1969 J-3600 232 coil voltage question

[J20Hunter1]

First question I have, should there be a ballast /resistor block inline with the12volt feed to +side of coil on a 1969 232 .Mine has one and I have 12volt on both terminals of coil.Key on and start voltage reads 12volt.Or is there something I am missing?
Thanks for the help

[Stuka]

The voltage works in two stages. On the starting solenoid, there is two outputs on the front. One is for starting, and one is for running. The starting post only gets voltage when the key is in 'start'.

When the key is in 'start', the ballast resistor is bypassed and a full 12V is sent to the coil.

When the key is in 'run' the ballast resistor should be dropping voltage to around 8V or so. If you run a full 12V to the points, you can burn them up. Its possible somebody in the past bypass the ballast resistor.

Do you know if maybe a later ignition was swapped in? As later electronic ignitions are typically ok with a full 12V.

[tgreese]

Mmm. The ballast resistor resistance and your coil primary resistance make a voltage divider only when the points are closed. When the points are open, the circuit is open and you have full voltage (12V) everywhere between the ignition switch and the points, ballast resistor or not.

The voltage divider is likely the most important circuit to understand.

VoltageDivider.png

https://en.wikipedia.org/wiki/Voltage_divider


Here Vin is 12V from the ignition switch, R1 is the ballast resistor and R2 is the ignition coil. The points are closed, so the coil (R2) is grounded. Stuka is suggesting you should measure 8V at Vout.

Typical ballast resistors have about one ohm of resistance, and typical coils may have two ohms or less. With these values, Vout = Vin * R2 / (R1 + R2) = 12V * 2 ohms / (1 + 2) ohms = 8 volts.

The ballast resistance and coil primary resistance can vary, and it's really hard to measure these low resistances accurately with the inexpensive equipment available to us. Thus I would say that Vout should be a very loose 8ish volts. No voltage drop or most/all voltage drop is a problem - but you should see some drop.

When the points are open, you will see 12V at the switch and 12V on both primary terminals of the coil - no voltage drop.

The starter switch will bypass the ballast resistor when starting, and Vout will be full voltage, 12V. Then you will have the full voltage drop across the coil when the points are closed.

[J20Hunter1]

Thanks guys .Lookks like PO wired in ballast .I removed ballast and and works great ,started right up.

[Stuka]

Thanks guys .Lookks like PO wired in ballast .I removed ballast and and works great ,started right up.

Are you still running points?

You don't want to leave the ballast resistor out of the circuit permanently as it will cause the points to fail.

Its possible your resistor is open and just needs to be replaced.

[J20Hunter1]

It had voltage going through it .I couldnt find anything in factory service manual where it showed a ballast on 232 .The ballast got really hot.Could it have been going bad? Crazy

[J20Hunter1]

I am running points .I am just trying to get running ,then decide plan for future mods

[Srdayflyer]

I ditched the factory ign. on my 232 in my cj5 with a g.m. style distributor and havent looked back, it was only 50.00 (new)and was the best money ever spent.

[tgreese]

The parts book says you should have a ballast resistor, Jeep PN 938987. All 232-258-304-350-360 in J-series vehicles through '73 use the same one.

https://www.rockauto.com/en/moreinfo.ph ... 52&jsn=276

Do you have a multimeter and know how to use it? The resistor should measure very low resistance, like an ohm or two. High resistance will still show voltage at the coil if the points are open, but limit current so much that the coil won't fire.

[J20Hunter1]

Thanks Tim I looked in service manual not parts .Thanks again for your help.

[tgreese]

NP Dennis. The resistor appears to be item #22 on the FSM wiring diagram.

[J20Hunter1]

In my factory Jeep service manual wiring diagram for 1969 truck with 232 engine does not show this.I will put one in .I will check wiring diagram off Toms site.
Thanks

[tgreese]

Huh. I don't have the book as a book, and was looking here. https://oljeep.com/gw/elec/69-71_350/69 ... _color.jpg

The diagram says '69 350 and the parts book includes the 232 in the listing for that part. Can't think of any reason why there would be a difference due to the 232.

Sorry for droning on here ... I would buy the part and put the resistor back. IMO its function is mostly to current-limit the coil primary, and keep as much of the electrical heating out of the coil as possible. Even with the resistor in there, with the points closed and key on, that's 8V-ish through a couple of ohms (typically - application dependent) giving 32 watts (P =V^2 / R). A 30 watt light bulb seems like a lot of heat inside the coil can. With the engine running, the duty cycle changes and the coil firing becomes an R-L-C circuit that's switched on and off at about 100 Hz. Hard to say what the heating will be like in operation.

There are coils with internal resistors added that don't need the ballast resistor. Possible you could look for a number on your coil and check that it's the right one for your application. If the resistor is not failing, it should not affect the engine running unless the coil is failing (maybe), even when used with the coil that has an added internal resistance. Easy to check the spark color and length as a quick test of the coil.

[J20Hunter1]

Yep factory manual shows a ballast on 350 .If you look 327 shows a fuse inline and 232 show nothing inline between ign switch .One of my old mechanic buddy that works on a lot of old jeeps and Int scout said 6 cylinder normally did not use a ballast.I didnt know why. Thanks for your help

[will e]

A side note. It is often written that the solenoid post provides '12 volts to the coil while cranking' or something similar. In reality it's lower because the voltage drops when the engine is being cranked. I often wonder if this was the point of this circuit. Does the voltage drop significantly enough that, along with the resistor wire, that the magnetic field isn't strong enough in the coil?

[tgreese]

Would also note - you can use the coil that does not need the internal resistor, but then you should not have the wire that bypasses the ballast resistor when starting. The parts book should show a different coil for the 232, if some were delivered that way.

[tgreese]

A side note. It is often written that the solenoid post provides '12 volts to the coil while cranking' or something similar. In reality it's lower because the voltage drops when the engine is being cranked. I often wonder if this was the point of this circuit. Does the voltage drop significantly enough that, along with the resistor wire, that the magnetic field isn't strong enough in the coil?

The bypass definitely juices the ignition when starting. The purpose could be either reason, or both - I have seen both arguments made.

[J20Hunter1]

Mine does not have the bypass wire.So I will make sure coil is the correct one for this set up.Its been a while since I have worked on one this old school My Prestolite original starter only has 2 contact points on it.I think PO changed coil and put ballast on it by the looks of new wiring on it.The rest of the wiring is all original,thank god .You guys are very helpful

[tgreese]

Looking at the parts book, a '65-67 232 uses a 3208860 ignition coil. The '68-on uses a 3208861.

Looking at the aftermarket listings, the 8860 crosses to a WVE 5C1019 which does not require an external resistor. The 8861 crosses to a 5C1026, which does require an aftermarket resistor.

Apparently, it depends on the year. A '69 should have a ballast resistor and the matching low-resistance coil.

Two points - first, such weirdness (not conforming to the books in odd cases) seems pretty common for Jeep. Also, these trucks were not assigned a model year at build time, and there is no model year in the VIN. I expect that was up to the dealership at sale time. Your truck might be older than you think.

If there were no numbers on the coil, I would replace it with the right one for your truck and keep what I had as a spare. If you have two wires going to the coil side of the ballast resistor, you definitely had/need a ballast resistor.

[tgreese]

... I think PO changed coil and put ballast on it by the looks of new wiring on it. ...

With no bypass wire, this seems likely. Maybe the external resistor coil is what was available.