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Discussion Starter · #1 ·
In the wiring diagram of my 79 CJ7 there is a brown wire that is labeled "resistance 15.0". It is a different style wire than the others also. Is this a speical type of wire, or can I just replace it with some stranded brown wire. There is also a red wire leading to the coil that says "resistance 1.35". Saem question on this wire. I am not really sure what the resistance is for. If anyone can help me here, it would be appreciated. I am trying to avoid the $400 for a painless harness,

Jesse

 

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/wwwthreads_images/icons/tongue.gif Those wires are like a "choke" they reduce the voltage by having such a small wire for such a long distance. You should either salvage them, or you can buy a wire size which is exactly the same so that the resistance will be the same as well. That red wire reduces the voltage to the coil down to about 9 volts, but while the Jeep is cranking the OTHER red wire that goes over to that pole on the start solenoid gives the coil a momentary squirt of full 12V for better starting./wwwthreads_images/icons/crazy.gif

CJDave
Quadra-Trac modified by the crack moonguy/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/smile.gif/wwwthreads_images/icons/tongue.gif transfer case team.
 

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I concur with CJDave, however, speaking for the red wire to the coil...the resistance takes place somewhere before the firewall. Just this week I was trying to figure out why I had zero volts at the coil after the start sequence, as part of my testing I check continuity and also ran 12 volts to the start of the wire at the firewall plug...and got 12v out the other end near the coil...so I would say that at least between the firewall and the coil there is nothing special about the red wire...just a red wire w/white stripe. Cant speak for the brown wire.

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JK
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78CJ5 360
 

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/wwwthreads_images/icons/tongue.gif Don't forget/wwwthreads_images/icons/tongue.gif...if there's no flow....there's no voltage drop/wwwthreads_images/icons/smile.gif The red wire from the firewall to the coil is marked as "resistance 1.35 Ohms" in the Haynes(that's what I based my answer on). I know that the module has full volts, so it made sense to me that the Haynes was correct. Maybe when you checked it the coil was unhooked?/wwwthreads_images/icons/crazy.gif/wwwthreads_images/icons/tongue.gif

CJDave
Quadra-Trac modified by the crack moonguy/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/smile.gif/wwwthreads_images/icons/tongue.gif transfer case team.
 

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Maybe the voltage is reduced at the module?? I read the same thing in the Haynes manual, but I am here to tell ya that if you unplug that wire from the firewall and jump 12v to it, you will get 12v at the coil, even when hooked up to the coil. Therefore, my conclusion that there is nothing special about the wire...at least between the firewall and coil...it must be reduced elsewhere, and that may very well be the module.

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JK
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78CJ5 360
 
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Discussion Starter · #6 ·
The browm resistor wire is for the Delco alternator IGN on wire, It prevents voltage feedback into the ignition system preventing run-on. You can subtitute a 15 ohm power resister or simply add a diode to the wire to prevent feedback to the ignition system. The red 1.35 ohm resistor wire is used to drop voltage to the coil to around 9V so as not to burn it out. Here again you can buy a ballast resistor and accomplish the same thing. The original type of resistance wire is sometimes available at a good parts store or wiring supply specialist, but the balast resistor and diode will only cost a few dollars and will work just as well. Hope this helps, good luck!

 
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Discussion Starter · #7 ·
I was wondering what type of diode I need to get to replace the brown wire. What power rating will I need. Maybe someone has done this from experience. I remember doing diode problems in an electrical engineering class, but i never could get those problems right ;-) (I am a mechanical, not electical engineer) Also, is there a specific type of balast resistor I need.

I am also wondering why I would want only 9 V to the coil. I hear that with old points systems this was used to keep the points from burning up, but with a non-points ignition, why do I want only 9V to the coil. Wouldn't 12 V to the coil be a good thing?

Jesse

 

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*CJ-8/5.2Mag* stated,
*The browm resistor wire is for the Delco alternator IGN on wire, It prevents voltage feedback into the ignition system preventing run-on. You can subtitute a 15 ohm power resister or simply add a diode to the wire to prevent feedback to the ignition system.*

Incorrect.
The resistor wire in the charging circuit is to excite the voltage regulator even when the manufacturer uses too small of a bulb in the 'idiot' light.
The amount of
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*The red 1.35 ohm resistor wire is used to drop voltage to the coil to around 9V so as not to burn it out.*

Incorrect.
The resistor wire is not a 'voltage drop' device. It is a Choke. It simply impedes the CURRENT... (not voltage)

If you only have 9 volts at your positive coil terminal, you have a LARGE problem...

