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If you use search you will find several threads about the alternator however finding a writeup about removal, brush cleaning and reinstall, is a bid more difficult. This has been covered by our famous bandi however his pics are no longer up... (Original thread: http://www.fjcruiserforums.com/forums/how-technical-articles/70967-alternator-fix-battery-light-inst-w-pics.html)
Bandi, as always, thanks!



If you start to notice a voltage drop, slow starting, slow window, dim lights, or hear a noise that sounds kinda like a supercharger on its last leg, your alternator probably is taking a turn for the worse.

- First things first, check your battery, it should be right around 12.5ish while the vehicle is off.

- Next, check your voltage! At idle, or at any RPM, it should be right around 14V.

- Next, check your wiring, make sure your positive and negative terminals are clean and tight. Check your battery ground points and the power cable on the alternator.

- If your worried that your aftermarket stuff might be affecting the system, just simply disconnect it all at the battery and check if the problem goes away.

- Next, stop by a local auto parts store and ask them to do a voltage check. Most, if not all can check your battery and charging system (alternator) in matter of minutes.

If all signs point to bad alternator... well its a bad alternator.

However, before you go out and spent the money on an alternator, check to make sure your brushes are making a clean contact. If you have done a lot of mudding, you've got a 50/50 shot of fixing the problem for free!


Time:
Depending on how much stuff you got connected to your battery and how many (if any) of the bolts on the alternator are seized. Changing an alternator should only take you about 30 minutes. Cleaning the alternator and cleaning the brushes should only take about 20 minutes.

Tools:
What ever tools you need to disconnect the battery, may vary depending on your setup.
-10mm Deep-socket
-10mm Wrench
-14mm Short-socket
-14mm Deep-socket
-8mm Short-socket
-Couple of extensions
-Braker Bar
-Flat Head Screwdriver
-Filips Head Screwdriver
-Paperclip

You will also need:
-Brake Clean
-Electrical Cleaner
-WD40
-Compressed Air
Or a new alternator...

What to do:
1. Disconnect the battery, negative first, then positive. If you are running a secondary battery or capacitors, make sure those are isolated and won't cause a spark if the positive terminal accidentally hits ground.

2. Remove the battery bracket (tie down), remove battery and battery tray.



3. Remove the 2 brackets that hold the battery wiring harness in place. This is done with 3 10mm bolts. Two of which can be reached from the top:


The other will need to be reached through the driver side fender wheel. Depending on how old your FJ is, you might still have the dust protectors in place, you might not. Use a flathead screwdriver to remove the clips on order to gain access. OR, you could try to get at it from the back of the alternator with a 10mm wrench. Here is a picture of the third 10mm that needs to be reached:


4. Remove the alternator power protection bracket (10mm):


5. Disconnect the electrical connections on the alternator. One will be a regular 4 prong plug, just simply press the release button. The other will be the main power wire. Remove the plastic clip with a flathead screwdriver. Just simply place it in one of the 4 openings and gently pry away from the wire, it should pop off with no problems. Then undo the connection with a 10mm:


6. Losen the belt and remove the belt from the alternator with a 14mm and a barker bar:


7. Remove the two 14mm bolts that hold the alternator in place. These will most likely need some convincing to break free. DW40 might not be a bad idea here:


8. Make sure to pull 'UP' on the alternator, not forward, the lower bracket is a U adapter, see here:



Now if your just replacing the alternator, follow the steps in revers order and your done! IF, you are trying to 'safe' the alternator, follow the next couple of steps.

9. Remove the 3 8mm nuts on the back of the housing:


10. Remove the two fillips screws on the brush housing:


11. Here is the brush housing.Feel the brushes and see if they spring back. Most likely they won't:


12. In order to clean it you will need to remove the yellowish plastic cover. This is done by prying outward with your finger, you will notice that the bottom (opening) will slightly move, at that point, use a screwdriver on the release hole on the top (just turn it around you will see what I mean). It should pop right out:


13. At this point use brake clean, then compressed air, then electrical clean, then compressed air to clean the brushes, brush housing and alternator as best as you can. Now feel the brushes, they should spring back much better now. Picture of a clean brush housing:


Pictures of a 'clean' alternator:



14. In order to reinstall the brush pack, you will need to hold the brushes back. You can do this with a paperclip through the top clip hole:



15. Reinstall cover and follow steps 8 through 1 in reverse. With any luck, your voltage will be back to 14V. Keep an eye on it for a couple of days just to make sure. If it didn't work. Time for a new alternator...


For me, it was time for a new alternator at 110,000miles...

