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Old 09-07-2017, 05:17 PM
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Default 40 voltage regulator

Hi electric gurus. I have a symptom going on with my 1977 FJ40's electrical system that I could use some expert advice to diagnose. My volts at the battery vary cyclically when the truck is running. Volts read about 12.7 when truck is off. When I turn it on, the reading climbs to 13.6-8, but every two minutes or so it cycles down to 12.7 ish, then back up again. About two minute cycles up and down. When it cycles down, you can hear a load come off, then when it goes up, you can hear the load pull again (slight rpm change). The battery is new, the alternator load tests good at the store. There is also a visible change on the gauge in the dash when this happens...positive to negative and back. I can't find any obvious ground problems. I noticed that my 62 holds steady at 14.2 with no cycling, so i'm wondering if this cycling is normal or indicative of a problem.

It sounded to me like something the voltage regulator might be responsible for so I did the three tests in the FSM for the regulator. All three were where they should be with the points engaged, but did not change when I pushed the arm to disengage the points...and that is not right. Do I need a new regulator?
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Old 09-07-2017, 05:48 PM
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That's what i sounds like to me, I don't think they're super expensive to try, right? $15-$30 at rock auto, napa probably has a nicer one. Mr T will have the nicest, probably worth $20 to toruble shoot it a litter easier.
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Old 09-07-2017, 07:46 PM
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Quote:
Originally Posted by akingf5371 View Post
That's what i sounds like to me, I don't think they're super expensive to try, right? $15-$30 at rock auto, napa probably has a nicer one. Mr T will have the nicest, probably worth $20 to toruble shoot it a litter easier.
I am blanking on the name of the alternator shop off of 38th right now, but they probably have a solid state VR sitting on the shelf. Pretty cheap, and a great upgrade, IMHO.

Dan
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Old 09-07-2017, 08:47 PM
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What does solid state mean?
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Sascha Steinway TLCA # 20217
1977 FJ40 "Ripper" (because it shreds!) (What is a "shread"...Steve Crase)
1988 FJ62 "Dino" OME, my next project
2000 4 Runner, my daughter's truck, thanks Dan!
2013 F-150 "Black Ops"
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Old 09-07-2017, 08:52 PM
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and 38th and what cross street?
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Sascha Steinway TLCA # 20217
1977 FJ40 "Ripper" (because it shreds!) (What is a "shread"...Steve Crase)
1988 FJ62 "Dino" OME, my next project
2000 4 Runner, my daughter's truck, thanks Dan!
2013 F-150 "Black Ops"
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Old 09-07-2017, 09:17 PM
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There's an old school shop on 44th near Tejon called Generator Exchange. 2650 W 44th Ave.
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Old 09-07-2017, 10:05 PM
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Sascha, my understanding is that solid state runs through a circuit board, and resistance is measured through components in the board, rather than coils and resistors usually found in older parts construction.

Solid state should give a more accurate results.


There's an alternator place called A-1 by Commerce City we've used at work. I'll find their card, and post.
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Old 09-08-2017, 03:45 AM
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Quote:
Originally Posted by Crash View Post
There's an old school shop on 44th near Tejon called Generator Exchange. 2650 W 44th Ave.
I was close! This is definitely it. Generator Exchange. I was off on the street. 38th and 44th look about the same in that area though, in my defense!

And a standard VR is operated by a set of vibrating contacts constantly opening and closing to regulate the voltage (the amount of time closed regulates the output voltage), but a solid state VR uses transistors to do the same thing, instead of mechanically vibrating reeds and contacts opening and closing all the time--much more reliable.

Dan
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Old 09-08-2017, 09:53 AM
SteveH SteveH is offline
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In the mid-late 70s, FJ40 voltage regulators used a variety of different plug styles, so beware that just because someone says that it 'fits a '77' doesn't mean it necessarily will.

On Mud, there are discussions of bending the contacts to 'tune' your voltage regulator to work better, or drive a higher voltage. I have never done this. Toyota has discontinued the '78 VR, as far as I know.
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Old 09-08-2017, 10:57 AM
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Yeah, none of the ones available from places like Rockauto have the right plug for my truck. It seems like there is about a year-and-a-half gap that my truck falls into that is about impossible to find. Of course, rumor has it that some guy who lives outside of Dumont knows how to re-wire Toyota plugs at the fitting without splicing so that it looks like a stock application...

But I think Ill go visit Generator Exchange.
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Sascha Steinway TLCA # 20217
1977 FJ40 "Ripper" (because it shreds!) (What is a "shread"...Steve Crase)
1988 FJ62 "Dino" OME, my next project
2000 4 Runner, my daughter's truck, thanks Dan!
2013 F-150 "Black Ops"
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