How to convert your Metropolitan from Positive to Negative Ground
The So Cal Mets caution you when you do this change.
DO AT YOUR OWN RISK!
Many Metropolitan owners have converted their cars from the factory original POSITIVE ground to the more standard NEGATIVE ground electrical system. With this conversion, you may add an FM converter, plug items such as Cell Phones, CB radios, and accessories into the cigarette lighter without ruining your electronics. Others have added cd players under dash stereos to their Mets.
AGAIN: DO SO AT YOUR OWN RISK
This tech tip was originally published in the Metropolitan Owners Club of North America’s newsletter The Met Gazette
- Ensure all electrical devices are turned off.
- Ignition switch
- Headlights
- Radio
- Any other device
- Disconnect the battery
- The battery is located under the rear seat. Remove both cables from the battery and clean the battery posts and the cables.
- Swap the two wires going to the spark coil
- Leave the tower wire connecting to the distributor cap
- Connect the wire going to the distributor to the coil terminal marked “SW” or “-“
- Connect the wire going to the wiring harness to the terminal marked “CB” or “+”
- Reconnect the battery
- You will likely have to lift the battery out of its box and rotate it 180 degrees to allow connection to the proper terminals
- Connect the grounding cable (the cable attached to the ground bolt) to the negative post on the battery
- Connect the remaining cable to the positive battery post.
- Re-polarize the generator
- Use a length of jumper wire of at least 16 AWG, stripped on both ends. The wire should be long enough to run from the starter switch to the regulator.
- Have someone hold one end of the wire on the hot side of the starter switch (the side connected to the battery cable).
- BRIEFLY brush the other end of the wire on the “F” terminal on the regulator. You should see a few sparks. Do not make that connection for more than one second.
- Repeat the previous step one time.
- The generator is now polarized to negative ground.
You are now converted. Check all your fuses to see if any blew out, and if you had gauges, you will need to reverse the wires or the display will be backwards. The stock fuel gauge will work correctly.
If your car has an original radio with the mechanical vibrator (you can hear a hum or buzzing sound when you first turn on the radio) you don’t need to do anything
If your radio has had the vibrator replaced with a solid state unit, a new, negative ground vibrator will be needed.
You can now connect an FM converter, radio, and plug stuff into the cigarette lighter without ruining your electronics.
The stock cigarette lighter had a larger diameter than current lighter sockets. You may want to replace it with a new unit to allow plugging in accessories..
References