fried harness again. Walk me through this.
#2639800
04/01/19 06:47 PM
04/01/19 06:47 PM
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Joined: Mar 2005
Posts: 1,630 North Central Florida
eightlitermopar
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1971 Plymouth Roadrunner, 383 with auto. Electronic ignition. The fried wire harness continues. For my original story, the original post is here. https://board.moparts.org/ubbthreads/ubbthreads.php/topics/2373445/1.htmlThe car was running great, parked it with the battery disconnected for 3 weeks. Went to move it and go for an afternoon drive. Hooked up the battery and it starts crackling and smoke from under the hood. Wires cooked but not as bad as before. I will probably need to remove the instrument cluster again which I am not looking forward to. Anyway, today I was poking around with my 12 volt test light just to see if anything looked weird. Here is my question. I need someone to walk me through this. I am hooking up the battery NEGATIVE like normal, but I am leaving the positive cable unhooked to avoid any fireworks. My 12 volt test light is hooked to the positive battery side, so I am testing to see where my continuity or short may be. When I ground it, the light comes on. My ignition key is OFF. What circuits should I expect to be “HOT” all the time? Or, when my test light lights up, what is ok and what is suspicious? I know any ground or ground wire will light up. The starter relay wire and terminal on the starter? The Ammeter? What else? Thanks in advance for any input. Eightlitermopar
Mopar or no car
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Re: fried harness again. Walk me through this.
[Re: eightlitermopar]
#2639923
04/01/19 10:03 PM
04/01/19 10:03 PM
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Joined: Feb 2010
Posts: 1,645 Phila. Pa.
Mattax
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Sorry this recurred. I still think it will really help tracking this down by noting every wire and connection showing damage. Two examples here http://www.heritech.org/cuda/Charge2.html#Fusible_Link_In_ActionModify the diagram to match your '71. If you want help, let me know. I think I downloaded '71 FSM since last year. We can make it a little more like tha factory like I did here. http://www.heritech.org/cuda/Charge.html#Charging_Wiring_DiagramI assume someone added the electronic ignition. So you'll have to help on how its been wired in. Hooked up the battery and it starts crackling and smoke from under the hood. Correct me if I'm wrong. It did not start to smoke until after you closed the hood. It started to smoke when you turned the key to run or start. If so which one? Anyway, today I was poking around with my 12 volt test light just to see if anything looked weird.
Here is my question. I need someone to walk me through this. I am hooking up the battery NEGATIVE like normal, but I am leaving the positive cable unhooked to avoid any fireworks. My 12 volt test light is hooked to the positive battery side, so I am testing to see where my continuity or short may be. When I ground it, the light comes on. Not sure what you are trying to do with the test light here. My ignition key is OFF.
What circuits should I expect to be “HOT” all the time? When the battery positive is connected to the stud on the starter relay, every wire downstream is hot until up until it is interupted by a switch, or at the alternator, the internal diodes. So the alternator feed is hot, the ignition switch feed is hot, the fuse box lead is hot, the headlight switch lead is hot.
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Re: fried harness again. Walk me through this.
[Re: 71birdJ68]
#2639924
04/01/19 10:03 PM
04/01/19 10:03 PM
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Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
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that would be mechanical, the pushbuttons, lol.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
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Re: fried harness again. Walk me through this.
[Re: eightlitermopar]
#2639927
04/01/19 10:08 PM
04/01/19 10:08 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
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Hot all the time: large cable to starter. brake lights/headlights/horn/dome light (you jump in the car & these will operate WO the key). I didn't read the prior thread but I will. power flows in past the bulkhead fusible link then on to/thru the ammeter then to the "welded splice" where it T's & goes to headlight switch/ign switch/horn relay then on back out past the bulkhead out to the alt. Any idea what part/area/system is dead shorting?
live every 24 hour block of time like it's your last day on earth
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Re: fried harness again. Walk me through this.
[Re: Mattax]
#2639984
04/01/19 11:32 PM
04/01/19 11:32 PM
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Joined: Feb 2010
Posts: 1,645 Phila. Pa.
Mattax
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In the previous thread I think you mentioned the alternator feed connection was damaged. I'd look there again. if its damaged then you know its down that line. Is something is spliced into that line? or is insulation damaged? If not, then it could be the output stud or rectifier inside the alternator is grounding.
Might do just as well with a cheap analog ohm meter rather than the test light and breaker. Disconnect the battery, then start checking for continuity to ground. Disconnect the alt, and then continue diconnecting and checking until you narrow the location, Thats how I'd do it.
Last edited by Mattax; 04/01/19 11:39 PM.
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Re: fried harness again. Walk me through this.
