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what ignition circuits do you have to know ?

872 views 11 replies 6 participants last post by  BagusJeep 
#1 ·
Hey everybody, I looked a my wiring harness under the hood and traced all the wires and drew them out. After that I was able to omit the wires that were unnecessary for just starting , charging, and running. Now that I have narrowed it down there are only 3 wires coming out of the bulk head connector in the under hood section, that are necessary for starting , charging, running. 2 blue wire s which are joined in one terminal coming out of the fire wall and a big red wire( I can't remember if it's the big red wire with tracer or solid red at the moment).
Now the blue wires come out as 1 to the under dash portion of the harness and run straight to
the ignition switch. The ignition switch has 6 wires coming out of it and each of them come out and have branches. Do I have to learn these branches to understand the starting charging, and running. Or can I figure everything pertaining to starting, running, and charging, just by looking at my simplified under hood wiring drawing and the red and blue wiring running to the switch , and just the switch itself ?
 
#9 ·
Okay so when the switch is on and or cranking does it connect the red and blue wires which are running from the switch to the solenoid in the picture ?
 
#8 ·
I guess I'm basically asking about the 1 red wire I referred to ,- where does it go under the dash and whatever it goes to is bound to have wires coming out of that and so do I I have to understand that part of the circuit as well ?
 
#10 ·
Thanks John.
1.So john when the switch is on and or cranking does it connect the red and blue wires which are running from the switch to the solenoid in the 2nd picture ?
2. The red wire that runs to the I terminal on the solenoid- it may branch off but all you need to know is it connects the ignition switch ?
3. Are all these pictures just lie the Jeep cj ?
4. So since the 1st picture for ignition doesn't show how the red wire branches off to the alternator is it safe to say the alt. isnt necessary for starting as long as the battery has 12 volts ?

Thanks everybody this looks good. I'm just seeing if I can wrap my head around this starting and charging stuff because last time I remember asking somebody about it got pretty complicated trying to tell which part was bad with out having auto zone test it.
 
#11 ·
1. When cranking, it puts power to the red and blue wire. Red to the ICM/Resistance wire-coil. Blue wire to the 'S' terminal on the solenoid.
2. The red wire on the 'I' terminal of the solenoid goes directly to the coil. This wire bypasses the resistance wire to give the coil full voltage while starting. The picture is deceiving. There is full (12V) when cranking and approx 9V when running.
3. Yes, the pictures should be what you see at the base of the steering column.
4. Correct the Alt is not needed to start the jeep.
 
#12 ·
This diagram may help a little to understand those wires. A generalisation of wire colours in a CJ:

Red - permanently live. You will see these in the charging/battery circuit and going up to the ignition switch. After the ignition switch, they are coloured according to how they are switched and wher they are gping.
Black - Ground.
Red with tracer - usually ignition. Switched power, live in Run and Start.
Blue - usually starter. Switched power, live in Start only
Orange - interior lights. Switched power from light switch
Yellow - instruemnts. Switched power, live in Run and Accy

There are a lot of exceptions to this but the diagram may help you visualise what is happening in the main circuits.
 

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