Excellent Wiring Info-Site (Regulator, alternator,...)

Pin_Head

Pin_Head

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[quote author=Brog link=board=1;threadid=10137;start=msg90403#msg90403 date=1074110573]
Just ran across this site trying to rewire my 40 and it has a great tech section, especially regarding our famous voltage regulator.
Brog



http://www.madelectrical.com/electrical-tech.shtml
[/quote]


Some of it was quite good, but the article on bypassing your amp meter in your Chrysler was lame. They made it sound like amp meters were just old technology with no value and they didn't state the main reason why you don't want to run all the current through your dash meter and then back out to the battery (fires!). If they had rewired it like the '78 and up FJ40 with an external shunt, they could have kept the amp meter and had a more reliable wiring system.
 
sherwood

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Yes, I like having an ammeter, as far as knowing what's going on with the charging circuit.

He's correct about the danger of passing the entire current draw back through the cab. It (possibly) coud make an ash-heap out of your cruiser.

You WOULD have to swap out the ammeter itself if you put the 78+ meter in an older rig. IIRC, those ammeters are dwindling in the stock piles... and pricey if you can't find a (non-rusted-stuck) used one. I think CCOT has them on sale for ~$60

I think that maybe the "hot rodders" that MAD Electrical deals with are less concerned about having an ammeter..... and the "wire with a light bulb" is much easier for them to contemplate and install.... and much cheaper.

However..... I'm with you on the ammeter. And, having both the ammeter and the idiot light would be excellent IMHO.

John Sherwood '79 FJ40
Charlotte, NC TLCA Upstate Cruisers
 
Landpimp

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Personly the 79+ amp meters don't impress me, neither of the amp meters work in the 82 fj40s(they are 50amp BTW), it's not the fuses(underhood) I can't count how many 79-83 I have seen with amp meter that don't work. Pisses me off, on both of the 82's the meter is the only thing that doesn't work, I would buy a new one if I thought it would last.........

anyone have a 79+ with a working amp meter?
 
Romer

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Thats a great site. I'll have to look and see if all the current is being fed from that same point. Maybe I'll come up with another idea.

Ken
 
Pin_Head

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[quote author=Landpimp link=board=1;threadid=10137;start=msg90672#msg90672 date=1074134056]
Personly the 79+ amp meters don't impress me, neither of the amp meters work in the 82 fj40s(they are 50amp BTW), it's not the fuses(underhood) I can't count how many 79-83 I have seen with amp meter that don't work. Pisses me off, on both of the 82's the meter is the only thing that doesn't work, I would buy a new one if I thought it would last.........

anyone have a 79+ with a working amp meter?
[/quote]

I haven't noticed any that didn't work, but I own a '76 myself. There isn't that much to the circuit. The meter itself is fused, so it is not likely to be burned out. You can check it by putting a AA battery in series with one of the fuses and seeing if the meter deflects. It does require the stock fusible link, which also serves as an external shunt. If someone just replace the OEM fusible link with a piece of wire it won't work as designed because the wirre does not have enough resistance.
 
Landpimp

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[quote author=Pin_Head link=board=1;threadid=10137;start=msg90881#msg90881 date=1074149052]
I haven't noticed any that didn't work, but I own a '76 myself. There isn't that much to the circuit. The meter itself is fused, so it is not likely to be burned out. You can check it by putting a AA battery in series with one of the fuses and seeing if the meter deflects. It does require the stock fusible link, which also serves as an external shunt. If someone just replace the OEM fusible link with a piece of wire it won't work as designed because the wirre does not have enough resistance.
[/quote]

not following you on the AA battery? I would love to test the guage.

But on the green 82 I had to replace the fusible links, using new NAPA link wire as the OEM link is not availible anymore, it didn't work before..........didn't work after. other 82 has the OEM link still.....but guage no workie
 
Pin_Head

Pin_Head

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[quote author=Landpimp link=board=1;threadid=10137;start=msg90968#msg90968 date=1074302522]
not following you on the AA battery? I would love to test the guage.

But on the green 82 I had to replace the fusible links, using new NAPA link wire as the OEM link is not availible anymore, it didn't work before..........didn't work after. other 82 has the OEM link still.....but guage no workie
[/quote]

The '79 (78?) gauges are low current devices (good idea not running 50 amps into the dash and back) because they use the fusible link as an external shunt (as opposed to integral internal shunt on 78 and older meters). A shunt is basically a low ohm, high current resistor in parallel with the resistance of the meter itself. If the shunt is 1/1000 of the resistance of the meter, the shunt carries 1000 times more current than the meter. If the resistance of the shunt is too low, the meter won't read properly. If the resistance is too high (eg corroded connection) the fuses will blow. External shunt amp meters are also commonly found in marine applications to avoid fire hazards.

To test the meter, run some current through it: Put a flashlight battery (C or D cell will work as well as an AA) in the circuit (eg replace 1 fuse with the battery and check the meter for deflection. Reverse the battery to check the other direction.

BTW, amp meters are often mistaken as not working because they normally read zero when the battery is charged and the alternator is working (but you already knew that, right?) Turn the headlights on and you should see a momentary deflection.
 

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