[Re: Mattax]
#2640006
04/02/19 12:29 AM
04/02/19 12:29 AM
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Joined: Mar 2005
Posts: 1,630 North Central Florida
eightlitermopar
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Hooked up the battery and it starts crackling and smoke from under the hood. Correct me if I'm wrong. It did not start to smoke until after you closed the hood. It started to smoke when you turned the key to run or start. If so which one? [quote] It started crackling and smoking as soon as I connected the positive terminal. I never even had a chance to get into the car and turn the key. And you are right, I need to get the multimeter out and start checking. These sorts of things always start happening when there is no time or money to mess around, doesn't it? I will keep you posted. eight
Mopar or no car
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Re: fried harness again. Walk me through this.
[Re: Mattax]
#2640007
04/02/19 12:31 AM
04/02/19 12:31 AM
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Joined: Mar 2005
Posts: 1,630 North Central Florida
eightlitermopar
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In the previous thread I think you mentioned the alternator feed connection was damaged. I'd look there again. if its damaged then you know its down that line. Is something is spliced into that line? or is insulation damaged? If not, then it could be the output stud or rectifier inside the alternator is grounding.
Might do just as well with a cheap analog ohm meter rather than the test light and breaker. Disconnect the battery, then start checking for continuity to ground. Disconnect the alt, and then continue diconnecting and checking until you narrow the location, Thats how I'd do it. I did get a new alternator last time things went crazy. I will start looking around tomorrow. I know it's going to end up being something simple or stupid. eightlitermopar
Mopar or no car
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Re: fried harness again. Walk me through this.
[Re: a12rag]
#2640118
04/02/19 10:15 AM
04/02/19 10:15 AM
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Joined: Jan 2003
Posts: 10,763 North Dakota
6PakBee
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If I was a betting man I'd say you lost your alternator. It's the only failure that accounts for everything you see. What I am puzzled by is why the fusible link didn't fail and protect the rest of the harness.
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
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Re: fried harness again. Walk me through this.
[Re: 6PakBee]
#2641043
04/04/19 08:51 AM
04/04/19 08:51 AM
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Joined: Mar 2005
Posts: 1,630 North Central Florida
eightlitermopar
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If I was a betting man I'd say you lost your alternator. It's the only failure that accounts for everything you see. What I am puzzled by is why the fusible link didn't fail and protect the rest of the harness. This happened last time too. It fried the insulation on the link, but did not sacrifice the copper wire itself. This time was not near as bad as the last time it fried the wires. I will take the alternator off and test it to see if there is a short. I do have a multimeter, so how exactly should I test it to see if there is a problem with the alternator itself? eightlitermopar
Mopar or no car
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Re: fried harness again. Walk me through this.
[Re: eightlitermopar]
#2641048
04/04/19 09:02 AM
04/04/19 09:02 AM
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Joined: Mar 2005
Posts: 1,630 North Central Florida
eightlitermopar
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Also, I have a pretty busy schedule which makes this "hobby" more frustrating at the current time.
However, as I work on the car I will give updates and ask questions as I go along. One of my pet peeves is when people don't update after asking questions, so I don't want to be that guy.
If you don't hear back from me, it doesn't mean I am ignoring anyone. I will give updates on my slow progress.
Thanks again!
eightlitermopar
Mopar or no car
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Re: fried harness again. Walk me through this.
[Re: eightlitermopar]
#2641105
04/04/19 11:18 AM
04/04/19 11:18 AM
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Joined: Jan 2003
Posts: 10,763 North Dakota
6PakBee
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I Live Here
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I will take the alternator off and test it to see if there is a short. I do have a multimeter, so how exactly should I test it to see if there is a problem with the alternator itself? eightlitermopar Mattax hit the nail on the head. "If not, then it could be the output stud or rectifier inside the alternator is grounding." If it is the stud, a careful disassembly of the connector on the back of the alternator should show a problem. As to the diodes (rectifier) a resistance check to the alternator case from the output stud should show an open circuit. I am curious though, does the output wire from the alternator show any evidence of overheating at the alternator? If so, this would probably be the last nail in the coffin.
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
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Re: fried harness again. Walk me through this.
[Re: 6PakBee]
#2641184
04/04/19 02:18 PM
04/04/19 02:18 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
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As said: take off the black cable from the alt threaded stud. clamp test light clip on batt positive post. touch test light pointer to the alt stud then touch it to the cable end. NEITHER should make it light up.
live every 24 hour block of time like it's your last day on earth
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Re: fried harness again. Walk me through this.
[Re: RapidRobert]
#2641245
04/04/19 05:04 PM
04/04/19 05:04 PM
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Joined: Mar 2005
Posts: 1,630 North Central Florida
eightlitermopar
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As said: take off the black cable from the alt threaded stud. clamp test light clip on batt positive post. touch test light pointer to the alt stud then touch it to the cable end. NEITHER should make it light up. Thanks. I will try this next on Saturday and report back. I will even take pictures if needed.
Mopar or no car
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