a charm.
The regulator was just fine.

What year truck?

 

[Joust]

1995 22re manual.

 

[2ndGenToyotaFan]

Glad you found the problem!!! I'm re-doing some of my Alt wiring after the main bat cable lost it's connector and grounded out on the alt.... No harm done though... (Or so I'm hoping...)