# Positive or negative ground **URL:** \ **Category:** General Discussion\ **Tags:** f250, ford\ **Created:** [March 15, 2020, 12:56pm UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072 "2020-03-15T12:56:06Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Bruceparts\_165172](https://avatars.discourse-cdn.com/v4/letter/b/7ba0ec/32.png) [@Bruceparts\_165172](https://community.cartalk.com/u/Bruceparts_165172)\ **Post date:** [March 15, 2020, 12:56pm UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/1 "2020-03-15T12:56:06Z")
Hi. Im restoring a 1953 Ford F250, 239 Flathead. Installing a new wiring harness. When i got this truck, i got it running snd everything works fine. All electrical, wipers, lights, etc work as they should. (It’s 6V) My question is, the battery was installed with the - negative cable to ground, positive to starter solenoid like modern vehicles are. BUT, the wiring diagram shows it with a POSITIVE GROUND. Do i change it back to positive ground? Will that screw anything up?? Thanks. ---
**Author:** ![COROLLAGUY1](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/corollaguy1/32/7575_2.png) [@COROLLAGUY1](https://community.cartalk.com/u/COROLLAGUY1)\ **Post date:** [March 15, 2020, 1:18pm UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/2 "2020-03-15T13:18:04Z")
If the vehicule starts and work as it should your set-up is fine.Leave it like it is. ---
**Author:** ![Purebred](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/purebred/32/46796_2.png) [@Purebred](https://community.cartalk.com/u/Purebred)\ **Post date:** [March 15, 2020, 2:52pm UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/3 "2020-03-15T14:52:00Z")
Keep it negative ground. I would suspect radio and gauges are setup for negative ground since the truck was negative ground when you started. ---
**Author:** ![Triedaq](https://avatars.discourse-cdn.com/v4/letter/t/65b543/32.png) [@Triedaq](https://community.cartalk.com/u/Triedaq)\ **Post date:** [March 15, 2020, 4:20pm UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/4 "2020-03-15T16:20:38Z")
I am surprised everything works. Your vehicle was originally 6 volt positive ground. I bought a 1948 Dodge back in 1977. The battery had been installed with the negative terminal attached to the chassis. The ammeter gauge read backward, but everything else worked, although I didn’t try the radio. To correct the problem, I discharged the battery completely and then brought it back up with a trickle charger. I repolarized the generator. This is a simple operation. I think I momentarily shorted the battery terminal on the voltage regulator to the field coil, but I am not certain about this. There were two different methods to repolarize the generator depending on whether the field coil in the generator was externally grounded or internally grounded. I have repolarized both types of generators, but I don’t remember which is which. You might be able to find a the book in a library titled “Fix Your Ford” by Bill Toboldt. If your truck now has an alternator or has a transistor radio, don’t change it. My 1948 Dodge had a generator and vacuum tube radio. ---
**Author:** ![kurtwm1](https://avatars.discourse-cdn.com/v4/letter/k/13edae/32.png) [@kurtwm1](https://community.cartalk.com/u/kurtwm1)\ **Post date:** [March 15, 2020, 4:28pm UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/5 "2020-03-15T16:28:56Z")
I feel different. I would change it to factory original. The radio, lights, wipers will work regardless of polarity. However, if you have sensors they may or may not work correctly. ---
**Author:** ![Triedaq](https://avatars.discourse-cdn.com/v4/letter/t/65b543/32.png) [@Triedaq](https://community.cartalk.com/u/Triedaq)\ **Post date:** [March 15, 2020, 4:56pm UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/6 "2020-03-15T16:56:04Z")
@kurtwm1. I don’t think a 1953 Ford truck had sensors. It probably has vacuum wipers. I would even bet that the oil pressure gauge may be mechanical. The temperature gauge may be electrical. It seems to me that on Ford products of that vintage, the temperature gauge went to hot when the ignition key was turned off. There were no oxygen sensors as there was no catalytic converter. There was no PC valve. There was a road draft tube to ventilate the crankcase. I am glad the flathead engine is still in the OP’s truck. Like the South, the flathead will rise again! ---
**Author:** ![VOLVO-V70](https://avatars.discourse-cdn.com/v4/letter/v/8e8cbc/32.png) [@VOLVO-V70](https://community.cartalk.com/u/VOLVO-V70)\ **Post date:** [March 15, 2020, 5:15pm UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/7 "2020-03-15T17:15:44Z")
> [@kurtwm1](#): > > However, if you have sensors they may or may not work correctly. Sensors on a 1953 Flathead ? ---
**Author:** ![Purebred](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/purebred/32/46796_2.png) [@Purebred](https://community.cartalk.com/u/Purebred)\ **Post date:** [March 15, 2020, 9:54pm UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/8 "2020-03-15T21:54:34Z")
The question I have is: Are you restoring to factory original or as a fun weekend driver with occasional display at local car shows? If the latter, you might even consider going to 12 volt negative ground, that does require replacement of bulbs, radio, gauges, etc. If the former, then back to positive ground for the purists. ---
