Alternator troubleshooting questions (2 Viewers)

[88TXCruiser]

I could use a little help troubleshooting my alternator. 1988, 3FE. I noticed that the voltage is not coming up like normal when running. Checked with a voltmeter at the battery terminals, and sure enough the voltage stays around 12 V even when running, and when I rev it up a bit. Fusible links have be redone recently so I think that's probably not the issue, but I'll check on them as well.
Also noticed that the little "battery" light on the instrument panel does not light up when key is in the "on" position. Nor does it come on when the engine is started.
Engine starts and runs fine. checked "charge" and "engine" fuses and they check out OK too.

Checked FSM, and figured I'd start with this -

OK, so "terminal B" is the threaded lug in the upper right in this picture (that should have a boot on it?) ?

Just trying to get this right before I fry something.
Thanks,
marc

 

[FJ60Seth]

Check the voltage at the alternator. The wire from the alt to the battery could be bad.

 

[88TXCruiser]

Check the voltage at the alternator. The wire from the alt to the battery could be bad.

measuring at the big threaded lug? or one of the spade terminals?

 

[FJ60Seth]

I think it’s the big threaded lug. It should end at your battery positive.

 

[88TXCruiser]

Ok. Big threaded lug to ground, before start 0v, engine running, 12v

 

[cruisermatt]

Check the voltage at the alternator. The wire from the alt to the battery could be bad.

This is unlikely. On a 3FE it is multiple heavy heavy gauge wires crimped together with multiple redundancy points.

 

[cruisermatt]

Ok. Big threaded lug to ground, before start 0v, engine running, 12v

If you are only getting 12V your alternator isn’t charging. It should be like 13.4-13.5.

If your wiring all appears to not be tampered with it is likely fine. I would try a fresh alternator first.

@ToyotaMatt has them in stock.

 

[majdomo]

If you are only getting 12V your alternator isn’t charging. It should be like 13.4-13.5.

If your wiring all appears to not be tampered with it is likely fine. I would try a fresh alternator first.

@ToyotaMatt has them in stock.

Was just typing up the same thing. Check voltage at the battery while running for 13.5+. Hit up ToyotaMatt or send your current one out for a rebuild.

 

[ToyotaMatt]

I could use a little help troubleshooting my alternator. 1988, 3FE. I noticed that the voltage is not coming up like normal when running. Checked with a voltmeter at the battery terminals, and sure enough the voltage stays around 12 V even when running, and when I rev it up a bit. Fusible links have be redone recently so I think that's probably not the issue, but I'll check on them as well.
Also noticed that the little "battery" light on the instrument panel does not light up when key is in the "on" position. Nor does it come on when the engine is started.
Engine starts and runs fine. checked "charge" and "engine" fuses and they check out OK too.

Checked FSM, and figured I'd start with this -
View attachment 3346660
OK, so "terminal B" is the threaded lug in the upper right in this picture (that should have a boot on it?) ?
View attachment 3346662
Just trying to get this right before I fry something.
Thanks,
marc

.
- when this above happens above " " ?


- then it is time for this to happen below , along with the little GREEN plug below that too ........

- you do understand that the fact that your DENSO PLUG CODE #280 has been sheared clean off like that , your rectifier board and subsiquent diodes
are now ashes inside that unit ?

- i won't ask how or why here ?

- but running of the reserve capacity of your battery like that will strain the wet cells that you have in your battery ....

OEM Genuine NipponDenso / DENSO Japam Spec. Alternator 90A amps 1988-1992 FJ62 FJ80 3FE 3F Carb - VintageTEqParts.com

NO CORE REQUIRED ! MADE IN JAPAN GENUINE OEM NipponDenso / DENSO Alternator 90A amps MADE IN JAPAN 1988-1992 FJ62 FJ80 3FE ...

vintageteqparts.com

.

 

[88TXCruiser]

more to the story (if anyone is curious at this point) - disconnected the wire on the big threaded lug (assume it is "terminal B" per the FSM), and tested voltage from that lug to ground while running - 60V ! ? and amperage from that lug to the disconnected wire = 0 A. Per the manual that points to "replace the IC regulator".
But maybe that just means, "buy a new alternator" and move on....

 

[88TXCruiser]

View attachment 3346877



.
- when this above happens above " " ?


- then it is time for this to happen below , along with the little GREEN plug below that too ........

- you do understand that the fact that your DENSO PLUG CODE #280 has been sheared clean off like that , your rectifier board and subsiquent diodes
are now ashes inside that unit ?

- i won't ask how or why here ?

- but running of the reserve capacity of your battery like that will strain the wet cells that you have in your battery ....

OEM Genuine NipponDenso / DENSO Japam Spec. Alternator 90A amps 1988-1992 FJ62 FJ80 3FE 3F Carb - VintageTEqParts.com

NO CORE REQUIRED ! MADE IN JAPAN GENUINE OEM NipponDenso / DENSO Alternator 90A amps MADE IN JAPAN 1988-1992 FJ62 FJ80 3FE ...

vintageteqparts.com

.

View attachment 3346880

so if I order the alternator on the website does the green plug and terminal ends come with? or is that a separate item?

 

[ToyotaMatt]

so if I order the alternator on the website does the green plug and terminal ends come with? or is that a separate item?

Everything in the Listing related to the PLUG-Replace-Install-Parts Shown in the BELOW photo

( same PHOTO as the store offering page , just copy and pasted it here )

DO come with the 3FE Alternator as a ALL-Inclusive KIT FORM product , YES ...


i only singled out the GREEN PLUG above , because your ENTIRE Alternator brown input socket has been chopped clean off , so it's logical to conclude its HARNESS Side mating matching DENSO Plug Code # 280 connector is a victim of the same tragic fate there too ...
and wanted to make sure you understood that came with my KIT FORM 3FE Alternator ....

.