The Automotive ignition coil is just a simple transformer type winding set..
The ignition coil is capable of taking several hundred volts with no damage.

The resistor wire is there to add a little resistance to the system to keep from over taxing the MODULE... It has nothing to do with the coil.
The coil gets it's ground through the module, and the coil can draw as much as 50 amps in high load situations. The resistor wire simply keeps the coil from killing the module.
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*Here again you can buy a ballast resistor and accomplish the same thing.*

This part is true.
You need somewhere between 0.75 to 3.0 Ohms for the DuraSpark module and TFI coil.
The factory resistor wire is 1.35 Ohms, and the TFI coil is around 0.45 Ohms.
The two together are more than enough to keep from frying the module.
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*The original type of resistance wire is sometimes available at a good parts store or wiring
supply specialist, but the balast resistor and diode will only cost a few dollars and will work just as well.*

The factory type resistor wire is available at most parts stores.
The Wells (Auto Zone) P/N F799, and is $9.00.
Order for a 84 Ford 1/2 ton pickup with V-8.
It is 49" long, and can be cut to length to get your required resistance.
Resistance wires are the most dependable.

If you are building from scratch, you can also use a Porcelain 'Pot' type resistor.
I prefer the resistor from a 76 Chrysler New Yorker. It has two resistors built into it, and if one fails, the other will get you home.
I usually use the side that has about 1.30 Ohms resistance. The 5.0 Ohm side will work also.
Wells (Auto Zone) P/N CR105, and is $1.90.
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NO IGNITION RESISTOR IS REQUIRED WITH AN MSD MODULE.
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NO IGNITION RESISTOR IS REQUIRED WITH AN INTERNALLY RESISTED COIL. Resistance is built into the coil.
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The Resistor ALWAYS goes in the positive feed wire to the coil.
Never add the resistor to the ground side of the coil.
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NO MATTER WHAT ANYONE ELSE TELLS YOU...
The Dura Spark Module ALWAYS gets a full 12 Volts, with NO RESISTOR!
That is to both sides of the power connector, Both Red (cranking power) and White (run power).
The module is an electrical device, and it operates on 12 volts.
If you lower the voltage to the module with a resistor, like some have suggested, you will spend a lot of time changing modules.

So Many Cats, So Few Recipes...
 
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Discussion Starter · #9 ·
Teamrush:
In summary... I can get the resistance wire from an 84 1/2 ton ford w/V8 (autozone part number F799) to replace the RED resistance wire in my CJ 7 harness. This will help prevent the frying of the ifgnitoion module, which has been an issue in the past (I believe this wire was replaced with a normal wire in my current harness).

What do I do about the brown resistance wire? I do not think I even have an "idot light" anymore. Can I find a replacement for this, similarly to the red one.

I am just trying to "re-do" my wiring harness. The previous owner was liberal with the snips and electrical tape. I am also going to mount the ignition module in the tub, on the firewall, to help keep it dry, and free from mud. I have created a schematic, from the haynes manual diagram, routing the wires in the engine bay for a "clean" look. I have all the other wires, I just need a way to replace these two unique wires. I know there is a brown resistive wire on there presently, but I am not sure how good of shape it is in, or if it is long enough.

I have also ran into another problem....

The alternator is the Delco type. I have a new pigtail, with one red, and one white wire coming from the alternator. The diagram show a red wire from alternator to solenoid, and the brown resistive wire. Do I connect the red wire to the red, and then the white pigtail wire to the brown resistive wire? I think this is the only logical way.

Thanks for all the help.
Now I know why Painless chose the name "Painless" I will call mine the cheap, but painful harness.

Jesse

Ignorance is the first step to knowledge.
 

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See if the attached document helps...

You can get a 1 watt, 150 ohm resistor at radio shack to replace the idiot light for exciting the alternator.

The one wire alternators just don't live that long (defect in the regulator design).
Small case alts. won't live if you throw big loads at them, and so called 'High Output Upgrades' always cause problems.

If you want to convert the GM 10-SI, 12-SI, 15-SI and 116 Type and the like, internally regulated, alternating generators to use on your vehicles, you will need a few things.

1, You will need a 12ga. or 14ga. fusible link or fuse wire.
2, You will need a 12 volt light fixture that has a controlled ground.
(Has two wires, and doesn't ground through the housing or bracket)
3, A GM Style, two wire alternator plug that connects to the side of the alternator.
4, A length of at least 10 Ga. wire (I prefer 8 Ga.) in red insulation.
5, A length of at least 8 Ga. wire (I prefer 6 Ga.) in black insulation.

