Symptoms of a bad ballast resistor may be a crank but no start or start followed by an immediate stall. You will most likely not get any warning of its failure; it may be working fine today and give out tomorrow.What does a ballast resistor do?
“Ballast” is something that gives stability and hence a resistor used for over current or over voltage protection in circuit that in turn gives stability to the circuit is referred to as ballast resistor. These ballast resistors have major applications in areas of automotive and in lamp circuits.Do I need a ballast resistor?
If you have the stock ignition system, you need a ballast resistor. Some coils have an internal ballast, so if you really want to get rid of the external ballast resistor you can get one of those. Keep in mind you'll still have a ballast resistor, it just will be inside the coil instead of out on the firewall.