Ignition issues.

[Sc37206]

1975 CJ5 AMC 304
Engine fires when cranking the starter, then when I let go of the key, it immediately dies. Can't push more gas, just no ignition. I have replaced the starter, cylinoid and tried to hot wire it. All to no avail, please help. When I hot wired it i took the three wires off the ignition switch and touched them together, when it fired I removed the starter wire and it died, did I do that wrong? Could it still be the starter switch?

 

[Torxhead]

Check the wiring to the starter relay. The light blue wire goes to the "S" terminal and the red with a white tracer goes to the "I" terminal. At least that is the way it is on the newer CJs.

 

[Sc37206]

Thing is, it ran great until two days ago. I started it, was letting it warm up, hopped in, put it in reverse, then, nothing. Dead.

 

[Saddle Tramp]

1975 CJs came with a Prestolite ignition system which is junk. My bet is that the module is toast if not the whole system. Per Junk Yard Genius the best swap is to upgrade to a 1978-1979 Motorcraft/Dura-Spark ignition. Check This:

http://www.junkyardgenius.com/ignition/jeep/jeep04.html

 

[BusaDave9]

Could it still be the starter switch?

Could be but don't replace it yet. We get too many people shotgunning problems here on this site because of people guessing what's wrong.
We need to test a voltage. If you don't have a volt meter a test light will work.

If the starter will crank all you want then we know the starting system is good.
So it seems to start but when you release the key it dies? Correct?

Check the small positive wire to the coil for voltage. This should be red and white but might be only red. This should have 12 volts when the key is turned to start AND when the key is in the run position. If it has 12 volts when the key is turned to start but drops to zero when the key is set to run then you are right and you need a new ignition switch.

Another test to make sure we are on the right track is to wire up 12 volts from the battery to the positive side of the coil. This will bypass the ignition switch. If the ignition switch is bad the jeep will start up and keep running. Actually it will keep running even after you turn off the key but this will verify that you need to replace the switch. The electrical portion of this switch not the keyed part is what needs to be replaced.

EDIT: I had to edit what I said. Jumper from the battery to the + of the coil.

 

[Old Dog]

1975 CJ5 AMC 304
Engine fires when cranking the starter, then when I let go of the key, it immediately dies.

Sounds like you ballist resister wire went out on you.

 

[BC CJ]

When my ignition module crapped out starting sounds normal but it just wouldn't fire (no spark being generated). If yours is firing then it's probably something else but it's pretty easy to plug in and ground a new module to test it - you should carry a spare anyhow

 

[mtnwhlr]

Could be but don't replace it yet. We get too many people shotgunning problems here on this site because of people guessing what's wrong.
We need to test a voltage. If you don't have a volt meter a test light will work.

If the starter will crank all you want then we know the starting system is good.
So it seems to start but when you release the key it dies? Correct?

Check the small positive wire to the coil for voltage. This should be red and white but might be only red. This should have 12 volts when the key is turned to start AND when the key is in the run position. If it has 12 volts when the key is turned to start but drops to zero when the key is set to run then you are right and you need a new ignition switch.

Another test to make sure we are on the right track is to wire up 12 volts from the battery to the positive end of the battery. This will bypass the ignition switch. If the ignition switch is bad the jeep will start up and keep running. Actually it will keep running even after you turn off the key but this will verify that you need to replace the switch. The electrical portion of this switch not the keyed part is what needs to be replaced.

This is good advice but I think what Dave ment to say is run a wire from the + on the batt to the + on the coil and try starting it.

 

[Sc37206]

Busadave9, thanks so much for the info! I have one question, about wiring the volt to the battery? Do you mean to the coil? Can you try and tell me again? I may be asking a stupid question but I don't understand what you mean yet.

