VCCA Home Forums TECHNICAL - GENERAL Electrical - 12 volt 12 volt conversion gone haywire

Well, I got around to joining the VCCA. I am in Wisconsin and my running 1950 is in Georgia. I am up here for the summer pillaging parts from my rust-bucket 50 to take South in the fall. I am keeping busy trying to figure out the wiring diagram so I can install the new fuse box and harness this fall. (I need to change a few of the names) If you have a chance, check out the diagram I put on my photo page and let me know if I have missed anything. As with any of my "works in progress" I am open for any suggestions. (Lots of extra wire LOL) Thanks guys.

https://vcca.org/photos/alumni/gallery/67334111/med_20210619_150359_17253.png

When doing the 12 volt conversion, you may want to keep the same wire gauge as the 6 volt setup. The 6 volt is a heavier gauge and you’re less likely to burn up your wiring as the 12 volt system will be higher voltage, lower amperage. Just my 2 cents worth.

Thanks for the 2 cents. You can add a nickles worth if you want to. I'll take all the help I can get. Using mostly the same gauge wire. Using some that is heavier because that is the gauge wire that I have on hand. Like the "main hot" wire, going from 8 to 6 because I found a half roll of 6 Gauge. Also putting in a maxi fuse in this wire is more for my convenience. It should never blow unless something catastrophic goes on, but, I can just pull the fuse and cutoff all the electricity to everything to fix, add or whatever I need to do.

It appears that you are re-engineering the circuitry for this car rather than repairing and replacing the stock harness.

In that case the key advice is to work one circuit at a time. Remember that there interactions especially in the lighting. For example, brake lights and turn signals are the same filaments in the rear bulbs

I am forced into the "re-engineering" part. Some wires, the insulation is bad. Other wires have the insulation gone and getting a few situations where we are getting smoke from the dash. instead of replacing most of the wires and fixing others, I am just putting in all new. It may be a bit more than I need to do, but I would rather have something I can rely on.

If the wiring is losing the insulation I would start at the battery and replace ALL wiring. It will end up cheaper that way than burning the car to the ground when you miss a short circuit.
Tony

That's what is going to happen. All new, and in some cases improved.

Here is my two cents. In my personal 52 Styleline I put in an American Autowire Power Plus 13(all American Autowire kits are GM based). I had to change a few things like bypass the push button for starting. I used an original 63 Impala ignition switch housing and used my original tumbler. I converted all lights to LED EXCEPT headlights which are still halogens. What a change it made reading the gauges with LED now. I had to change the flashers to low wattage flashers. I am still buttoning up some loose ends like getting the gas gauge to work. Just started that project today at lunch at my first job. I will keep you informed how that gets wired. I have seen ebay wire harnesses and the wire gauge is smaller then safe in my opinion. I have used other brand names and some are pretty tough to understand if wiring isn't a second language. I wire old cars at all 3 of my jobs. I have had great success using American Autowire no matter which kit you get. Oh and their technilcal support is very helpful.

A question for all of you who have done a 12V conversion and speak "auto electric":

What wires do I need to swap/reroute /connect together from the original voltage regulator? Also, when Williamson's restored the gauges, I asked them to replace the ammeter with a 12V voltmeter, which makes more sense with an alternator. Since I will be removing the ammeter from the circuit, do I just connect together the wires originally connected to the two posts of the ammeter?

NOTE: before anyone asks, my '52 Fleetline has a reproduction wiring harness that is in practically brand-new condition, so no worries about bare wires and rotted insulation here.

Thanks in advance for any and all help.

It probably would help to get a separate topic going on this. I’m pretty confused how your conversion relates to all the other posts in this thread.

There are boatloads for posts about 12 volt conversions. My guess is that you are also replacing the generator with a one wire alternator. Just Google “replace generator with one wire alternator”.

You can connect the ammeter wires together so the current will still pass to the rest of the electrical system.

