The 1999 Jeep Cherokee ignition coil used a black wire for the negative wire. The negative wire should be on the left post.
you have to tap into the coil wires the negative wire on the coil plug.
red (+) wire to possitive side of coil- Black (-) wire to negative side of coil. thats it.
assuming it is a older car with points the distributor goes to the negative side of the coil
Hook it to the negative side of the coil.
The green wire from the tach goes to the negative side of the coil.
If your car has a distributor it is the negative on the coil.
The dark green/orange wire is the power feed.
follow the instructions, if you have no instructions then ussualy one wire to negative side of coil and the other wire goes to ground.
negative side of the coil