 

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very nice writeup dan! now that im almost at 100k, ill probably be needing this fairly soon
 

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Mudded and my battery light came on. Truck ran fine but lights went weird. Pulled over after an hour. Turned the truck off, wouldn't start. Put in my backup battery and drove home one hour. Battery light stayed on. Washed engine out w water. No change. Bandi's writeup was great but pics died so this post was awesome. Took my nonmechanic self 2hrs. Didn't have to remove my Bud Built armor. Getting the alternator back in was the toughest part. Had to tap it in. I used a survival mirror to align the two large bolts. A total PITA. I held the tensioner pulley breaker bar in place w string run to the passenger wheel well instead of using the allen wrench through the hole thing bc it was too tough to deal with. Got brake cleaner in my eye, forgot to wear glasses. Note to others. Stock pulleys sound fine. Ordered sealed ones anyway for later from RockAuto. Belt was good at 50,000. I think the fan flings the mud everywhere. The mud was 12 inches deep and a splash not sitting in 3 feet of mud. Read in Land Rover posts they shut the fan off when crossing water and mud. Then restart when out. Not sure how to do this. The water cools the engine. Doing this may help us all out avoiding the mess in the engine bay. Anyone hear of this or know how to temporarily cut the fan? They also drain the four oils after each water crossing but I'm installing 4 snorkels for that. Thanks everyone for this invaluable resource. Cheers :cheers:
 

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Pumbaa to the rescue again! This thread was perfect, saved me getting a new alternator.

The little brush things in mine were totally depressed - cleaned it out, re-installed and it works great.

Many thanks! :D
 

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My rig is doing the exact same thing. Barely got home tonight before the engine almost cut out on me. Randomly loosing power to your headlights while driving will keep you on your toes! I am going to take my alternator out tomorrow and see if I can clean it. Hopefully that's all it needs. Thanks for the great write up on this. Its amazing the amount of money one can save by just trying to do these sort of things themselves. If I were to take it to a mechanic I am sure they would charge at least 300 bones to do this small job. Again thanks for the write up!!
 

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So i got it apart and then the damn brush assembly busted when i was trying to get it apart. But I'm worried because the brushes looked totally fine and seemed very bouncy... any ideas?

Sent from AutoGuide.com Free App
 

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Too bad we couldn't just spray a whole bunch of electrical contact cleaner on it while it is still installed! :lol:
 

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Thank you very much for your post. this morning I was greeted with the little red battery light on my dash, I went and installed a new battery hoping that would take care of it as the battery in it was the original Panasonic from 07 so I'm sure it was time for it to go but that didn't take care of it. After pricing on installed alternator from Pep Boys at $480.00 I drove home determined to take care of it myself. A replacement alternator was purchased from O'Rileys for $145.00. Didn't have any problems until I was trying to remove the old one, I had the bolts out but it just wouldn't come out. Did a quick search and found your post, and Pull up! That did it! Thanks for your help. Saved me $300 bucks!:grin
 

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Thanks for the instructions and pics! Made it very easy. Still took me a couple hours because I dropped a bolt in the unreachable areas of the body armor, and then a socket...
 

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8. Make sure to pull 'UP' on the alternator, not forward, the lower bracket is a U adapter, see here:



Now if your just replacing the alternator, follow the steps in revers order and your done! IF, you are trying to 'safe' the alternator, follow the next couple of steps.

Nice write up Dan, very easy to follow, I installed a rebuilt one from O'Reilly's but had a hell of a time getting the double sided bolt hole bracket to slide over the thru hole piece,( shown circled in top picture)
I finally took some calipers to measure the inside space between the two holes , the back one being the threaded steel insert ( see bottom pic ) and lo and behold the rebuilt one was about .008" tighter than the one I took out, no wonder it wouldn't slip over, so I installed the bolt, note the back piece that is threaded on the alternator is steel that is sleeved into the aluminum housing, anyway install bolt all the way, then backed it off one turn so there was a little slop under the washer and gave it a whack to push that bushing back a little, it took about 4 or 5 whacks and then it moved back to the space was about .005" more than the original. I went to put it in and it slid right over. As I was doing this I wondered if I would damage the diodes or ??, but she started right up and was putting out 14 volts of charge. My rebuilt unit looked like it was branded new, ie degreased, bead blasted ?? I wonder if that space is one of the checks they do during the overhaul ?? Whatever I pushed it back, I'm sure when I torqued it in place there was ample opportunity for it to slide forward and snug itself , but I'm not taking it out to check ;-).
 

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Hi! So I just got my 07 FJ two months ago (101,000 miles) and this is my first time posting. I started noticing that cursed "supercharger" whining/whirring noise coming from the engine, in sync with acceleration. Took in to Toyota and they confirmed that my alternator is going bad. Voltammeter indicates that it is still producing sufficient charge and the batter light has not come on, though there is a slight hesitation when I start the car.

With the noises and symptoms I've described is there a chance that the brush cleaning could fix me up? Or does it sound like I may be past that stage? Whatever the case, I'd like to try to fix this myself as I am broke as a joke lol.

Great post and great thread! Thanks! >:D
 

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Excellent write up and accompanying Picts - so many thanks!

What a bear it was to get the bottom bolt holes lined up, see yellow circle in Fig 7. No easy way to do it although I used a punch to get me in the general vicinity.

I changed the serpentine belt while I was at it. The best way is to remove the front skid plate using a 10mm socket , using a 14mm, or 9/16" wrench and a 3-4" nail. Laying on your back underneath the belt use the 14mm or 9/16" wrench to load up the tensioner pulley then slip the nail into the holding holes, route the belt, then again using your wrench, load up the tensioner enough to remove the nail from the holding holes. You're home free.

Again - thanks for the help!!!
 
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