CJ 5 Ballast Resistor

[CJ 74]

My 1974 CJ5 AMC 258 i6 / 4.2l AMC 258 i6 / 4.2l starts then shuts off immediately as soon as the key is released. Research suggests it's the ballast resistor. Looking at this part online I can't find anything that fits that description. The coil does say must be used with an external resistor. If this is the problem where is this part located? Hoping you guys can steer my in the right direction!

 

[Torxhead]

Does this post help:73/74 CJ5 Ignition Resistor Wire - JeepForum.com.

 

[Captainlance]

There is no resistor, per se. The resistance is developed by an inline piece of resistance wire between the coil and its power source. if it is open and no voltage is present at the coil, you may either buy a resistance wire and repair the harness, or eliminate it and buy a Mopar external resistor that was used from the 60's to 80's. Insert it where the original resistor wire was. It is a 1 ohm resistor and is available at any parts store.

However, I would first check the power source , which is switched by the ignition switch, to be sure you have any power at all.

My 1974 CJ5 AMC 258 i6 / 4.2l AMC 258 i6 / 4.2l starts then shuts off immediately as soon as the key is released. Research suggests it's the ballast resistor. Looking at this part online I can't find anything that fits that description. The coil does say must be used with an external resistor. If this is the problem where is this part located? Hoping you guys can steer my in the right direction!

 

[CJ 74]

Checked the positive coil terminal and wire with the key on using a 12 volt tester, no power. I traced the wires and didn't see anything that looked like a resistance wire. One wire went to the distributor and the other two follow the wiring harness. Is the resistance wire just a regular wire or does it plug in?

 

[Posi]

There should be a green wire that runs from the ignition switch to a pink wire (resistor wire). The pink resistor wire then runs to the + side of the coil.

There should also be a green wire that runs from the starter solenoid ignition side to the + side of coil. Those are the 2 wires that attach to the + side of coil.

 

[CJ 74]

I followed the pink wire off the + side off the coil, this went toward the front of engine along the wiring harness almost to the alternator then did a u turn and ran back to a male female connection at the firewall the wire was about 7 feet long. There wasn't any break in the wire indicating a bad connection. There was one wire where the harness connects that had a cut in the casing and looked corroded, may only be making a partial connection at best. The wire was blue with a yellow streak. How do I know if the resistor wire is any good and where would I cut it for replacement?

 

[Captainlance]

You will need either a volt meter ( VOM, multimeter) or a test light to check for voltage. A meter will give absolute readings of voltage, the test light is a go/no-go indicator. If you are going to work on cars, buy a multimeter, you will use it on a regular basis.
Lance

I followed the pink wire off the + side off the coil, this went toward the front of engine along the wiring harness almost to the alternator then did a u turn and ran back to a male female connection at the firewall the wire was about 7 feet long. There wasn't any break in the wire indicating a bad connection. There was one wire where the harness connects that had a cut in the casing and looked corroded, may only be making a partial connection at best. The wire was blue with a yellow streak. How do I know if the resistor wire is any good and where would I cut it for replacement?

 

[CJ 74]

Thanks. I will pick one up this afternoon.

 

[Posi]

Disconnect the 6 wire plug at the fire wall and check resistance from the plug pin C38 to the + side of coil. You should find resistance of 1.8

 

[CJ 74]

Separated the harness and tested the wire and had no reading at all. Tested the coil and had a primary reading of 1.4, tested the secondary on the coil again no reading. On the plus side I am the proud new owner of a multimeter. The corroded wire that looked like it was making a poor connection on the harness according to my Haynes manual is the temp gauge wire, i have been trying to get that working since I bought this jeep. The bad part of the wire is really hard to see since it's so close to the harness connector is it possible to run a jumper wire and bypass the harness connectors all together?

 

[Posi]

If you have no resistance on the pink wire its time to buy a new 1.8 resistor wire.

 

[CJ 74]

Bought a ballast resistor, I now have 1.8 on the pink wire. I also have the same problem jeep starts then shuts off immediately. I am confident it's getting gas I pulled a couple of plugs and they were wet. Going to buy a coil is there anything other than the coil or ignition switch that could be causing this? Both are inexpensive and I may just pick up both.

