hey are located inside the distributor and function as the trigger for the ignition system to produce spark. The pickup coil monitors the rotation
For flashing headlights just put a new one in.
Coil's are pretty inexpensive, if it is old, you could just buy a new one put install. If you want to test use an ohm meter to see if power is making it into the coil, and then make sure it is flowing form the distributor to the plug. the first way is kinda of technical, the plug test just requires that you put the plug wire against something metal and try to fire the motor.
Take off the modual and coil pack take it to autozone they will test it free.
In short, YES.
Next time you replace the coil, test and if necessary replace the resistor.
If you are not getting spark to any of the plugs could be coil rotor and/or cap HEI ignition?
That year blazer does not have either one of those sensors. If you are not getting any spark to the spark plugs. You should replace ingnition module. Need to make sure the coil wire is good, check ingnition coil also.
There is a test procedure for that using an ohm meter. Consult a Chilton's or similar repair manual.
test ignition coil,ignition module,pick-up coil,electronic spark control,and knock sensor
Have a fuel pressure test done. A 4.3L should have 60 to 66 psi, a 2.2L should have 41 to 47 psi.
Could be a bad fuel pump.
Check the carborator, fuel pump, fuel filter, fuel pickup tank unit. If all are ok then replace the coil and check test light for power with key on for power to hot side coil. If all else fails call your local garage for an appointment to your 305 cheby.