Another test to make sure we are on the right track is to wire up 12 volts from the battery to the positive end of the battery. This will bypass the ignition switch. If the ignition switch is bad the jeep will start up and keep running. Actually it will keep running even after you turn off the key but this will verify that you need to replace the switch. The electrical portion of this switch not the keyed part is what needs to be replaced.[/QUOTE]

 

[BusaDave9]

yes, I meant to say take a wire from the positive end of the battery and route it to the positive end of the coil. It should be a red and white wire and the coil should have a + marking.

 

[Sc37206]

yes, I meant to say take a wire from the positive end of the battery and route it to the positive end of the coil. It should be a red and white wire and the coil should have a + marking.

So, I tried to direct line the coil. Turned over and then stopped. No start. Now I can touch the cool to the battery, sparks but won't turn over the engine. Bad coil?

 

[BusaDave9]

Check to make sure you have a spark when you are cranking. Use a spark tester like this:

Sounds like you ballist resister wire went out on you.

Old Dog may be right. Do you have a ballast resistor? If so how many wires are on it? 2 at each end or one?

 

[Sc37206]

Check to make sure you have a spark when you are cranking. Use a spark tester like this:



Old Dog may be right. Do you have a ballast resistor? If so how many wires are on it? 2 at each end or one?

Ok, what's a ballast resister?

 

[Sc37206]

Sounds like you ballist resister wire went out on you.

I have one but no wires have ever been connected to it.

 

[Sc37206]

Anyplace I can buy a prestolite ignition module for a 75 CJ5 ? It's not the one on eBay, I need the one that fits the 74-75.

 

[BC CJ]

I sourced one through the local parts store... Morris 4x4 has them also.

OK, I just looked at the pic. That looks like the newer style duraspark module. Must have been swapped in by a PO.

 

[Sc37206]

I sourced one through the local parts store... Morris 4x4 has them also.

OK, I just looked at the pic. That looks like the newer style duraspark module. Must have been swapped in by a po

I ended up finding out it was the ignition switch, replaced it and was off and running!

Now, I have a new ignition problem. No spark from the coil. I think this time it is the ignition module, I've opted a closer look at it. Can you tell what year it's from or what to replace it with?

 

[hdgapeach]

Most electric control modules cover a span of years. Grommet color where the wires enter the box generally determines the module you'll need to replace the one you have. Some are blue. Some are brown and I wouldn't doubt that there's a few other colors that I haven't seen.

If you replace the module and it solves your problem, shim your new module so it has space between the surface you mount it to. That'll aid in cooling the box which will possibly extend the useful life of the unit. Heat helps kill the modules.

If it fixes the problem, go back to the store and buy a second module to use as a spare. A module going out when you're a long way from your destination can turn into a minor nuisance if you can reach in the console and plug in a replacement in about five minutes. They aren't expensive and they are like a light bulb; work forever or fry the first time you start the vehicle. You can't ever tell. Worth it to have a back up.

 

[Sc37206]

Most electric control modules cover a span of years. Grommet color where the wires enter the box generally determines the module you'll need to replace the one you have. Some are blue. Some are brown and I wouldn't doubt that there's a few other colors that I haven't seen.

If you replace the module and it solves your problem, shim your new module so it has space between the surface you mount it to. That'll aid in cooling the box which will possibly extend the useful life of the unit. Heat helps kill the modules.

If it fixes the problem, go back to the store and buy a second module to use as a spare. A module going out when you're a long way from your destination can turn into a minor nuisance if you can reach in the console and plug in a replacement in about five minutes. They aren't expensive and they are like a light bulb; work forever or fry the first time you start the vehicle. You can't ever tell. Worth it to have a back up.

Mine is blue and says standard on the front.

 

[hdgapeach]

Same as what I have on all my Fords and CJ5 . Take it with you to the store and tell the guy you "need one of these". They'll want a year make and model. I think you'll be good to go if you tell them a '77 Ford F150 with a V8. You can take the new one out of the box and compare it to the plugs and grommet color you have on your old one to verify.