CONVERTING FROM POSITIVE TO NEGATIVE GROUND

A lot of people end up converting their old Jag or other British car from positive to negative ground in order to use modern electronics like radios or navigation systems.  The conversion process will not effect most electrical equipment in your Jag, but - of course - you will no longer be able to use the standard equipment positive ground fuel pump(s).  So take care to purchase and install new duel polarity or negative ground pumps before you begin.  I'd suggest sticking with SUs to get the correct fuel pressure.

Now the good news is that the conversion is a simple straight forward proposition.  Here's how:

1.  Make sure your electrical components are turned off.

2.  Unbolt the battery cables from their sources and reinstall them so that the negative terminal now goes to ground.  This may require swapping the battery's position 180 degrees to make the cables reach properly.

3.  Now swap the wires on the coil.  Just switch the two small wires from one side to the other.

4.  Next you have to reverse the residual magnetism in your generator.  Disconnect the wire from the "field" terminal (f) and then momentarily short the (b) terminal to the (f) terminal with a short piece of wire (only touch it briefly).  Do this several times.  You should get a small spark, but don't worry.  Reconnect the wires.

That's it!  You are converted to negative ground.  You can start the car and see if it operates properly. 
 

Copyright 2008