FZJ80 Alternator Help

Joined
Mar 7, 2017
Messages
8
Location
Bellingham, WA
Hey all,
I've been reading the forums on this site for a while now, but this is my first post. I'm a complete noob to owning 2 FJ80s, and I need some help. For the backstory, see below. To jump ahead to my issue, scroll to the paragraph that starts: "Then I realized I made a mistake."

I recently purchased a 1991 FJ80 and a 1994 FZJ80 from a friend for cheap who was moving out of town and needed to get rid of them. I was aware that they both needed work, but how much was not clear. I realize that this was a risky choice, but the price was right and I had the cash. My first move was to take them both to a reputable shop to get an accurate list of what they both need. I will post more details about both rigs and will get them on the registry once I have the time to take photos.

The '94 FZJ80 was in good enough shape that it would run, but the shop I took it to for diagnostics told me it needed a new battery. I found this odd, because *I think* the battery had been replaced not that long ago. But, since a battery was the only thing it needed to start, run, and drive off their lot, I gave them the go-ahead to install a new one.

Then I realized I made a mistake. For the past two weeks or so I've been driving the truck around on occasion, and haven't noticed any issues. Until today. This morning, she started up fine. Drove fine for about a mile, then I noticed the windshield wipers were strangely slow. Then some dash lights came on, like the e-brake light, even though it wasn't engaged. A mile or so later, it seemed like we were in a system-wide shutdown: anything electrical was not getting enough juice. Worried that the spark plugs could stop firing, I quickly turned back home and was able to park outside my house. Before I switched her off, I popped the hood - no smoke, nothing irregular. Turned the ignition off, took a different car to run errands. Came back a few hours later, tried to start it, and now it won't turn over.

So before going any farther, I see two possibilities: either something killed the battery without me noticing, or the alternator is bad and needs to be replaced.

Can anyone give me some guidance on this? Am I correct in assuming that this is all the result of a bad alternator? Should I jump start the truck and test the alternator? Once we sort that out I'll be hitting up the vendor forums to look for replacement parts...

Thank you in advance!
 
Joined
Jul 15, 2013
Messages
250
Location
Lakewood, CO
If the battery was to blame you would have still had power to everything while the truck was running. Odds are you wont be able to jump start your truck and keep it going with a dead battery and no working alternator. You could charge your battery and limp it somewhere if you had to. You should try replacing the brushes on your alternator. Its like $20 for the Toyota brushes and it is easy to install once the alternator is out. I wouldnt replace your alternator with a cheap autozone unit no matter what the warranty or price....odds are you just need brushes...
 
Joined
Nov 9, 2012
Messages
6,660
Location
Olathe, KS, USA
Could be a bad battery and or a bad alternator.

I just had a brand new bad battery in mine.

Charge it fully, let it sit for an hour to stabilize, then measure voltage. It MUST be 12.5 V or higher to be considered good.

My other new battery would peak at 12.28V but it would die if I didn't drive the truck within 40 hours otherwise it was dead as a rock.

Good luck!
 
Joined
Jan 5, 2017
Messages
2,261
Location
Charlotte, North Carolina
If you're going to do your own maintenance, you need your own tools. Since your first problem is electrical, I'd suggest your first tool should be a multimeter, not a volt meter or continuity tester. As with all tools, buy the best you can afford. Always.

That said, you should have a Factory Service Manual, either paper of pdf (https://techinfo.toyota.com/techInfoPortal/appmanager/t3/ti?_nfpb=true&_pageLabel=ti_home_page&contextType=external&username=string&password=sercure_string&challenge_url=https://techinfo.toyota.com/techInfoPortal/login/techinfo&request_id=1022933381890309685&authn_try_count=0&locale=en_US&resource_url=https%3A%2F%2Ftechinfo.toyota.com%2Ft3Portal%2Fappmanager%2Ft3%2Fti%3F_nfpb%3Dtrue%26_pageLabel%3Dlib_repair_sum). It will tell you:
upload_2017-3-12_9-15-3.png


upload_2017-3-12_9-15-34.png


upload_2017-3-12_9-16-22.png
 
Joined
Jan 5, 2017
Messages
2,261
Location
Charlotte, North Carolina
So, if, after you finish all that, you decide to tear into the alternator (which Mr. T cleverly refers to as the "Generator" in the FSM):
upload_2017-3-12_9-19-7.png


upload_2017-3-12_9-19-28.png


upload_2017-3-12_9-19-54.png


upload_2017-3-12_9-20-48.png
(I use the "calibrated finger" tool)

upload_2017-3-12_9-21-20.png


So, there you go.

HTH
 
Joined
Mar 7, 2017
Messages
8
Location
Bellingham, WA
Hey guys--thanks so much for the help. With the help of a friend, I installed a reman OEM alternator and we're back online.

One thing I have noticed that I don't remember seeing before: now when I first start the truck, and leave it idling, my rpms will rise and then dip repeatedly. I'm guessing that it'll go down to ~850 at its lowest and ~1500 at its highest. Any thoughts? I'm happy to post that question in another thread if that makes more sense.

Thanks!
 

flintknapper

SILVER Star
 
Joined
May 22, 2004
Messages
5,769
Location
Deep East Texas
Hey guys--thanks so much for the help. With the help of a friend, I installed a reman OEM alternator and we're back online.

One thing I have noticed that I don't remember seeing before: now when I first start the truck, and leave it idling, my rpms will rise and then dip repeatedly. I'm guessing that it'll go down to ~850 at its lowest and ~1500 at its highest. Any thoughts? I'm happy to post that question in another thread if that makes more sense.

Thanks!

Anytime you disconnect the battery....your vehicle will need to relearn its idle. How long has this been doing it?

Any number of things can cause a wandering idle: TPS, IAC, Dirty Intake, Vacuum leaks, etc...
 
Joined
Feb 10, 2019
Messages
2
Location
Sydney
Hey, had similar issue and got a new alternator. However, I am having issues installing it - has anyone else had similar issues? The mount leg is 58mm but the bracket is only 57mm. Should that bushing move 1mm further out (it is flush with the outside of the bracket)? Had a cheap alternator in it, but am replacing with a denso unit if it makes a difference.
Cheers

20190211_135506.jpg


20190211_135420.jpg
 
Joined
Jul 20, 2004
Messages
24,059
Location
Chandler, AZ
The sleeve in the mount (shown in the first pic) moves. I use a socket and bolt as a press, to push it out flush with the inside of the mount. When the alternator is installed, the pivot bolt is properly torqued, it will move back where needed.
 
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