92 FJ80 with electrical issues - replaced alternator

[kambei]

Hey everyone,

I've been having odd power issues on my 92. I first noticed my stereo turning off and on and then realized that I had a draining battery when it was starting to struggle to start, turning over slowly.
First time I charged the battery and all was well until I started experiencing the same symptoms again and was almost stranded up in the mountains.

I took it to a battery place and the battery checked out as healthy so it must be the alternator not working and not charging right? I replaced it last night and fully recharged the battery overnight and already today I am experience some of the same symptoms as before. The lights are dim, the stereo is turning off and on, and at times the digital clock on the dash is completely blank.

Does anyone have any idea what could be going on with this? I thought replacing the alternator would be a done deal, but it clearly is not.

 

[gummycarbs]

I don't know anything about the 3F-E, but here goes:

If you fully charge your battery, then take it off the charger for an hour (better yet, overnight), what is its resting voltage? Ignition off, doors closed. I don't particularly trust battery testers, especially if they don't put in the right capacity.

It's not unheard of for a new (usually rebuilt) alternator to have a bad voltage regulator. I'd probably start by figuring out which wire on the plug is used for sensing battery voltage and verify that it's getting the same voltage you see at the battery. Check other obvious stuff, like is the output cable from the alternator in good condition and low resistance, are the fusible links all good, check all the fuses.

You say the lights are dim and the clock and stereo go out, but did you verify what the voltage is at the battery when this happens? Maybe you're charging fine and have something unrelated like a flaky ignition switch (not the lock cylinder) or broken or corroded wiring elsewhere.

 

[kambei]

I’m pretty sure the new alternator just isn’t working at this point. It came with an adapter cable for the connector so I’m wondering if there’s an issue with that.
Sadly I got stuck when running an errand last night, so I’m going to have it towed to a local Toyota specialist in town.

 

[Michael Hanson]

Hi, Alternator made by communist Chinese are no good. Get your original rebuilt.

 

[jonheld]

How about some diagnostics as opposed to throwing parts at it? Use a volt meter and check across the battery terminals.
For a standard wet cell battery: 12.6 at rest (cold, non running engine) is fully charged. If this battery was severely discharged it will not come back to its full voltage.
Engine running: approx 14.4 volts says good alternator and good battery, depending on state of charge.