Ballast resistors are one of three different types, but all are nichrome wire, which is a resistive wire. A porcelain block with two terminals was the most common type on early GM vehicles. The bybass wire connects to the coil side of the resistor, so two wires there. The porcelain block has the nichrome resistor wound in a coil inside the block. I think Ford used a similar type, but it had a metal case, if I remember correctly. Later GM and Ford vehicles used a stranded resistor wire laid in the front-end wire harness. This wire connects directly to the coil primary + terminal; the bypass wire attaches to the same terminal on the coil. This setup was often called the 'loom resistor' or 'harness resistor' or 'internal resistor.' The other type is commonly called 'external.' The 'internal' resistor wire has a high-temperature insulation with a white fiberglass jacket. The wire looks like steel, but the material is nichrome, which is much stiffer than stranded copper of the same size. Another resistor is the two-element unit used by quite a few Chrysler vehicles. I don't remember the purpose of the second side in the Chrysler units, but I think it has to do with the alternator or voltage regulator they used. Bypass circits connect to the coil by way of a connection in the ignition switch, or off a terminal on the starter solenoid. Delco starter solenoids have a terminal marked I, Ign, or R for the bypass- I don't remember all the variables. Ford systems and others that use a Ford starter circuit have a connection on the fender-mounted solenoid/contactor for the ignition resistor bypass. I think those are marked I or Ign for the ignition terminal- you can hot-wire a Ford system quite easlily with that setup. Some Chrysler systems didn't use a bypass system because the ballast resistor was built into the coil primary. Those often caused hard starting in cold weather. Chrysler also used a bypass circuit in the ignition switch, or on a starter relay. Memory is foggy on some of the Chrysler systems.
Harvester
