Question about electrical

[JimyB]

I am presently rewiring my 86CJ7 and have a question to ask anyone with the perverse and misunderstood ability to read wiring schematics. What the heck is the capacitor jumper for? I believe its that white thing attached to the firewall on the engine side. I have never seen it in any other vehicle and am wondering what it's purpose is.

 

[Torxhead]

Well, I have an '86 and would like to know also. Are you referring to the white wire with a eye terminal at the end of it?

 

[Darren9975]

Sounds like an old balist resistor?

 

[JR74CJ5]

Pictures pictures pictures...

The part, schematic in question (highlight part with microsoft paint first if poss...) or heck even of the jeep itself for that matter... Always like pics of jeeps...

All joking aside, (well, above) pics worth thousand words here...

 

[BusaDave9]

A capacitor (sometimes called a condenser) Will not let DC current pass through it but like to maintain a constant DC voltage across it. It is often used to prevent a spike in voltage. I am not sure about the capacitor you are talking about but they are used on point ignitions. The points open and close so fast that a spark may jump across the points. A condenser can be used to prevent the arch by giving the electronic charge a place to go when the points suddenly open.

A coil is the opposite of a capacitor. It easily lets DC current pass through it but likes to maintain a constant current through it. It is often used to prevent a spike in current.

BTW an ignition coil is a misnomer. It's actually a transformer and not a coil.

 

[JimyB]

A capacitor (sometimes called a condenser) Will not let DC current pass through it but like to maintain a constant DC voltage across it. It is often used to prevent a spike in voltage. I am not sure about the capacitor you are talking about but they are used on point ignitions. The points open and close so fast that a spark may jump across the points. A condenser can be used to prevent the arch by giving the electronic charge a place to go when the points suddenly open.

A coil is the opposite of a capacitor. It easily lets DC current pass through it but likes to maintain a constant current through it. It is often used to prevent a spike in current.

BTW an ignition coil is a misnomer. It's actually a transformer and not a coil.

K, this is like latin to me. I appreciate the input but I lack the basics for electrical and am just trying to learn my way thru it. I'm sure I will understand at some point but it will take me awhile. LOL.
K here's the pics, tell me what it is and what it does and why I have it in my jeep but have not seen it in any other vehicle of the same age and is it even the capiciator jumper.

 

[Torxhead]

You won't find that in the oem wiring schematic. it does look like a ballast resistor though. So what is it hooked up to ?

 

[JimyB]

One side goes to the voltage regulator and the other side....well that's a good question. I'm going to have to trace the other wire back thru the harness to figure that out. I'm wondering though if I can just completely bypass it though or does it have a purpose.

 

[Stodg73]

What you see my index finger pointing to is the capacitor jumper. I was told that it is used for reducing noise interference on the radio. It is attached to the coil by the red wire.

 

[JimyB]

What you see my index finger pointing to is the capacitor jumper. I was told that it is used for reducing noise interference on the radio. It is attached to the coil by the red wire.

Well that answers that then, but what the hell is that thing on my firewall then.....Frig

 

[Torxhead]

Voltage regulator? if so that would be another add on. I think those went out sometime in the mid '60s along with the generator. Unless you have a high output alternator with an external voltage regulator. Usually the regulator is inside the alternator, there is also a resistor wire that controls voltage.

 

[JimyB]

my bad, it's the starter solenoid, not a voltage regulator.

 

[Torxhead]

So, if one end is connected to the starter solenoid, which side is it connected to? There is the battery side, which has the battery cable going to it, or the starter side, that has the cable going to the starter. There is also a light blue wire which goes to the ignition switch and a red wire with a white tracer that goes to the coil. Could you also trace down the other end and see where it goes to?

 

[jeffgtoman]

It looks like a Chrysler resistor to me. If your distributor had points, this item would drop the RUN voltage to the coil from 12 volts to 6 volts. It made the points last longer. There would be another wire that sent 12 volts to the coil while you cranked the engine with the starter. Coils needed 12 volts to get the engine started. People used to use these on all makes of cars when they needed one. All of the other manufacturers used an inline resistor that was hard to find. This Chrysler style could be easily grabbed at a junkyard.

I don't know why you have it. Do you have points in your distributor?

 

[67Jeepster]

That white thing is called a ballast resistor. It is used to reduce the voltage to the ignition coil when the engine is running. It would only be hot when the ignition switch is in the on position. There should be two wires connected to the same terminal of the ignition coil. The second wire connects to the solenoid on the starter, this provides a full 12 volts to the coil for starting and the ballast resister provides about 6 volts when the engine is running.
The idea is to allow maximum spark while starting the engine and reduced stress on the coil under running conditions.

 

[BajaEdition]

If you bypass that resister completely you can expect to replace the coil every few weeks, they are not designed to work over 9 volts, that is the reason for the resister on the back wall. Now as far as a starting circuit bypassing it, I do not have that on either of my CJs. But I do not know if they put a bypass circuit on CJs past 1971.

 

[Torxhead]

BajaEdition, The op states that what appears to be a ballast resistor has one end connected to the starter relay, which seems to be odd. The later CJs do not have a ballast resistor but a resistor wire and do have a bypass jumper from the relay on the starter side to the coil. I'm sure you know that the newer e-type coils will accept 12 volts.

 

[BajaEdition]

BajaEdition, The op states that what appears to be a ballast resistor has one end connected to the starter relay, which seems to be odd. The later CJs do not have a ballast resistor but a resistor wire and do have a bypass jumper from the relay on the starter side to the coil. I'm sure you know that the newer e-type coils will accept 12 volts.

so I go read the first post and see I have egg on my face
I actually just looked at the pictures, and figured it was an earlier CJ
Yes why does he have a ballast resister on that jeep?
I seems that PO syndrome is at hand here.

 

[BusaDave9]

It may not even be used as a ballast resistor. It looks like a power resistor but I don't think it is connected to the ignition. One wire goes down to the starter solenoid on the fender. That end must always be getting 12 volts even when the engine is off. Where does the other end go? That's anyone's guess. You will have to trace the yellow wire.

 

[67Jeepster]

There should be three or four terminals on the starter solenoid, the only one to always be powered is the large one connected to the battery. The other large terminal goes to the starter. One small terminal is connected to the start switch to engage the solenoid.
A newer vehicle would not even have a ballast resistor as it has been replaced by a high resistance wire. These wires are of a specific length to provide the proper voltage. What ever the ballast resistor is hooked to will not be receiving 12 volts, depending on the difference between the resistance of the ballast resistor and whatever it is hooked to.