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Inline fuse continues to blow fuses

Challenger RTA

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#18(Alt.) were fried and drilled them out and ran wires straight trough.
We then discovered the 2 field wires coming out of the Alt. were fused together up aways, so I repaired those 2 wires.
I guess you can't unplug #18 alt wire. Unhook from alt stud remember still hooked to battery still hot.
 

Challenger RTA

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It seems to blow only while turning the motor over.
2 months ago, I made about 4 separate trips before it blew that fuse
I understand. Remove steering wheel and seat unless your 18. It will make it easier to get in there.I want to say it is the brown wire shorted out somewhere. It is for the start ign. Open the harness and find it. Fix it or replace it. There might be others.
By moving harness around while key in start position the fuse might blow.

When the alt shorts out or the battery wire on the alt is touched to ground, it more than likely destroys it and take a few other beside it.
 

magg383

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1 thing to do is unplug all the bulkhead connectors except the one from the battery the middle one and turn the sw on and to start see if it blows.
I know this is a shotgun approach but it will narrow it down inside or outside.

If it blows it is more than likely shorted somewhere in the dash harness. Like the pictures in post # 10

1 thing to do is unplug all the bulkhead connectors except the one from the battery the middle one and turn the sw on and to start see if it blows.
I know this is a shotgun approach but it will narrow it down inside or outside.

If it blows it is more than likely shorted somewhere in the dash harness. Like the pictures in post # 10
I have a home AC service man at my house now.

Like I said though, the fuse never blows from just turning ign. switch to the on position. Only blows while cranking the motor over.
So, I'm not for sure I understand what good it would do by unplugging the other 2 bulkhead connectors and just turning the ign. to the on position to see if it pops if that was not an issue before??
 

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To make sure there is nothing from beyond that point shorting it out. Process of elimination it's out of the problem. Like I said by moving the harness around it might short out while holding the key in the on in the start position.
 

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It might be an inrush current issue, since it works sometimes.
A short would blow all the time.
Try a slow blow fuse or up it to 40A and see what happens
 

magg383

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I understand. Remove steering wheel and seat unless your 18. It will make it easier to get in there.I want to say it is the brown wire shorted out somewhere. It is for the start ign. Open the harness and find it. Fix it or replace it. There might be others.
By moving harness around while key in start position the fuse might blow.

When the alt shorts out or the battery wire on the alt is touched to ground, it more than likely destroys it and take a few other beside it.
I see from my wiring diagram that the brown wire J3-14BN on engine side goes to ign. ballast, then goes to the + side of ign. coil
On dash side it goes to large 8way clear plug under column to ign. #2 (the plug looks healthy, no burn marks)

I'm guessing I will have to unwrap about 12" to expose and see all of that brown wire since its just from bulkhead to column??
I'm going to wait a day or 2 to start that though, Its 110 degrees w/ heat index here today!
 
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magg383

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1 thing to do is unplug all the bulkhead connectors except the one from the battery the middle one and turn the sw on and to start see if it blows.
I know this is a shotgun approach but it will narrow it down inside or outside.

If it blows it is more than likely shorted somewhere in the dash harness. Like the pictures in post # 10
I have not had a chance to start unwrapping tape under the dash yet.
In my service manual, I see that bulkhead #9 is classified as START "S2-18YL" at ign. switch on dash wiring side. (Maybe that wire could be fused together under electrical tape?)
On engine side it goes to the starter relay.
Is it possible that the starter relay has some type of short?

Also, what do you think what Katfish suggested?
 

Challenger RTA

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I have not had a chance to start unwrapping tape under the dash yet.
In my service manual, I see that bulkhead #9 is classified as START "S2-18YL" at ign. switch on dash wiring side. (Maybe that wire could be fused together under electrical tape?)
On engine side it goes to the starter relay.
Is it possible that the starter relay has some type of short?

Also, what do you think what Katfish suggested?
Everyone's guess is as good as the other. You don't know until you open it up.
 

Challenger RTA

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Is it possible that the starter relay has some type of short?
Yes the starter relay could short out inside. Change it if you have any starter relay.Any starter relay will work for testing purposes.
It could also be the ing sw shorting out in the start position. That's what I was suggesting in post #11 to test.

I'm more inclined to look at the wiring harness. but if there is something easier to check do it.
 
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magg383

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Unplug the the ign sw plug under the column and hot wire it to see what happens. Might be an ing sw, at least it will narrow it down.
Thought I would eliminate the ign. sw. like you mentioned. Could you tell me the step-by-step hotwiring process of checking it after unplugging the plug. Thanks!
 

