1981 CJ7 ignition woes

[CT1944MB]

I have been following the troubleshooting guide on this forum for an engine that won't start: http://www.jeep-cj.com/forums/f99/engine-wont-start-troubleshooting-guide-19494/

I got to the point where the guide recommends checking the coil for 12 volts. The coil is getting about 6 volts. As far as I can tell, I do not have an aftermarket ignition module, so I should see 12 volts at the coil. When I looked for the ballast resistor, per the guide, I could not find it. So first question is, where is the ballast resistor located on a 1981 CJ7 ?

Second question is, is there anything else I should be looking for to figure out what is wrong?

Thanks.

 

[Lumpy Grits]

:ww:
You should read 6VDC with the switch in the 'run' position and 12VDC in the 'start' position.
Try run'n a 'jumper' wire from the POS(+)side of the battery to the POS(+)side of the coil. If it starts(don't run it for more than a couple of minutes)your issue may well be in the ign switch. Also-That horseshoe connector on the coil is a well know problem area for bad contacts.
You'll have to pull the jumper wire to shut down the engine.
The ballast-resistor is a wire in the loom going across the firewall.
LG

 

[Torxhead]

That ballast resistor wire is a non wear item that should not need replacing unless it breaks. You might want to pull a spark plug wire and check for spark to determine weather it is a fuel or an ignition issue and go from there. Did this no fire issue just happen all of a sudden?

 

[CT1944MB]

I have checked for spark by pulling one plug at a time using the old plugs. I also tried a spark tester light. I then tried a new plug. In all cases there is no spark.

The guide on this site I mentioned said to test the ballast resistor. The post shows a picture of a ballast resistor and that is what I have been trying to find.

Is there a way I can test the ignition switch?


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[Lumpy Grits]

The resistor in the late model CJ was a wire inside the loom that goes across the engine side of the fire wall.
Easy to find and the connectors are not the best used.
LG

 

[Peanut Butter]

It's always a good idea to have a good wiring diagram for any electrical troubleshooting. I personally like this one: Jeep | Prospero's Garage Below is a diagram that may help some. Look for posts from Team Rush. This guy really knows his electrical stuff.

 

[CT1944MB]

Thanks for the diagram. I had a chance to test voltages again. In the run position, the + terminal on the coil was getting 6 volts. When the ignition switch was turned to the start / cranking position, the coil + terminal was getting 9.6 volts. What would cause this? Shouldn't it be getting 12 volts? Would this indicate a bad ignition module or ignition switch?


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[Lumpy Grits]

The higher start voltage to the coil is normal, as the starter is suc'n all the 'juice' to turn the engine over.
I'm surprised the start voltage isn't closer to 12VDC.
I would have your starter test'd for AMP 'draw'.
LG