Changed alternator, still not charging.

M

meekie4

New member
Hey guys, my low voltage light has been on on on the dash and my car isn't charging the battery anymore. I swapped in a carquest alternator and that fixed the issue for about a week then the light returned. So then I went to a junkyard and picked up another alternator and again, it worked for a short while and now I'm back again with low voltage light on.

I have the 'big 3' wire upgrade done and I recently went through the grounds that I knew about and cleaned them up. (Fender, frame, and engine bay ground)

The battery is just over 2 years old and my runner is a 1996 3.4

My questions are: does the alternator have a specific ground running off of it? If it does where is it located.
What else could I run through to find what's causing my electrical problem?
And any other advice on the subject is helpful.
Thanks
 
Register to hide this ad
cashmoney said:
Have you checked the voltage with a meter?
Click to expand...

Just tested the battey fully charged.
12.83 volts with the car off
12.13 with the car running

Tested voltage produced at the alternator
19.5 volts from the positive lead.

That shouldn't be that high?
 
If the power at the alt is 19, but 12.13 at the battery there's a broken wire in between the alt and battery
 
Could also be a parasitic drain. Are you able to drive the your 4runner at all without it stalling due to your battery being dead? If so then your alternator is not the issue since it's able to keep up with the charging while driving. If you're coming out in the morning to a dead battery then you have a parasitic drain.
 
The voltage across the battery terminals with car running should be at least 13 volts. As Nelly suggested, it could be high resistance in the wire from the alternator to the battery given you have thrown multiple alternators at the issue. With the car running, check DC voltage with one meter lead on the end of the wire at the alternator and the other lead on the end of the wire at the positive terminal of the battery. If you see more than 0.5V on the meter (ignore the +/- sign), the wire has too much voltage drop and should be replaced.

Buckaroo
 
I looked at the voltage produced at the alternator (19.6v) then at where it connects into the fuse box (11.5v)
I would have never looked at the voltage to the fuse box side if you guys didn't recommend taking a look at that wire. Turns out it was a bad connection/crimp on my wire and got that taken care of. Now I'm at 14.3 v at all connections, no more battery light and I went over all my wire connections. Thanks again you guys for the help.
 
Meekie or Buckaroo, can either of you point out the wires that you are talking about?

My battery light came on after I blew/replaced the TAIL 10A fuse under the dash. There are no other electrical issues. The battery is reading below 12v now, but isn't having trouble starting or running. I am not driving it. So I took the alternator off and had it tested, it passed 3 times at two different part stores. I tried a brand new alternator and it didn't clear the fault.
(the lights for the a/c controls and radio preset buttons were out, that is when I checked and found the blown fuse)

EDIT: I wanted to add that I cannot reprogram the automatic door lock behavior. I run the sequence for lock/vehicle speed and it just unlocks, when it is supposed to unlock/lock/unlock to verify reprogramming. Not sure if the lack of power makes it unable to reprogram.
 
Last edited:
Two wires coming off the alternator. The one carrying the alternator output is the heavier wire of the two. It should run back up to the battery positive lead and, I think goes through a fusible link on the way.

I don't know why your battery light came on after changing the TAIL 10A fuse. Perhaps check the IGN 10A fuse and make sure that it is good/not loose.

Buckaroo
 
RuLost2 said:
Meekie or Buckaroo, can either of you point out the wires that you are talking about?

My battery light came on after I blew/replaced the TAIL 10A fuse under the dash. There are no other electrical issues. The battery is reading below 12v now, but isn't having trouble starting or running. I am not driving it. So I took the alternator off and had it tested, it passed 3 times at two different part stores. I tried a brand new alternator and it didn't clear the fault.
(the lights for the a/c controls and radio preset buttons were out, that is when I checked and found the blown fuse)

EDIT: I wanted to add that I cannot reprogram the automatic door lock behavior. I run the sequence for lock/vehicle speed and it just unlocks, when it is supposed to unlock/lock/unlock to verify reprogramming. Not sure if the lack of power makes it unable to reprogram.
Click to expand...

This is the EWD for an 02, it should give you an idea of the possible bad connections. The Large wire that goes through the 120A fuse can be checked by checking voltage at the alternator with the engine off. It should be whatever the Battery has with the engine off. If not your problem is in that circuit.

Next the two fused ignition circuits, AND the Stator circuit which is also battery voltage.

http://tacoma.site40.net/4Runner_96...pdf/ewdsourc/2002/024runne/systemci/014cs.pdf

:snacker:
 
Thanks everyone. I chased wires for a while and couldn't find anything wrong. I checked again and the battery was 12.5v and alternator was pushing 13.9v with the light still on. So frustrated but not defeated, I checked ALL fuses again, and even though it was "good," I changed the ALT-S fuse... and POW! Light goes out!
Still cannot get the door lock reprogram to accept, but that is trivial to making sure the charging system is good.
Thanks again.
 
RuLost2 said:
Thanks everyone. I chased wires for a while and couldn't find anything wrong. I checked again and the battery was 12.5v and alternator was pushing 13.9v with the light still on. So frustrated but not defeated, I checked ALL fuses again, and even though it was "good," I changed the ALT-S fuse... and POW! Light goes out!
Still cannot get the door lock reprogram to accept, but that is trivial to making sure the charging system is good.
Thanks again.
Click to expand...

