| Slant Six Forum https://slantsix.org/forum/ |
|
| My wiring harness caught on fire this morning, why? https://slantsix.org/forum/viewtopic.php?t=34399 |
Page 1 of 1 |
| Author: | defrag010 [ Thu Mar 19, 2009 5:55 pm ] |
| Post subject: | My wiring harness caught on fire this morning, why? |
My car is 100% stock with the exception of a MSD blaster coil and HEI ignition w/ ballast resistor bypass. I've been driving it with everything like this for closing in on a year now with no problems. I was out doing some work on my car last night, I just checked the valve lash, put on a chrome valve cover w/ new gasket, and put new battery terminals on my stock positive and negative wires. Everything went great, and I drove the car around for about an hour last night. On the way home, suddenly the car's lights got real dim and the engine sputtered for a second but still ran. I shut it of, and coasted into a parking lot. I didn't see anything wrong, so I just wiggled some wires around to feel if any of them were hot. I got right back in, and the car fired right up and ran just like it should with bright lights. I drove it home and parked it, not knowing what went on. I get in this morning, and put the key in.. the motor is turning over like normal, but it's not hitting any. After about 10 seconds of cranking, all of a sudden I can smell wires and I can see smoke coming out from under the hood. The ignition/charging harness is the one that's smoked, but it's smoked from the alternator up to the firewall plug. The wire that smoked was the big dark blue wire that comes from the alternator to the ammeter, but the part on the cabin side of the firewall is just fine. Usually, it's the other way around, right? the cabin/dash part of the ammeter wiring will smoke.. but what could cause my engine harness on the side of the motor to burn itself? I have 100% stock electronics and alternator. |
|
| Author: | bigslant6fan [ Thu Mar 19, 2009 6:05 pm ] |
| Post subject: | fire |
Sounds like the field in the alternator shorted out. |
|
| Author: | SlantSixDan [ Thu Mar 19, 2009 6:45 pm ] |
| Post subject: | |
A shorted alternator field would've burned out one or both of the alternator field wires, not its output wire. Sounds like you got a nice dead short to ground somewhere in that wire between the alternator B+ terminal and the firewall. What year and model car is this? |
|
| Author: | defrag010 [ Thu Mar 19, 2009 7:37 pm ] |
| Post subject: | |
It's a '74 4door dart. I was actually mistaken, it wasn't the alternator discharge wire, it was the dark blue wire that comes off of the voltage regulator. |
|
| Author: | SlantSixDan [ Thu Mar 19, 2009 8:28 pm ] |
| Post subject: | |
Then yes, a shorted alternator field is a likely cause. |
|
| Author: | defrag010 [ Fri Mar 20, 2009 12:00 am ] |
| Post subject: | |
Would a shorted field smoke the wire that's directly attached to the alt? The smoked wire in mine started between the voltage regulator and firewall, the connector end of the wire that connects to the alternator is just fine. |
|
| Author: | defrag010 [ Fri Mar 20, 2009 1:07 am ] |
| Post subject: | |
Well, the initial theory of failure is that the hot wire shorted the two signal wires from the distributor to the HEI module. Can a short in the signal to the HEI cause it to go bad? With the alternator unplugged, the engine will start, but sound like it's running on 3 cylinders and you have to give it like 1/4 throttle to keep it running. With the alternator plugged in, it does the exact same thing only the lights get brighter when the engine sputters. It's late and I'm done for the night, but it almost seems like there is either a problem with the signal to my HEI, the HEI module itself, or my plugs are on in the wrong order.. |
|
| Author: | Charrlie_S [ Fri Mar 20, 2009 5:36 am ] |
| Post subject: | |
I would check and make sure you didn't get a wire pinched under the valve cover when you installed it. That can happen very easily. |
|
| Author: | defrag010 [ Fri Mar 20, 2009 8:20 am ] |
| Post subject: | |
I've already pulled, repaired, and installed the harness last night and I just got done driving the car to go get some breakfast, so nothing is wrong anymore. I'm just wondering what could cause this. I was confident in the car up until the wiring spontaneously combusted. I'm moving from Houston to Tulsa this summer and was planning on driving the dart all the way there, but I'd be screwed if a wire randomly burnt up halfway between Houston and Dallas. 
|
|
| Author: | KBB_of_TMC [ Fri Mar 20, 2009 9:57 am ] |
| Post subject: | |
Older Mopar alternators use easily removed brushes; sometimes the plastic insulators can break and the brush & spring fall out of place and short out, but I've never heard of one fixing itself. I suppose it could have fallen further and then un-shorted... |
|
| Author: | defrag010 [ Fri Mar 20, 2009 1:39 pm ] |
| Post subject: | |
Yeah, I know there is nothing wrong with the alternator because it has never shown any signs of any kind of problem... it was something within the wiring harness, maybe some circuit that needed a smaller fuse or something.. I got the car in October of 2007 and I haven't had one electrical problem at all. Things changed when I put the new battery terminals on and the electrical system appeared to be stronger due to the better connection to the battery. Am I the only one who has had a stock car burn up a harness? |
|
| Author: | Aggressive Ted [ Sun Mar 22, 2009 11:06 am ] |
| Post subject: | |
My 74 engine harness started to burn but caught it in time. The big blue wire had gotten hot so the enamel melted off and was touching the oil lamp wire. It melted about 6" or so and was pretty hot! It sure stunk..... I bought new stock Mopar connectors and some wire and rebuilt the bundle one wire at a time. Take a look at the link below and you can see I added some coated hose clamps along the lower side of the valve cover to run the wire bundle through so it can't short out. |
|
| Author: | SlantSixDan [ Sun Mar 22, 2009 11:33 am ] |
| Post subject: | |
You're definitely not the only one. Did I ever tell the story of when I burned out the wiring harness in my (then my dad's) '62 Lancer…right in front of him? Looks like I did (and the linked thread is worth reading, on the topic of adding and repairing circuit protection). |
|
| Author: | Rug_Trucker [ Thu Mar 26, 2009 5:45 am ] |
| Post subject: | |
The battery wire to my alternator in my van burned in the snap together connector. I replaced it with a solid wire, heavier gauge than stock. Then extra insulated it with a piece of fuel line. |
|
| Page 1 of 1 | All times are UTC-07:00 |
| Powered by phpBB® Forum Software © phpBB Limited https://www.phpbb.com/ |
|