Charging system problem, help!

I checked them last tuesday. Nut and bolt were very very corroded (all the salt around here). Cleaned both with a wire brush and reassembled and the light went back off.

It could be possible that at this point the shitty reman bolt is falling apart and I might just need a new alternator since that is pressed into the rectifier. I'm gonna take a closer look tomorrow but for now I'm just carrying a 10mm socket with me so I can tighten it and turn the light off.

 

What is underneath the terminal, just the plastic terminal insulator? Is it possible the new alternator didn't come with the outer nut, so you removed the inner nut?

Just look for some videos/tutorials showing how to remove and disassemble the alternator and you should see the nuts.

Here are some snippets from the 96 Toyota Repair Manual, but I believe the alternators are basically the same from all years. The outer nut holds the wire. The inner nut holds the terminal insulator.

GENERATOR REMOVAL
2. REMOVE GENERATOR
(a) Disconnect the generator connector.
(b) Remove the nut, and disconnect the generator wire.
Torque: 9.8 N·m (100 kgf·cm. 7.2 ft·lbf)

GENERATOR DISASSEMBLY
1. REMOVE REAR END COVER
(a) Remove the nut and terminal insulator.


GENERATOR ASSEMBLY
(b) Install the terminal insulator with the nut.
Torque: 4.1 N-m (42 kgf-cm, 36 in-lbf)

 

The nut holds the regulator assembly, brushes etc to the diode pack underneath. The exposed stud is the B+ from the diode pack. The exciter for the field windings comes from the smaller wires connected to the regulator assembly. If it is truly charging some thing is fubared and most likely will return. Because the light is out does not necessarily mean it is charging without a voltage reading.

 

Just bought an OEM alternator off a member here. I’m gonna clean it up and put it on.

How should I go about rebuilding it? Are there things that should be replaced.

 

If it were not charging and just turning the light off I think it would’ve stalled out and died by now, right? I’ve driven about 150 miles this light coming on every other day.

 

I was looking at some parts on rockauto and some of the alternators have two nuts and some don't. Looks like the denso reman one I got only has one nut and a differently designed insulator (?)

 

Only thing to check or replace would be the brush pack. Nice find on the OEM man, way to go.
I've never seen one of our OEM alternators have bad bearings. It happens of course but must be very rare.

 

That could be an indicator that it's charging, yes, especially since battery hasn't died right?

 

My old alternator seized while I was away at school. Not sure what caused it, if the brush holder just deteriorated and jammed it up or if the bearing ran dry or went bad.

Nope never died, and just got a new one last week cause my old one was right on the cusp of testing as "bad"

 

I think you're on track. You got good basic understanding of electrical and the tool and the best online teacher around with Rysiu (he really should put together a web page or something because the graphics he uses are excellent and the info is right, maybe like a Daniel stern kinda thing)

 

Some pictures would help.

The 2003 denso reman picture I see at rockauto shows the nut holding the terminal insulator. There should be another nut holding the cable on. May that's not included because they figure you'll reuse the old nut.

 

I just read the whole thread and I see you called me, so I come like a Genie from Aladdin's lamp . First of all here is the charging diagram of 2003 USA model (no Canadian DRL). It will help me explain possibilities.




So starting from the beginning the charge lamp has nothing to do with anything with alternator itself - charging or not, it is simple output from IC Regulator - the electronic circuit responsible for controlling the voltage produced by Alternator. When alternator is not producing any voltage the contact L will have low voltage making the lamp to go on.

There may be different reasons why alternator is not producing power. Could be the alternator is simple faulty, brushes are not good or ... the "sense" wire is not showing the true voltage.

The IC is reading the voltage between the contact marked as "S" - sense (white thin wire connected to the alternator) and the ground (it is important that alternator is grounded properly). Based on that voltage it controls the current run through rotor (via brushes) - more current, more voltage the alternator produces. So the first thing to check if the voltage at contact S is the same as battery voltage. If that wire is cracked, corroded, or not having a good contact on either side it will throw off the IC logic and IC may not power the rotor thinking the voltage is to high.

Other reason may be that the "B" contact (red thin wire) does not provide enough power to IC (corroded contacts) and then the whole voltage regulator will not work correctly.

So really it is very hard to tell what's wrong. I would clean all contacts (you have rust and that is bad), making sure all connections are solid, then if problem still exists the next guess would be faulty alternator: worn or not contacting brushes, bad IC or internal connection broken or corroded.

 

The alt. max current output is fixed it is by design it is controlled by the amount voltage to the field (the thing spinning inside) The regulator scenes battery voltage then depending on the voltage it supplies voltage to the field via the brushes in relation to the battery voltage. If the voltage is low the regulator jacks up the field voltage and the current climbs. It is highly unlikely it will ever supply enough voltage to reach max output there is logic related to that all though you'll never see 120 amps it will have a better reserve that a 90 amp. 120 amps is a lot of current think welder. Another limiting factor is the #10 wire connected to the alternator it is capable of 30 amps. The light is trying to tell you something voltage is key here, it is what the entire control circuit is. These are tough alternators if you get another one install it don't take it apart your chances are about 80% it will work fine.

 

Will a pre 2000 4cyl alternator fit a 2003? Only difference I can tell is that it is a 70A vs 80A

 

Anyone know the size of that alternator nut or have a link to one on Amazon? I know it’s a 10 mm socket but not sure of the thread size and it has a washer built into it.

Light hasn’t come on since Thursday btw. I torqued it down to about 14 with a torque wrench and it’s holding so far, fingers crossed. I’d still like to get a second nut on there.

 

Doesn't a 10mm nut usuall go with a 6mm x 1.0 bolt thread?

 

Sounds correct. Toyota used JIS sizes which are mostly similar to other international metric standards. That's a 6mm x 1.0mm thread pitch. This is where a thread gauge comes in handy to measure thread diameter and thread pitch.

For some reason I thought the inner nut used a bigger wrench in spite of them both fitting on the same threads, or maybe the inner one just has a bigger built in washer (or flange nut). I don't think it should matter too much. Use whatever fits the threads.

 

It’s been over a week now and the light has stayed off. I tensioned up the squeaky belt yesterday too.

There ya have it, another example of why following torque specs is important. Cause “tight enough” is never good enough.

 

Did you ever figure out what was going on here? Thanks

 

Yeah, that B+ terminal was corroded and kept creating a bad connection. Eventually that stud just snapped from rust about a year after I made this post. Got a junkyard alternator and it’s been fine since. Key point: there’s a little plastic cover on that terminal that was broken on my old alternator and therefore allowed moisture and salt to get onto that stud. Make sure your little plastic cover is in place and you have it loaded up with dielectric grease.