 

[Captainlance]

With the key in the "RUN" position, do you have +12 volts on the positive contact of the coil? If not, Your ignition switch could be either bad or miss-wired. If you do have 12+, then the coil may be defective.
Lance

 

[Posi]

Checked the positive coil terminal and wire with the key on using a 12 volt tester, no power.

By installing the BR you repaired the wire going to the coil.


Try this,
Start the engine
When it shuts down don't touch the key
Check for power at the + side of the coil
If no power wiggle the key and check for power again.

Could be a flaky ignition lock cylinder

 

[CJ 74]

Sorry Posi, just saw this post. Haven't been able to work on the jeep for a couple of weeks. This jeep came with a spare dash, I replaced the ignition switch with spare and had the same result. Never really starts and runs just starts to fire and dies out. I replaced the coil, wires and spark plugs. I pulled a plug and put it on the valve cover where I could see it and had good spark. When walked around the side of the jeep I could see gas seeping out of the throttle body. I let it sit for a couple of hours and tried again, gas is coming out at a steady rate. Not sure if this is a result of several attempts to start with no luck. But I now have a new issue to deal with. Appreciate all the responses. Getting quite an education working on this jeep. Really enjoy it.

 

[Posi]

Do you have the stock YF carb?
Is it leaking from the top or bottom of the TB, or both?
Could be loose TB to manifold bolts, or TB to carb bolts.
Float adjustment?
If it's leaking you don't have a good seal.
If the carb hasn't been rebuilt in awhile now would be a good time.
New gaskets on the TB as well.

 

[BusaDave9]

Checked the positive coil terminal and wire with the key on using a 12 volt tester, no power.

Here's your problem right here. When the ignition switch is in the ON position or the Start position you should have 12 volts on that positive wire on the coil.
It starts right up but dies when you release the key to the run position. That tells us that you do have 12 volts when the key is set to start. When you release it to the run position you should still have 12 volts but you don't and the engine dies. The same wires deliver the voltage when you turned to START and when you are set to run. The difference is the ignition switch itself. I say your ignition switch is bad.

Verify what I'm saying by checking the voltage on the positive terminal of the coil.
When the key is START you should have 12 volts.
When the key is ON you should have 12 volts. If you no longer have 12 volts it's the key ignition switch. All the same wires tested good when you were in the start position.

EDIT: Captainlance had it right. I didn't see his post or the 2nd page. But I don't think the coil is bad if the engine runs when in the start position.

 

[CJ 74]

VERIFIED.
Talked my wife into helping (took two beers but she helped) I had one lead on the negative terminal of the battery and the other on the positive terminal of the coil. while cranking I had a voltage reading as soon as it started to fire and she let off the key ( just to the run position) the reading died and so did the engine. No reading at all. Going to buy a new switch in the morning, hopefully that's that's the problem. I will follow up tomorrow. Thanks to all.

 

[CJ 74]

Installed the new switch and had the exact same result, fires and dies. Gas is leaking out of the carburetor pretty steady. Looking at my Haynes manual it appears to be leaking out of the throttle body where the spring and idle mixture screw attach. I have no experience with carbs so I will have to find someone to rebuild it. Hope to have it road and trail ready by this summer. Thanks for all the help.

 

[Posi]

There is no reason why anyone should waste time and money on electrical problems when the answer is there if you dig into it. You now have a good spare ignition switch.

There should be 4 positions on your ignition switch, batt, acc, start, and ignition.
We know the switch is grounded because the engine starts.
Check over the wiring to the switch to make sure it's correct.
Turn the key to the on position (not start)
Turn the wipers on, do they work?
If they don't you may have the switch wired wrong.
If they do I would inspect the ignition wire from the switch to the firewall plug.
Make sure voltage goes through the plug as well (could be gummed up inside the plug).
FYI, you will not have 12v at the coil with the key on with a BR wire, more like 5v-7v
The ignition switch wire runs from the switch to the firewall plug, to the coil.