alternator question (1 Viewer)

[No. 3]

Before I dig in to it I bet there is (as there always is) good advice here. This is what's going on: This afternoon after driving back from the beach I went out for an errand and the battery lamp, the brake lamp and the filter light have all remained on andthe charge needle reeds a hair past 24v instead of the ordinary 28v that it should while driving, this all after having restarted the truck. Obviously the 24v condition is why the lamps are remaining on as they aren't getting the 28v signal that usually shuts them off.

My suspicion is of course the alternator, I'd had it rebuilt maybe five years ago and it has been no trouble whatsoever. I also have a secondary battery system that is maintained by a switching isolator from the alternator shunting power to the 24v truck batteries or the 12v house system as is necessary. Except for this being another variable to consider it isn't raising any flags for me.

For those of you who have faced alternator troubles does my situation turn on any light bulbs? Tomorrow I'll throw a multimeter on the alternator to see what it's putting out exactly. It seems like too recently after a rebuild for the brushes to have worn to the point of needing replacing. So I throw it out to the wisdom of Mudd, thanks in advance!
J

 

[bj40green]

First question.... what year (add to your signature line please)?
Second question..... internal or external Voltage Regulator?
Hook up voltmeter to the +B terminal on the alternator. When revving up the engine you should have 28V.
If OK, check voltage on the +B Battery. If not OK check Fusible Link.
If not.... maybe the VR is the culprit. Check if there is voltage on the IGN wire on the VR. This voltage comes from the IGN key. If not.... check fuse.

Rudi

 

[No. 3]

Oops, it's an '87 which i think I recall is the internal regulator. Thanks Rudi, I'll check the lot- I'd gone through all those tests (I have a shop manual) back when the alternator was failing years ago. Looks like I'm back at them!
J

 

[No. 3]

Update as of this morning- this is the IC regulated 24v alternator and it seems to be putting out only 23.9v at 1800 rpm or so (I don't recall exactly what the RPMs were that's just my sonic recollection, regardless, at that RPM it ought be generating 23-24v.) My guess is that the IC regulator is bad. Am I on to something? Is this an easy to replace part (not like the older outboard ones I know), easy to obtain? Am I driving to Mudrak in Sonoma for the part this week and putting the batteries on chargers overnight to keep them up? Crap, not the worst time but never the best time! It has worked so well lately! The perils of age I guess, just like my arthritis! Thanks again!
J

 

[No. 3]

Hey, the new forum software lets me say, "Crap". Crap crap crap!

 

[bj40green]

If all works fine the output should be around 28V.
The VR is easy to replace. It's under the square/rectangular lid on the alternator.
My EPC tells me for a '87 HJ60 European Market: Regulator assy, 24V, IC type: #27700-57050
Availability.... I don't know.

Rudi

 

[CruisinWithDogs]

I've had similar issues with my 24v cruiser. The Brake, charge and filter lights would go on and off randomly

I had the alternator rebuilt and swapped the regulator, check all connections, grounds, batteries etc.

one day when I slammed the door and all the lights when out, i found the charge lamp relay in the driver side kick panel to be faulty, i would just kick at the panel and then everything was back to normal, lights go off, voltage back to normal.
I got the part from toyota and had no problems since

Part # 27790-57010

 

[No. 3]

I like the kicking story Mr. Dogs- I was broken into yesterday in addition to this, the crappers punched the lock on the passenger door. There's a lot of kicking I'd like to do. I'll check that in the morning with some gentle kicking. And failing that I'll see about finding a new regulator, thanks Rudi for the encouraging news that it's not even a single banana job. I don't have the time right now to take the alt out & have it rebuilt. My truck is a daily driver and this is going to be a week that will have a lot of driving in it. Thanks again! (I'll let you know what the cure is so that any lingering curiosity you folks have is met and so that anyone searching the thread in the future has the whole picture.)
J

 

[No. 3]

Rudi, changed the signature to reflect the year of the truck- it looks as if when I set things up I mistook "Personal Details" for the place to add that. I am not always on top of the internet. Thanks!