Connect red wire to the large insulated terminal on the back of the alternator case marked 'BATT'. (8 Ga. recommended)
Connect that wire to the fusible link.
Connect the fusible link to the battery cable side of the starter solenoid.
Your positive battery side hook up is complete.

Run a ground wire (At least one size larger than the charge wire, 6 Ga. recommended) from the ground wire boss on the back of the alternator to battery.
Engine ground, alternator bracket, ect. are unacceptable as substitutes.
Your negative battery side hook up is complete.

Find a wire that is only hot while the Ignition switch is in the 'RUN' position.
(This circuit must be 'off' when the key is turned off.)
Connect to that wire with two leads...
The first, about 16 to 18 Ga. wire, travels through the 'Idiot' light, and then to #'1' terminal on the alternator plug. (Usually a white wire, and smaller than the #2 wire)
The second, about a 14 Ga. wire, travels straight from the switched source to the #'2' terminal on the alternator plug. (Usually a red wire)
Plug in the Alternator, and see if it charges.

Notes:
If you find an alternator that came out on a vehicle that had air conditioning, and a rear window defrost, you probably have a factory high output unit. Look for the standard size cases though, as there were some odd-balls put out on luxury cars.
If you are going to do deep water fording, or in excessively dusty conditions there are totally sealed units out there. I found about a dozen the other day at the army surplus store for $10 each!

Contrary to what urban myth has to say, an alternator does NOT care which way it turns.

LED style lights will NOT work. It needs to be a regular automotive style bulb. Small dash style bulbs are perfect.
You must have a light socket that controls the ground, as when the alternator is charging, there is 12 volts positive to BOTH sides of the light.
In cases where a light is not wanted, a 100 to 150 Ohm, 1 Watt resistor can be used instead of the light. I like the light idea better...
Almost any automotive parts store will have the parts described above.
Some people substitute a toggle switch for the ignition switch feed, but if you forget to turn off the switch, it will run the battery down, and possibly damage the alternator.

Don't forget to use star washers on all electrical connection, and use a good quality lead plated copper wiring ends. If you are going to be in wet climates, or salted roads, don't forget to solder the ends on, and use heat shrink tubing to make the connections bulletproof. Never trust store bought cables!

If you connect the #1 and/or #2 terminals to the BATT terminal or the battery, like some have suggested, you will have problems. Take your regulator control source (#1 & #2) from inside the vehicle. Your alternator will then compensate for any accessory and parasitic loads that way.

WARNINGS!!!
DO NOT EXCLUDE THE FUSIBLE LINK!
If you don't fuse the system, you stand a very good chance of a fire!
ALWAYS use a fusible link smaller than the charge wire. (Example: If you use a 10 Ga. charge wire, use a 12 or 14 Ga. fuse link. Larger the number, the smaller the wire)
DO NOT attach the fusible link to the battery! If the system grounds and the fusible link burns violently, it can be an ignition source for the battery gasses. Your best bet is the battery cable side of the starter solenoid. This arrangement works on Ford & Mopar engines also.

TROUBLE SHOOTING:
If you have a GM vehicle, (or a GM conversion) and the battery and alternator both test good, but it still will not charge, Check these three things...
1. Check the idiot light. The system won't charge reliably if the bulb is burned out or missing.
2. Check the fusible link. The fusible link is a soft wire with tape or a plastic collar about 4 or 5 inches from the end.
(Plastic collar is about 1 inch long X 1/2 inch dia.) The fusible link is usually found connected to the battery cable side of the starter solenoid.
3. Check to make sure the alternator is grounded. A good 85% of alternator problems are ground related.

Most factory installed alternators rely on engine ground or alternator bracket ground to service the alternator. BAD IDEA!! Outside of the starter, the alternator will require the largest capacity ground!
Rust on brackets, blocks or in bolt holes, painted surfaces, and loose fasteners all contribute to loosing ground capacity. It doesn't have to be a total break in connection to cause problems or kill the voltage regulator.
The reason the factory didn't dedicate a ground wire to the alternator is $$$. By doing a 'Close Enough' ground, they save the cost of the wire, connection ends, and labor to install it.

"I Have The Body Of A God... Buddha"
 

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Discussion Starter · #11 ·
Jesus, its a wonder my alternator ever sharged at all. It had to be some kind of osmosis thing, because my alternator was not hooled up like that! It is the same style, just it was hooked up a little differently... ha. The previous owner must have been trying to save money by not installing a couple wires on each device .....

Jesse

Ignorance is the first step to knowledge.
 

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Just trying to help...
If you have any other questions, just ask...

"I Have The Body Of A God... Buddha"
 
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