Wiring question

S

Steven Mikael Goupil

Hi, everyone-I was wondering if I could get any thoughts/recommendations on the wiring in my MM 1963 Duplex? The old girl has been through the ringer and I've spent the last few years collecting pieces for her resto but I keep hitting a wall on her wiring. I can't find anyone who has series 75 repro dash or engine wiring. I have a nice set from a limo of the same year but would like to have it restored or repro'd since it's 50 years old but none of the guys doing resto wiring seem to want to touch the 75s. She now has what I like to call magical mystery wiring-never know when it's going to work properly so replacing is a must.
Thanks so much in advance for any ideas!
 
American Auto Wire makes wiring harness's for GM cars. I just checked their website, and they specifically exclude the series 75 cars. I have been told that if they have the original drawings for the car model from GM, that they have the capability to reproduce it. It might take some arm twisting to get them to do it. Unless your old wiring is cut up, I would be inclined to believe that it is still good. I have had no problems with the wiring in my 1962 Chevrolet, or my 1963 Chrysler. My personal experience has been that if the wiring hasn't been tampered with (i.e. cut), then it will be just fine, as long as it hasn't been subjected to extreme moisture or the desert sun. Even the wiring in my 1969 Cadillac that came from the high desert area of Oregon, and then went to the very damp state of Washington has no wiring problems.
 
Wiring advice

Steven Mikael Goupil said:
Hi, everyone-I was wondering if I could get any thoughts/recommendations on the wiring in my MM 1963 Duplex? The old girl has been through the ringer and I've spent the last few years collecting pieces for her resto but I keep hitting a wall on her wiring. I can't find anyone who has series 75 repro dash or engine wiring. I have a nice set from a limo of the same year but would like to have it restored or repro'd since it's 50 years old but none of the guys doing resto wiring seem to want to touch the 75s. She now has what I like to call magical mystery wiring-never know when it's going to work properly so replacing is a must.
Thanks so much in advance for any ideas!
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Over the years 60s GM wiring has not been troublesome I think you are worried where there is not an issue. The main thing is check for bare wires tape or shrink tube them. Clean plugs with a good contact cleaner. Check where wires are running along the floor for bear spots and corrosion. Check fuse box for corrosion around fuses again clean with contact cleaner. If you are splicing in new wire in DO NOT use butt connectors splice solder and tape connections butt connectors are not reliable,they corrode and pull apart. You have a Coach not an ambulance so there is not much of a load on the wiring and not alot of lights bells and whistles. If you want to cover your butt install a circuit breaker or high amp fuse in the main body feed line from the battery then if a short does occur no need for the fire department.If "experts" have been there then use a Cadillac wiring diagram remove the cobbled in wiring and replace wires as needed to conform to the Cadillac diagram GM did know what they were doing in your era. I have a 62 75 series limo in the yard that ran and drove when parked but removal is an issue and I still do not think a replacement harness is in order. Good luck with the project. Pete
 
Thank you so much, Daniel,Paul and Peter- I really appreciate your help. The wiring I have should be good-I bought it from a gentleman who pulled it from a 63 limo and he's pretty reputable. Being pretty ignorant on wiring issues, do you know if there's any companies that would be willing to test it before I install?
As Peter said, she doesn't have any bells & whistles (figuratively and literally) like an ambulance and I wouldn't think she would be any greater power draw than a series 62 which is why I'm surprised those repro sets won't work-but again, my knowledge is extremely limited!
BTW, Paul, we have similar stories about our coaches- mine came from the Arizona desert and was brough here to Washington. She was left in the rain in a field somewhere in Tacoma but luckily someone had the sense to save her-now I have most of the parts to restore her-just a slow process!
Thanks again for the great info!
 
what is the problem with the wiring in the coach?? as Peter said unless you have had a major fire simple repairing what you all ready have is best. it takes no more time and most everything you do will be only on the ends. I will warn you that depending on who built you coach the harness will have some differences between the 75 and the other manufactures. you will not gain any things specific to the manufactures that built yours with a GM harness. in those years they are not much of a harness under the dash but rather a basket of wire.
 
Thanks, John- My wiring issue is pretty extensive. My coach was abused pretty good-aside from the rust and cosmetic issues, one of the last owners blew her original engine and let her sit in the rain for a few years. The last owner had a pontiac engine and tran dropped in and I think in the process clipped or tore out some of the original stuff and rigged up his version. I'm going to give Peter's suggestions a shot and see what happens with the replacement stuff I have. It did come from another MM 63 Limo so it probably even has a few more extra wires for things such as power windows that I don't have.
Thanks so much for everyone's input! Nice to have true procar guys give me some insights!
 
from what you describe all you need would be from the fire wall forward. of the factory wire harness. sorry I miss what after market manufacture you were working on. but there stuff would be run separate from the GM harness in the engine room. how the under dash and rear was done is not GM by at least 50%. if you do replace under dash be careful to leave the after market people wiring alone and only do the GM stuff. but unless you have had a fire I have never found it necessary to change a harness under the dash. firewall forward yes. but never under the dash.
 
Hi, John- I have another under dash harness just in case but maybe you're right and the problems are in a different section of wiring. Right now nothing seems to work beyond running lights. I had the wipers come on once but never again so I don't know if the motor is bad or the wires. When she was bought after sitting for years they replaced her blown engine with a Pontiac and were indescriminate in what they cut or chopped to fit the engine in. I've got another 390 GM and matching tran to drop in (from another 63 hearse yet!) after I get it rebuilt and at that time I plan to do all the wiring. I'm not proficient in mechanics so this is all new to me but I'm willing to do the work.
Thanks so much for your help!
 
The under hood wire harness is the same as the passenger car wire harness. The under dash harness is probably mostly the same, and I doubt that much was hacked under the dash, other than possibly radio wiring.
 
I bought the under hood wire harness from USA auto parts for my Fleetwood 75 and it all plugged in just fine and everything worked just fine. mine had been ripped out of the car by the last owner when they pulled the motor out of the car I had no choice but to by a new one because the old one was gone Its nice to have wires not spliced or retape up
 
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