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And it begins... charging system "74" CJ5

And it begins... charging system "74" CJ5
U

uncoolperson

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Location
Bellingham, WA
Vehicle(s)
74 CJ5, some stuff done to it (I'm sorting it all out)
So, when I bought this it was explained the ignition switch didn't work (had to stall it to kill it)... I'm okay with that, that's something I can and have solved in the past.

After replacing that, it's not that... Tracked it down to the alternator keeps feeding the system, disconnected she starts and dies on command.

Trying to make some sense of my wiring and the schematics I've found for CJ's online, and that hasn't happened yet. Got to thinking, perhaps there's a mod or the schematics aren't right or something that you guys might know about.

So, here it is, my sad paintbrush drawing of my charging system. Any clever ideas?



Thanks
 
in that drawing dist = coil, wire going off to nowhere is going to dist... sorry, was getting late.
 
The wire that goes between the coil and the alternator is the location where a resistor wire or a diode needs to be to stop that backfeeding. If no one can chime in on this I can find some more info on this. A trip to a local auto electrical shop may help also.
 
Here is a link. It's for a FSJ, but the basics are the same.
http://oljeep.com/gw/elec/74/74_FSJ_WiringDiagramPage1.jpg
There should be no connection between the alternator and the coil. The three smaller wires from the alternator should go to the regulator. The large red wire should go to the battery side of the starter solenoid. If what you drew up is what you have, it's really messed up. No way should the regulator be connected to the battery. That is probably why the Jeep won't shut off.
 
Torxhead said:
You haven't messed with wiring at all have you?]
Click to expand...

I draft schematics/design wire routing (not very well tired and in paint), I can read understand the schematic to the actual item... wire up simple relays/switches and lights. But aside from that my electrical understanding is pretty Limited .

Thanks all for the input.
I'll give it a gander, some post sleep thought and not stuck on "why is my voltage jumping to 15 when I yank the key, and what's with this wire doing that?" I've got a path to chase down.
 
Last edited:
Torxhead said:
the alternator is the location where a resistor wire or a diode needs to be to stop that backfeeding.
Click to expand...
Torxhead has it. The engine won't stop becouse the alternator is turning and producing voltage that is getting back fed into the ignition system. You need a diode at the alternator to fix this.
MSD Ignition
 
I've never used a diode. If it's wired per the schematic, a diode isn't needed.
 
Good info. :D
 
so you cut the wire and put the diode in line?
Is the stripe on the diode pointing toward the alternator?
 
This is the small brown wire?
Is the diode still good? Check it with an ohm meter. With the black lead on the end near the stripe it should read 0 ohms. Then reverse the leads so the red lead in near the stripe. You should not get any response from the meter. It should be infinite ohms.
 
csuengr said:
I've never used a diode. If it's wired per the schematic, a diode isn't needed.
Click to expand...


You do either need the diode or the original resistor wire (like Torx and Busa said) otherwise the alternator will feed power back to the switched side of the ignition and the engine just keeps on runnin'...
 

Attachments

So first diode in my two pack was toasted, i had guessed from my expert soldering job (familial tremor makes for fun). Second one was testing good from the package when I installed it, and the jeep shut down correctly, prompting me to come here and shout "yay!".
then, returned to retract that.

apparently, the jeep fried that one.
to be sure, I tried another today. Instant death, like a mosquito in a bug zapper.

I'm using the radioshack p/n 276-1143 as I've seen specified here and elsewhere, (3A, 200V). Will try to locate a beefier diode over the next few days.

Installing this on what I believe is called the exciter wire (the one that isn't positive, or ground, those are my only three choices) that goes from the regulator to the alternator.
 
new voltage regulator, no longer frying diodes... I bet I probably misconnected something.

hooked up as shown here
Alternator won't charge battery/Hacked wiring - JeepForum.com

with the exception being the bat wire off the alt goes into the dash (for the not hooked up ammeter I'm guessing).


Still does not turn off, diode on field wire stripe towards alternator.
appear to have good contacts all around.
 
I think you should check and see if there is still voltage going to the coil after shutoff. If there isn't that would verify that the run circut is shutting off.
 
running key off: 15+ volts
not running key off: 0


I haven't said so, mostly cause I've been in a mood with the jeep when i get to posting here.
Thanks everyone for the responses, and not pointing out how much of a moron I am.
 
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