Well, came home via a ride. Truck died on the side of the road. (new alt is in the passenger seat...) Fuse block bellowed smoke and melted fuse, didn't pop it though. Melted the YR wire back about 6 inches.
I double checked and the YR wire goes to the instrument panel, etc, AND oil pressure switch. I just replaced the oil pressure switch last night. Could it caused the problem? Bad sending unit?
BAD oil pressure switch cause meltdown???
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fastboatman29212
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Re: BAD oil pressure switch cause meltdown???
Sorry about the bad news! Really sorry! I cannot believe the oil pressure switch could cause any electrical damage. (But maybe I'm about to learn something.) Is this gonna be a tough repair? Sounds like you might be able to repair the fuse box, right?
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Rev_D21
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Re: BAD oil pressure switch cause meltdown???
Must keep the dually alive, let us know how we can help and what parts you might need to fix it.
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N-Dually
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Re: BAD oil pressure switch cause meltdown???
Thanks guys! I wouldn't think a oil pressure switch could do that either!!!
I am home now and the dually has a shiny new alternator. The battery light stayed on all the way home, but when I put the DVM on the battery, it showed good at 12.9 and the alt was putting out 14.1v.
Brake for dinner and then off to look at the wiring.
I wish I could get more info on a situation like this. It was actually kinda scary. What if the fuse box was somewhere else and I wouldn't have noticed the smoke?
I will only put a 10 amp (preferably 5 amp) fuse back in the circuit. I will have to put in an inline fuse for now. I see a trip to pull-a-part in the near future!
Stay tuned...
I am home now and the dually has a shiny new alternator. The battery light stayed on all the way home, but when I put the DVM on the battery, it showed good at 12.9 and the alt was putting out 14.1v.
Brake for dinner and then off to look at the wiring.
I wish I could get more info on a situation like this. It was actually kinda scary. What if the fuse box was somewhere else and I wouldn't have noticed the smoke?
I will only put a 10 amp (preferably 5 amp) fuse back in the circuit. I will have to put in an inline fuse for now. I see a trip to pull-a-part in the near future!
Stay tuned...
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N-Dually
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Re: BAD oil pressure switch cause meltdown???
OK, I don't think it is the oil switch, though it is odd that it did it the very first drive after swapping it for a new one. Yellow wires are for instrumentation. Makes sense since the fuel and temp gauges are now dead.
I traced the YR wire from the fuse block to what appears to be the lighting harness that goes to the back of the truck. I did stop at the engine because it got late. I found melting and discoloration on the YR wire all the way to where I stopped at the engine. I will start the hunt back tomorrow. Anyone know about this? Any help would be great!
On a side note. We all agree that my truck is a 1986, even says it on the title and VIN look up. According to the Haynes book, via the fuse block schematic, it is a 1985. Odd huh?
I traced the YR wire from the fuse block to what appears to be the lighting harness that goes to the back of the truck. I did stop at the engine because it got late. I found melting and discoloration on the YR wire all the way to where I stopped at the engine. I will start the hunt back tomorrow. Anyone know about this? Any help would be great!
On a side note. We all agree that my truck is a 1986, even says it on the title and VIN look up. According to the Haynes book, via the fuse block schematic, it is a 1985. Odd huh?
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PEZi
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Re: BAD oil pressure switch cause meltdown???
Well... '86 was technically the hardbody start year... all 720's were produced in or before '85 regardless, so not too weird.
As far as your problem... never heard of it before... but I am starting to get better at wiring crap. Let me know what you find!
As far as your problem... never heard of it before... but I am starting to get better at wiring crap. Let me know what you find!
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Rev_D21
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1996 D21 Reg 4WD 5Spd
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Re: BAD oil pressure switch cause meltdown???
1986.5 was the technical start of the HB.
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N-Dually
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Re: BAD oil pressure switch cause meltdown???
Ok. All is good. Once again, I am not going to blame the truck for the problem. What? Of course there is someone to blame! Who you ask? The previous idiot owners. 
First the electrical issue: After tracing the YR wire, I discovered that it was melted from the fuse block all the way back to the back up lamp switch on the transmission. It was not connected though. The YR wire had an exposed end connector, which I am guessing shorted out on the transmission housing. Since it was not being used, I just removed the wire all together. Now, the reason the instrument cluster was not working is because it, along with the hazard relay, and the tach plug all feed off the same wire. For some reason those wires where not destroyed - Thank God!
I was able to clean up the fuse block and reuse the same socket that had melted a bit. I am now using a 10 amp fuse instead of the 15 amp.
I also took apart the harness by the battery. Cleaned the wires and re-taped what was falling apart and taped what needed to be. Looks much better!
Here is the freebie... The junction where all of those segments of wire join is located inside the main harness (the biggest bundle), just to the left of the steering column. Should I post this in another post with an appropriate heading?
As for the alternator, again, not blaming the truck. There is no telling how long the P/S reservoir leaked on it before I fixed it. And besides, I think the alty did pretty good for 25 years!
Off to swap out thermostat and a belt. I hope to remove the old carb tonight!
First the electrical issue: After tracing the YR wire, I discovered that it was melted from the fuse block all the way back to the back up lamp switch on the transmission. It was not connected though. The YR wire had an exposed end connector, which I am guessing shorted out on the transmission housing. Since it was not being used, I just removed the wire all together. Now, the reason the instrument cluster was not working is because it, along with the hazard relay, and the tach plug all feed off the same wire. For some reason those wires where not destroyed - Thank God!
I was able to clean up the fuse block and reuse the same socket that had melted a bit. I am now using a 10 amp fuse instead of the 15 amp.
I also took apart the harness by the battery. Cleaned the wires and re-taped what was falling apart and taped what needed to be. Looks much better!
Here is the freebie... The junction where all of those segments of wire join is located inside the main harness (the biggest bundle), just to the left of the steering column. Should I post this in another post with an appropriate heading?
As for the alternator, again, not blaming the truck. There is no telling how long the P/S reservoir leaked on it before I fixed it. And besides, I think the alty did pretty good for 25 years!
Off to swap out thermostat and a belt. I hope to remove the old carb tonight!
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fastboatman29212
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Re: BAD oil pressure switch cause meltdown???
HoooRay for Dually!!! You sure know your way around wiring problems. It would have taken me 2 weeks.
I once installed a new 1157 tail light bulb and the same day when I turned on my headlights, my dash lights went out. Fuse blew. Didn't know why but no biggie, I'll just fix it when I get home. Took me 4 days and 10 fuses later to figure out that the BRAND NEW BULB outa the package was defective from the factory and was shorting out my fuses. Never occurred to me a bulb could be bad from the factory. LOL! I'm just glad I didn't push it off a cliff!
I once installed a new 1157 tail light bulb and the same day when I turned on my headlights, my dash lights went out. Fuse blew. Didn't know why but no biggie, I'll just fix it when I get home. Took me 4 days and 10 fuses later to figure out that the BRAND NEW BULB outa the package was defective from the factory and was shorting out my fuses. Never occurred to me a bulb could be bad from the factory. LOL! I'm just glad I didn't push it off a cliff!