PLUG 4790462 - Caterpillar

Illustration 1 g00679230
Ignition transformer
An ignition transformer for each cylinder enables the control system for the engine ignition system to use low voltage (108 v). This low voltage is sent to the transformers by the Electronic Control Module (ECM). The transformers increase the voltage to the high voltage (8,000 to 37,000 v) that is needed to fire the spark plugs.In an ignition system that uses high voltage, the loss of current through the secondary wiring can be substantial. Routing of several wires that conduct high voltage increases the chance of an insulation failure which can result in a short circuit to ground. Also, the current in the wiring can be affected in a manner that is like the current in a transformer. An induced voltage can be exchanges between circuits in the harness. This induced voltage can cause a loss of power and misfire. An ignition system that uses low voltage has these advantages over a system that uses high voltage:
Line loss through the secondary wiring is reduced.
The possibility of insulation failure and grounding of the current is reduced.
The possibility of the exchange of an induced voltage is reduced.For proper operation, the low voltage terminals of the transformer must be clean and tight. The ground for the primary ignition coils and secondary ignition coils (negative terminals) have a "−" mark. The positive terminals of the transformers have a "+" mark.