You can also run a wire from that connection to the + side of the voltmeter. Then ground the voltmeter with either a jumper wire from the - terminal or possibly through the mounting bracket.

Yes.

An ammeter is electrically equivalent to a piece of wire.

Thanks Rusty. Also, you are correct -- I should have begun a separate post.

bloo, thanks for the confirmation. This is what I suspected, but I wanted to be certain before I did something stupid!

OK, I got back down to Georgia and back my my 1950. Started to take out burnt wires and will be replacing everything. The dash light sockets have all the insulation gone from the wires. The only replacements I have found are for the Trucks (1947 to 1966 to be exact). They look like they will fit, but, looks can be deceiving. I also think that they would have used the same for the cars and the trucks up to at least 1955. Does anyone have first hand knowledge if they will fit? Thanks again... Jeff

PS: I would like to replace all the light sockets with new. Does anyone have a cross reference to get the right sockets that will fit into the "places" where they belong. Thanks again, again.

Well, life got in the way but wiring is done. Not many pictures as only a few wires are visible. You can check out how the wires ended up in the photos under "1950 Styleline Wiring Diagram". Learned a few things along the way. #1 You can resting wires going to the trunk along the roof by using a fish tape and start from the trunk and CAREFULLY pushing it from the trunk up the right side and along the roof/door line and come out under the dash. I had to do this because I broke the original wires and could not use them to pull new ones through. #2 The dash lights sockets from the pick-ups (1947-66 Dash Pigtail Socket) will work in the car. One place I contacted said they would only work on the pick-ups, but I had no problem. #3 The front turn/parking light sockets can be replaced with the newer style sockets. I think these were from the 60s. They are all metal and have more "gripping wings" on them, but they will work. #4 Again on the front turn/parking light sockets, I could not get a good ground. So what I did was solder a ground wire to the outside of the new medal sockets and attach it to a good ground. #5 One thing I always had problems with GMC products was the grounds. The battery is grounded to the engine. I added extra ground wires from the battery to the body under the hood and another one under the dash. I hope this will solve all grounding problems. #6 J.B. Weld is an insulator. I made an accessory block by using Plexiglas bolts and J.B Weld (I will try to get and post a pick). How I did it is cut 2 pieces of 1/8" plexiglass 1"x 2-1/2". One plexiglass piece I drilled two 3/16" holes (1/2" from each end) and put #10 bolts through. Before putting the bolts through. I ground off about 1/3 of one side to keep it from turning. You will see why in a minute. The 2nd piece I drilled two 3/8" holes to fit the bolt heads into. Sandwiched between the plexiglass is also a flat piece of aluminum to connect the two bolts. I then glued the 2 pieces of plexiglass together and filled the 3/16" holes with J.B. Weld. I then attached this under the dash with #6 screws to use as a positive accessory block. Learned a lot more but these are the "hi lights" I remember now.

After all this EVERY wire is new and is fused. The only thing that does not have a fuse is between the alternator and the battery. I left this "un-fused" because I do not think it needs one and I don't think there was a fuse here until cars in the late 1970s or early 1980s. Added a drawing of the Acc Block.

Glad you got it sorted out! :)

Only a few "little" problems. I had a dead short in the wipers. Had a piece of sheet metal touching the switch. Put rubber tape around and I moved the switch a bit. Gas Gauge did not work. New sending unit.The Amp meter showing discharge when charging. Switched wires. She is on the road again for a while. Next project is putting in the 235. Thanks for all the help from everybody!

As someone who has recently started on a 1940 KC model pickup project and was about to ask this community if I should convert to 12 volts or not...this thread is amazing!

I don't know if I have figured out the answer, but there was a lot of interesting reading here.

The truck I am starting on has an alternator and a starter, but I don't know anything about them. There is not one usable wire in the whole truck, so rewiring will have to happen. I have rewired a couple of old vehicles in the past, but that was decades ago, so I will probably purchase a wiring harness from one of the vendors.