Well obviously it wasn't "good". How were you checking it? By the way the Alt-S fuse is the Stator circuit I mentioned in my first post.

:doh:
 
I pulled the fuse and checked it with a multimeter. Correctly. I pulled every single one. I am not a fan of electrics anyway, so I am just glad that the deamon is gone. You called it with the Stator circuit. Thanks.
 
I had an alternator over charge at just over 17 volts and had the batt light come on although this is not your problem I just wanted to throw it out there that over charging will trigger the light as well.
 
I'll jump in, too.

The battery/no charge light is turning on intermittently.

At one time, the battery light turned on, it was a very rainy day and I was out for a 110 mile trip. It was on for the duration of that ride, until I got home.

Now, the battery/no charge light is turning on intermittently. Never on more than 15-20 minutes, and then goes away.
Does that indicate that my alternator is slowly going ?

I did not measure the voltage anywhere besides at the battery, and it was at 13.8V, with some load (lights, fan).

how about the alt' belt - I'm not sure how to check for correct tension. I tried tightening it up, but, the movement of the tightening bolt does not really seem to add any tension to the belt - is there any chance it's the belt tension ? (belt has less than 10K miles in use).

I should be getting the multimeter by mail in a couple of days will be able to run more tests.
 
Last edited:
Lug1 said:
I'll jump in, too.

The battery/no charge light is turning on intermittently.

At one time, the battery light turned on, it was a very rainy day and I was out for a 110 mile trip. It was on for the duration of that ride, until I got home.

Now, the battery/no charge light is turning on intermittently. Never on more than 15-20 minutes, and then goes away.
Does that indicate that my alternator is slowly going ?

I did not measure the voltage anywhere besides at the battery, and it was at 13.8V, with some load (lights, fan).

how about the alt' belt - I'm not sure how to check for correct tension. I tried tightening it up, but, the movement of the tightening bolt does not really seem to add any tension to the belt - is there any chance it's the belt tension ? (belt has less than 10K miles in use).

I should be getting the multimeter by mail in a couple of days will be able to run more tests.
Click to expand...

Was the light on when you measured voltage?

The alternator can have a diode go bad inside, and not turn off the light. There is a circuit just for the light, the L terminal on the alternator connector. It's not easy to do, but if you could check voltage either right at the alt, or at connector EA1 terminal 1. Here is the link to show that connector.

http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/ewdtmc2/ewdtmpdf/ewdsourc/2002/024runne/electric/connecto.pdf

If you have 13.8 or so with the engine running, then the problem is more likely in the light circuit or instrument cluster. If you don't, the problem is in the IC regulator, inside the alternator. If it is still charging well, consider replacing just the regulator as opposed to replacing it with a cheap reman.

:couch2:
 
it's been a months since, but, digging deep into memory - no, the light was not on.
1 day away from getting the multimeter, I'll do as many measurements as needed..(so far I needed to borrow one.. that wasn't serious..)
 
Just would like to chime in on my recent experience. I was having the battery light come on intermittently and finally one day while I was out of town the alternator died on my wife (Murphy's law). Anyways I replaced it about two weeks ago. Well tonight the infamous battery light came back momentarily and then went away. After it went away, I started to get a whining sound at idle as if the alternator was under a load. Got home and put a meter on the battery at idle and got approx. 12.6-12.8v and no change with a load (lights,flashers, heater...)
I think I may have got a "dud" alternator...
Any thoughts???
 
Aircraft Mech said:
Just would like to chime in on my recent experience. I was having the battery light come on intermittently and finally one day while I was out of town the alternator died on my wife (Murphy's law). Anyways I replaced it about two weeks ago. Well tonight the infamous battery light came back momentarily and then went away. After it went away, I started to get a whining sound at idle as if the alternator was under a load. Got home and put a meter on the battery at idle and got approx. 12.6-12.8v and no change with a load (lights,flashers, heater...)
I think I may have got a "dud" alternator...
Any thoughts???
Click to expand...

ouch! Check my posts in this thread starting on the first page, look at the links for the diagrams. Check to make sure the fuses are good, USE A VOLTMETER, or a test light. An alternator is easy to diagnose, just confirm the wiring is ok, and you can be sure it's a dud.

:help:
 
Aircraft Mech said:
Just would like to chime in on my recent experience. I was having the battery light come on intermittently and finally one day while I was out of town the alternator died on my wife (Murphy's law). Anyways I replaced it about two weeks ago. Well tonight the infamous battery light came back momentarily and then went away. After it went away, I started to get a whining sound at idle as if the alternator was under a load. Got home and put a meter on the battery at idle and got approx. 12.6-12.8v and no change with a load (lights,flashers, heater...)
I think I may have got a "dud" alternator...
Any thoughts???
Click to expand...

Lemme guess....auto parts store reman? I hope you didn't core trade a factory Denso for it. Those can be rebuilt.
 
You must log in or register to reply here.

Members online

Total: 160 (members: 1, guests: 159)

Forum statistics

Threads
278,309
Messages
3,554,071
Members
248,016
Latest member
Advally Service

Share this page

Trending content

Back
Top