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Converting 12volts back to 6


Guest Jonny88

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Guest Jonny88

Hi guys, The car is finally paid off and I am ready to start my restoration on the 1951 Oldsmobile Super 88 that I talked about in other post.

The first item that I want to deal with is the electrical system. The car currently is converted to 12 volts but I think it was only done for the starter but the strange part is that the headlights and one tail light work, everything else including all gauges but amp do not work, turnsignals dont work, heater does not work, horn does not work, radio does not work, wipers dont work.

If you guys could help me I would greatly appreciate it, I dont know were to start.

I did already buy a 6volt original AC Delco Generator correct for the time period, but dont know what else I will need to get aside from the 6v bulbs for electrical.

Thanks

Jon

1951 Oldsmobile Super 88

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hi jon, if you have only one taillight working, and you know the bulb is good, then you have either a bad ground or a break in the wire that send voltage to that bulb. there's one wire going from the headlight swith to where the one wire splits into two. but you need to get the wiring diagraham for your olds, i'm sure someone in the olds forum, or olds clubs can help you get one. it sounds like to that whoever change the olds so that it would start on 12 volts, meant to leave disconnected the power source for the fuse block, that pretty much everything you listed as not working has a fuse there in the fuse block for protection. charles coker, 1953 pontiac tech advisor.

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Guest Jim_Edwards

Jon converting back to a 6V system will require you get a full grip on exactly what was done with the 12V conversion, because you're going to have to undo it step by step; assuming you really want to reverse the conversion. Anything and everything that was changed to work on 12V will have to be identified and changed unless there was some sort of voltage step down scheme done for everything but the starter and charging circuit. You'll need an original 6V voltage regulator to go with that 6V generator and obviously a new battery if you choose to pursue the change back to 6V. I'm going to predict you'll also be replacing tail lamps, head lamps, and maybe all the miniature bulbs in the dash. You may need to look for resistors that might have been used with gauges and the fuel sending unit.

If you are unsure about what has been done, it might be a good idea to pay some guy from an auto electric shop to come by take a look after you get a copy of the correct wiring diagram. He should be able to immediately determine mods that were done to take it to 12V.

Jim

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  • 2 weeks later...
Hi guys, The car is finally paid off and I am ready to start my restoration on the 1951 Oldsmobile Super 88 that I talked about in other post.

The first item that I want to deal with is the electrical system. The car currently is converted to 12 volts but I think it was only done for the starter but the strange part is that the headlights and one tail light work, everything else including all gauges but amp do not work, turnsignals dont work, heater does not work, horn does not work, radio does not work, wipers dont work.

If you guys could help me I would greatly appreciate it, I dont know were to start.

I did already buy a 6volt original AC Delco Generator correct for the time period, but dont know what else I will need to get aside from the 6v bulbs for electrical.

Thanks

Jon

1951 Oldsmobile Super 88

A lot of times the person doing the conversion to 12V does not change 6V bulbs, and they will burn out eventually. Same goes for horn relay. As I recall, the oil pressure gauge is mechanical, therefore this should work. The ammeter doesn't matter as it is current sensitive and not voltage sensitive. The fuel and temp gauges are 6V and might have been fried.

The heater motor may have been burned up, or possibly the heater fan switch is burned up.

Wipers are vacuum if still original and have no electrical connections.

Turn signal flasher is probably gone too. Radio vibrator probably got cooked too or the fuse is blown.

I would get a diagram and go through bulbs, flasher, and fuses first and see what you come up with. If you do this first, you can get a handle on this and restore at least the electrical.

Last bit of advice, check the ignition coil and see if a ballast resistor is installed. If no resistor and a 6V coil, then the engine probably doesn't run to good either. You won't need the ballast resistor with a 6V coil.:)

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  • 2 weeks later...
Guest Jonny88

I did some more investigating with this electrical mess last weekend. I noticed after getting under the dash that the gas gauge and water temp gauge both are disconced from the dash! That means the previous owners had some idea of what they were doing. Thats two gauges that I will not have to change. You guys are right about the volts and oil temp, they still work fine. The radio, I looked at it, did not examin too closly but will this weekend when I get home. If it is not disconced then it will be fried as you stated above. I did find an original replacement for 200 dollars on ebay, thats alittle high, but it works and has been restored by the seller. I did not check the heater at all but will this weekend as well. The wipers are vacumm driven and I found the vacumm motor, the arms that connect to the outer unit on the windshield were disconnected, intresting. I will first attempt to change the right tail light that was burnt out, with a 12v one, then go from there. I do have the original service manual with all the wiring diagrams, a tool that I have been using since I got the car. Cant find the horn relay for the car yet, im guessing that it is in the engine bay somewere on the cowling. The high and low horns for the car are gone, looked were I was suppose to according to the diagram and they were not there. Will have to find replacements. The turn signals do not work, THE WEIRD Part, when you pull the lever up as if making a right turn, the signal makes the clicking sound but nothing else. I am nervous to keep trying it, if it is still conected without a step down resistor then I will eventually blow it. Nothing else on the turn signals work. It will be a job. Thanks guys for youre responses and let me know if you have any more suggestions, I will be back of course. Appreciate your help. thanks

Jon

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