first have your battery load tested, to see if the batt is good. If it checks out then take your alternator out and have that tested, but it is most likely your battery is bad. and a nother thing clean off tour battery terminals if you have dirt on your battery, you could be shorting or drain the battery. Or rust on your cables can cause you to just have a bad conection to the battery. Club soda or Diet Coke is a good cleaner for battery's, remove the cables when you clean so that you can get the terminals compleatly

 

im saying the alternator is bad. if it was good, you would be pulling at least 12v while driving. check the belt, wires, and possibly the gorunds to make sure everything is secure. but murphys law will point to the alternator

 

Not sure how much offroading your FJ has seen but somewhere on here there is a post about cleaning an FJ alternator and getting it running like new again.

 

Battery load is good....so it must be the alternator. Im going to see if it is possible to get it rebuilt to save a little money but some people on the forum say they cant be rebuilt. I cant believe that its already possible that the alternator is bad. It has 48000 miles on it, and I have 4 lights up top, 2 in front and back, but I almost never turn them on (they've only been on since January)....I have a amp/sub but I dont bump or whatever.....so iunno.

 

From what you described, it sounds like you were running off the battery since the volts were dropping the longer you were driving and the engine performance was directly affected by the flashers coming on & off.

Sounds like you just need to replace the diodes (a.k.a voltage regulator) that control the alternator or replace the brushes.

You can do it yourself if you are handy, it's highly unlikely the alt. is completely shot.

Bandi shows how to do it here. http://www.fjcruiserforums.com/foru...forums/engine-performance/70947-battery-light-possible-fix-your-alternator.html

DEWFPO

 

You mentioned you have a scangauge. Did you check to see if any codes were set. My guess is it's the alternator as per what DEWFRO mentions above on falling voltage.

 

No codes, just the symbol that the says take to dealership immediately. Check engine light never came on though. I did get the alternator out today....wasnt bad at all. Just some tight screws...just a little more difficult for me since my hands are huge to manuver...but its out. Of course I was going to take it to Oreilly's to get it tested, and of course they cant do it. Cant order it and cant test it.......worthless...haha. Yeah thanks DEWFPO, that is the thread that I used to take it out... I am going to give that a try tomorrow on taking the cover off and such...how do I replace the brushes though if it comes to that. Havent done that one before but I am a pretty handy guy...so I think I could do it with some insight!

 

how do I replace the brushes though if it comes to that. Havent done that one before but I am a pretty handy guy...so I think I could do it with some insight!

That same thread shows the brush pack that Bandi cleaned/replaced. It's the brown plastic piece in the center of the rear of the alternator.

DEWFPO

 

Well, it wasnt that. The brushes were moving freely so iunno from here, going to take it by the alternator shop in the morning and hopefully they will be able to rebuild it!

 

Took my alternator to go get it tested and they said it read "GOOD." They cleaned it up and such and gave it back to me. So I dont know...i dont think its a wiring thing....I guess im just going to put it back in and if it doesnt charge again I'll just order one of the internet....
Anybody else have any suggestions!

 

Just put the alternator back in, and nothing. Volts keep on dropping, and when I take the ground of the battery it dies....so I suppose im going to order another alternator....looked at the wires and still dont think its wires....Any suggestions?

 

anyone?!?!?

 

What your saying is..... you have a good alternator (tested) and a good battery (load tested), but the alternator is still not charging your battery when hooked up and running.

I would not buy another alternator until you find the problem.

I'd hook up your battery thru a DVOM and see what kind of draw you have on the battery with everything turned off (including the engine). If you have a big draw, start pulling fuses, relays, one by one until you eliminate the draw. If the draw is very,very small (milliamps); then......I'd be looking at the wires, fusible links, fuses, loose connections on the : big cables, charging wire, grounds, etc.....

If you don't want to do this, take the FJ to an "Auto Electric" shop. It will be worth the money to have them diagnose the real problem, they do this for a living and are VERY good at it.

DEWFPO

 

I think you're on the right track. When it's all hooked up put a multimeter across the different points and see what the voltage is reading. That should give you an idea of where the problem is.

