HERES WHAT I HAVE DONE.
DISCONECTED OLD COIL FROM CAR[COIL LEAD,POSITIVE CONNECTION,NEGATIVE CONNECTION ALSO ONE OF THE WIRES HAD A SMALL BOX THAT WAS ATTACHED TO THE COIL BRACKET REMOVED THIS AS IT CONNECTED TO ONE OF THE LEADS WITH A ORIGINAL CONNECTOR.TAPED UP WHAT WAS LEFT 2 LEADS THAT WENT TO POSITIVE AND NEGATIVE ON COIL.THERE IS A SMALL GREEN WIRE WITH AN ORIGINAL BULLET CONNECTOR JOINING THEM TOGETHER THIS LOOKS STANDARD,IF I UNPLUG THIS THEN THE TACH DIES THIS HAS ALWAYS BEEN CONNECTED.PLEASE HELP.CHEERS MARK 0191 5840361