No, steel-core wires, or any metal-core wires, are not the problem with this timing light, unless the wire used for the trigger is broken ahead of the trigger connection. A carbon track or crack in the distributor cap might shunt the spark voltage away from that particular wire, causing the light flash to be irregular, but that condition would most likely cause an identifiable misfire. Given that the light flashes somewhat regularly when the associated spark plug wire is disconnected and the spark allowed to jump a small distance, the carbon track/crack possibility seems unlikely. With that, I'm leaning toward the pick-up probe being at fault, or the power supply in the light is at fault. The power supply in the light has to generate something around 300 volts DC in order to trigger the flash tube in the light. The power supply may work adequately with 12 volts in, but not with six volts. The pick-up probe probably is replacable, depending on who made the light. I believe someone mentioned that the probe is a clamp-on type. Clamp-on probes often use a ferrite core which may break if the clamp is dropped, then the operation is erratic. An electronics technician familiar with strobe lights could check the power supply to see if it is working, and maybe repair it, but it might be cheaper to buy a new light. After you have eliminated all the other possibilities. One place to look for a repair shop would be a shop that repairs camera flash equipment. An automotive timing light is nothing more than a camera flash unit with a focusing lens rather than a diffusing lens. And a power supply to work on either 6 or 12 volts input.
Harvester