 

still looking like a bad alternator....the only other thing is if there is a loose wire on the charging system.. check the wires on the positive side of the battery, especially around the wires to the amp you have. sometimes the wire can ground out where it comes into the firewall from rubbing on the sharp metal. are all of your electrical systems still functioning properly? flickering? If not the amp, follow the wires to the alternator and look for the same thing..... loose wires, grounding out, and such. like i said, you are not producing a charge. its either a bad alternator (which tested good????) or a loose/ grounded power wire. may even be as simple as corroded/ loose battery terminal. thats all i got.

 

Today I tested the voltage of the alternator with a voltmeter. It read 11.4. Reved it up and it didnt do anything.....so I'm still going with the alternator....anybody disagree?

Thanks guys
JMC

 

Only assuming there's no huge draw on the electrical system as we discussed earlier.

You had it tested, and it tested fine on a bench outside of the vehicle. That would lead me to think there's a huge draw somewhere on your FJ.

Think of it as a hole in a pipe, no matter how hard the pump (alternator) pumps, it can't pump more than the hole in the pipe is letting out. Think of the hole in the pipe as a ground or huge amperage draw.

If the above is not the case, and the alternator is only putting of 11.4 volts, regardless of rpm, then yes, the voltage regulator (diodes) are probably shot. You can replace the entire alternator ($$$), or just have the diodes ($) replaced. Your choice.

DEWFPO

 

I sure thank you DEWFPO for your help. Just ordered a used one of the internet pretty cheap, with a good warranty in case it dies in the time I own it. We have 2 really good alternator shops in town and neither of them can get parts to rebuild that darn thing. Should be here Friday so I can put it in this wknd! I'll let yal know what happens after its installed.

 

Well its not the alternator. got the new one put on and did no good. Took out my remote start and unhooked my amp just for hope and it also did not good...so does anybody have anymore suggestions? Is there something that controls turn signals, voltage output, and possibly transmission....im now worried its the ECU.

 

Tested for a parasitic draw and I show to have one...and i narrowed it down to the engine fuse block. Bad thing is, i have taken out every fuse except the alt and the heater one because they just plain wont come out. I think they have a screw under the block to release the,..has anybody tried to take them out, or does anybody know how how to get into the engine fuse block?

 

How do you test for a parasitic draw? Just wondering for future reference.

Thanks and did you find out the solution to your problem?

 

It still seems like you have either a wire, fuse or fusable link blown. Is taking it to Toyota an option? Sometimes there are little gremlins in systems that they have the tricks for. A specific circuit that is hard to locate. Because of the fact you are getting no change in the voltage when you rev it up. It sounds like the alternator or regulator isn't getting the trigger it needs to engage at all. Did you get the new alternator tested that you bought from the internet? I know thats a stretch but it would rule out the obvious.

 

Sorry to revive this very old thread, but did you ever figure out the problem? Has anyone else encountered this issue? The exact same thing happened to me today and I am stumped! The truck is less than a year old so I'm calling the dealership Monday to come get the Fj but it would be nice to know what to expect. Otherwise I'll report back.

Thanks.

Edit: Wanted to add other symptoms just for the record. No AC, no compass/temp/inclinometer, no backup cam, no reverse lights, no blinkers, battery slowly dies while working, instrument cluster and radio went crazy... all fuses fine.

Edit 2: Will the addition of driving lights, rear lights, amp/subwoofer, and cig lighter in cargo area void warranty? Each has a fuse, a switch and an add-a-circuit to the fuse block. Also, I cut the door chime wire. Am I in trouble?

Thanks again.

 

FJ towed this morning. Waiting for call from dealership with final verdict on the issue. Spoke with some workers their and they said it sounded like a fried ECU... on an 8 month old truck?!?

Will keep posting.

 

So final verdict for future reference for some other unlucky soul... turns out the alternator and the battery were both dead. They replaced the alternator as it wasn't charging and then proceeded to change the battery since it wasn't holding charge from the new alternator. The alternator suffered some internal damage from a factory flaw... go figure.

For now its all good again.

:clap::rocker:

 

I'm having a similar problem with my 2007 FJ. I was driving the other day and all my warning lights started flashing and my speedo was bouncing. I took it to autozone and they said the alternator wasn't charging the battery.
After fitting a new alternator and recharging the battery, it started not problem. I let it sit for a couple of days, then it wouldn't start. I now have bought a new battery and fitted it.
It started fine again, but almost straight away the warning lights turned on again!!?? I've pulled out all the fuses and can't see a grounded wire anywhere. Has anyone had issues with the ECU?
Thanks