55.2-59 Electrical

[dsraven]

clarify "when I turn the key to kill the ignition, it doesn't turn it off". it stays running like normal and would keep running for days unless you stall it? it idles fast normally but now it stays running after the key is turned off but not running smoothly when this happens, more like running like a diesel or "run on" so it pings and runs rough etc? (this can be because of a fast idle with no idle stop solenoid to close the throttle plates when the key is off. a hot engine can draw enough air/fuel through the partially open throttle to keep the engine running in a "dieseling" style scenario where hot spots in the cylinders act like glow plugs and actually ignite the air fuel mixture). some other explanation?
clarify what you have for engine, ignition system (points or electronic), voltage (12 volts I assume), ignition switch type (old style on the dash or newer style in a swapped steering column), starter actuator type (old "step on the starter pedal", retro fitted push button start on the dash, old style ignition switch with "start" position, newer style ignition switch in a retrofitted steering column from a newer vehicle), alternator or generator etc
ensure there is a good dedicated ground to the frame, cab and engine
test ign switch operation
test for voltage at the distributor/coil with key on engine not running, key on and engine running and then key off when engine wants to stay running
test alternator next (could be back feeding power but usually the battery also dies overnight because the diodes in the alt allow the battery to be drained)
anyway, more info required
what was wrong with the tail lights, could possibly be a ground issue that affects the ignition system also?