**Author:** ![keith](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/keith/32/5518_2.png) [@keith](https://community.cartalk.com/u/keith)\ **Post date:** [March 15, 2020, 9:59pm UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/9 "2020-03-15T21:59:51Z")
If the radio works, leave it alone. The tubes in these old radios require a certain polarity and it can’t be changed, unless you want to rewire the whole radio. If you don’t have a radio in it, then you can leave it or put it back. I once had a 1960 Borgward with a 6 volt positive ground. No radio. I changed it to negative ground just so I could jump start it from friends cars. To compensate for the difference in voltage, we would touch bumpers and use only one battery cable. ---
**Author:** ![kurtwm1](https://avatars.discourse-cdn.com/v4/letter/k/13edae/32.png) [@kurtwm1](https://community.cartalk.com/u/kurtwm1)\ **Post date:** [March 15, 2020, 10:00pm UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/10 "2020-03-15T22:00:34Z")
> [@VOLVO\_V70](#): > > Sensors on a 1953 Flathead yes, despite popular believes there are sensors, i.e. overheat temperature sensor. ---
**Author:** ![Ronnie\_Gregory](https://avatars.discourse-cdn.com/v4/letter/r/e19adc/32.png) [@Ronnie\_Gregory](https://community.cartalk.com/u/Ronnie_Gregory)\ **Post date:** [March 15, 2020, 10:20pm UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/11 "2020-03-15T22:20:39Z")
My dad always told me if it ain’t broke don’t fix it​:grin:👍 ---
**Author:** ![old\_mopar\_guy](https://avatars.discourse-cdn.com/v4/letter/o/6bbea6/32.png) [@old\_mopar\_guy](https://community.cartalk.com/u/old_mopar_guy)\ **Post date:** [March 15, 2020, 10:40pm UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/12 "2020-03-15T22:40:58Z")
If the starter is now set up to spin the engine in the correct direction (clockwise) as is, reversing the polarity will cause the starter to spin the engine backwards ( unless the overrunning clutch prevents it from transmitting torque in the “wrong” direction. I can’t wrap my head around the physics tonight). ---
**Author:** ![Triedaq](https://avatars.discourse-cdn.com/v4/letter/t/65b543/32.png) [@Triedaq](https://community.cartalk.com/u/Triedaq)\ **Post date:** [March 15, 2020, 11:24pm UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/13 "2020-03-15T23:24:35Z")
On my 1948 Dodge, the starter spun the correct direction no matter which way the battery was connected. ---
**Author:** ![wentwest](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/wentwest/32/6073_2.png) [@wentwest](https://community.cartalk.com/u/wentwest)\ **Post date:** [March 15, 2020, 11:25pm UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/14 "2020-03-15T23:25:02Z")
It seems to me I remember electric motors running in the opposite direction if you reversed the polarity. ---
**Author:** ![old\_mopar\_guy](https://avatars.discourse-cdn.com/v4/letter/o/6bbea6/32.png) [@old\_mopar\_guy](https://community.cartalk.com/u/old_mopar_guy)\ **Post date:** [March 16, 2020, 12:02am UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/15 "2020-03-16T00:02:08Z")
I actually have a starter from '48 Dodge on the garage ( along with lots of other parts, I’ll play with it tomorrow). ---
**Author:** ![old\_mopar\_guy](https://avatars.discourse-cdn.com/v4/letter/o/6bbea6/32.png) [@old\_mopar\_guy](https://community.cartalk.com/u/old_mopar_guy)\ **Post date:** [March 16, 2020, 12:03am UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/16 "2020-03-16T00:03:29Z")
In theory you are correct. I’ll test that out tomorrow. ---
**Author:** ![kurtwm1](https://avatars.discourse-cdn.com/v4/letter/k/13edae/32.png) [@kurtwm1](https://community.cartalk.com/u/kurtwm1)\ **Post date:** [March 16, 2020, 12:48am UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/17 "2020-03-16T00:48:48Z")
That is correct, the starter motor is a DC motor and will spin the opposite direction if OP connected the positive battery to ground. HOWEVER, if OP also reversed polarity (flipped + & - wires around) on the starter than all would be fine and the starter would spin in hte proper direction. ---
**Author:** ![Bruceparts\_165172](https://avatars.discourse-cdn.com/v4/letter/b/7ba0ec/32.png) [@Bruceparts\_165172](https://community.cartalk.com/u/Bruceparts_165172)\ **Post date:** [March 16, 2020, 1:59am UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/18 "2020-03-16T01:59:45Z")
I’ve got the starter on the bench. I’ll give it a try. The guages worked, but the charge indicator didn’t. The heater did, though, and it looks like the wiring was never altered. So i dont know. No radio, so thats not a problem. ---
**Author:** ![kurtwm1](https://avatars.discourse-cdn.com/v4/letter/k/13edae/32.png) [@kurtwm1](https://community.cartalk.com/u/kurtwm1)\ **Post date:** [March 16, 2020, 4:16am UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/19 "2020-03-16T04:16:43Z")
> [@Bruceparts\_165172](#): > > but the charge indicator didn’t. of course not, the needle wants to go in the opposite direction. Flip the connecting wires around and I bet it works. Better start noting changes on your diagram, you might need that in the future. ---
**Author:** ![It\_s-Me](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/it_s-me/32/12660_2.png) [@It\_s-Me](https://community.cartalk.com/u/It_s-Me)\ **Post date:** [March 16, 2020, 11:32am UTC](https://community.cartalk.com/t/positive-or-negative-ground/161072/20 "2020-03-16T11:32:40Z")
> [@kurtwm1](#): > > if OP also reversed polarity (flipped + & - wires around) on the starter than all would be fine and the starter would spin in hte proper direction. How do you reverse polarity on an electric motor that only has one wire to it ? [Next page](https://community.cartalk.com/t/positive-or-negative-ground/161072.md?page=2)