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The red wire 12R is hot all the time. Jump from red wire to the following wires. DBL 12 that is the ignition 1 run. The 12 BR is ignition 2 for starting. Understand the Brown wire is for full voltage to coil for starting only. ( the brown wire is the one I suspect to be the problem. ) You can try just using the Dark Blue ignition 1 it might give enough power to the coil to start. Also apply power to yellow 12Y that is for the starter relay for starter to turn over and start. You could put the yellow and brown wire on the same switch because they both do function at the same time. It's a momentary operation.
You can use any switches you have there is no real high current for thesis circuits. If you have a house hold light switch and wire nuts can be used. Understand ( you probably do ) the starter switch yellow and the brown wire switch need to be turned off once it fires up

You can also touch the wire together if you can manipulate every thing.
1725669748278.jpeg
 
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Challenger RTA

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The same thing can be done under the hood. Unplug the engine wiring harness from the bulkhead connector. That will isolate the harnesses. From battery a connect to the DBL wire on the resistor also jump from the DBL wire to the Brown wire when starting. Then from battery touch the yellow wire on the starter relay. Remove jumper from brown wire once it starts. No big hurry just remove.
The motor will run until you disconnect power.
 

magg383

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The red wire 12R is hot all the time. Jump from red wire to the following wires. DBL 12 that is the ignition 1 run. The 12 BR is ignition 2 for starting. Understand the Brown wire is for full voltage to coil for starting only. ( the brown wire is the one I suspect to be the problem. ) You can try just using the Dark Blue ignition 1 it might give enough power to the coil to start. Also apply power to yellow 12Y that is for the starter relay for starter to turn over and start. You could put the yellow and brown wire on the same switch because they both do function at the same time. It's a momentary operation.
You can use any switches you have there is no real high current for thesis circuits. If you have a house hold light switch and wire nuts can be used. Understand ( you probably do ) the starter switch yellow and the brown wire switch need to be turned off once it fires up

You can also touch the wire together if you can manipulate every thing.
View attachment 128744
Please bear with me, I'm kinda a novice w/ this stuff. Questions:
1) Ign. in the on position during testing I'm guessing? 2)with plug disconnected? 3) testing wire section that comes from ign. sw.?
4) While jumping, is it OK to put a jumper wire (clip on) between 2 smaller Phillips screwdrivers to use as a jumper?
5) While going from red to other colors, what should I be looking for?
Thanks!
 

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With the plug unplugged the ign swith is out of the circuit. / You would be jumping the wires that come up the column. / As far as putting a small object into the plug any thing will work. Bare end of wire, paper clip alligator clip. Remember the red wire has the power. If it touches any thing it will energize the starter ,coil or what ever it touches. Ground!
What happens is when you connect to DBL wire there will be a small arc that will energize the coil same also for the brown wire. The yellow wire when energized will turn the starter over.There again there will be an arc. You only have that one to start the motor same as the brown wire is just for starting. The brown wire is what I'm suspecting to be the problem. It might smoke an get hot. That's why I say try it with out the brown wire. The dark blue wire might give it enough power to start. If not it only has to be connected when the starter is cranking.
As far as a novice we all been there at one time.
 

magg383

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I performed a continuity check on my ignition sw. from the red (batt) to the other 4 wire pins, yellow (start), blk (acc.), dk blu (ign. 1), and brn (ign. 2)

Ign. 1= No continuity w/ any other colors
Ign. 2= Continuity with blk and dk. blue only
Start, while in crank position= Continuity with yellow and brown only

Do these continuity test results represent a good ign. switch?
 

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On the ing switch side connector. Connect one lead to the red wire and leave it there. With the ign sw in the on position you should have continuity to the ign 1 blue wire as in the diagram. When turning the key to the start position you should have power to ing 2 brown wire and to the yellow wire. Let off the start position it should go off. Acc black wire will be hot when key is on.

Ign 1 feeds the ballast resistor to reduce voltage to the coil when running.
Ign 2 feeds the coil 12v power when starting only.
Yellow wire feeds starter relay when in the start postilion.
1726247388246.jpeg
 
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magg383

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On the ing switch side connector. Connect one lead to the red wire and leave it there. With the ign sw in the on position you should have continuity to the ign 1 blue wire as in the diagram. When turning the key to the start position you should have power to ing 2 brown wire and to the yellow wire. Let off the start position it should go off. Acc black wire will be hot when key is on.

Ign 1 feeds the ballast resistor to reduce voltage to the coil when running.
Ign 2 feeds the coil 12v power when starting only.
Yellow wire feeds starter relay when in the start postilion.
View attachment 128998
So, from what you're saying:
My continuity test: Start while in the crank position is OK

What about my continuity check on:
Ign 1 ?
Ign 2 ?
 

Challenger RTA

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I performed a continuity check on my ignition sw. from the red (batt) to the other 4 wire pins, yellow (start), blk (acc.), dk blu (ign. 1), and brn (ign. 2)

Ign. 1= No continuity w/ any other colors
Ign. 2= Continuity with blk and dk. blue only
Start, while in crank position= Continuity with yellow and brown only

Do these continuity test results represent a good ign. switch?
It seems as if you have ing 1 and 2 backwards in you understanding of testing. How ever you look at it, Keeping one test lead on the red wire. The brown wire and the yellow wire should have continuity in the ing start position only. The dark blue and the black in the ing sw on postilion. that the only thing you check. If it doesn't work that way it's bad.

As in Katfish's diagram,you will be testing the bottom 5 wires. Battery 1 , ign 1, ign 2, acc and start wires.
 
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