KINGBOLT 7D3162 - Caterpillar

System Operation Description:The ignition transformers initiate combustion by providing high voltage to the spark plugs. The positive output from the secondary circuit of the transformer is at the connection for the terminal of the transformer and the terminal of the spark plug. The transformers are located underneath the valve covers. Each transformer is grounded to a valve cover via a ground spring.The secondary circuit of the transformer provides an initial 8,000 to 37,000 volts to the spark plug. This voltage ionizes the spark plug gap. This voltage is then reduced to about 1000 volts. The total duration of the spark is approximately 400 microseconds.Each Electronic Control Module (ECM) can diagnose the primary circuit of the ignition transformers for open circuits and/or for short circuits. Secondary open circuits and short circuits will not directly shut down the engine. However, these conditions may lead to misfire which can cause lugging of the engine. Lugging of the engine can cause a shutdown.Logged diagnostic codes provide a historical record. Before you begin this procedure, use the Caterpillar Electronic Technician (ET) to print the logged codes to a file.Note: Ignition transformers from Electronic Ignition Systems (EIS) are not interchangeable with the transformers in this engine.Caterpillar spark plugs are high voltage devices with internal resistors. The spark plugs operate at a voltage that is greater than 5,000 volts.Most ignition systems are not affected by resistance in the secondary circuit. If a measurement of the resistance is desired, a megohmmeter must be used. A low voltage multimeter will not provide a reliable reading of the resistance because oxidation of the spark plug's internal components will affect the readings of those meters.Test Step 1. Check the Status Screen of Cat ET for the Output of the Secondary Circuits of the Transformers
Set the engine control to the OFF/RESET mode. Remove the electrical power from the engine.
Connect Cat ET to the service tool connector.
Restore the electrical power to the engine. Set the engine control to the STOP mode.
Set up two status screens for Cat ET. Use eight of the following labels for parameters on each Status screen:
Table 1
Parameters for the Status Screens on Cat ET    
Screen 1
Group 8     Screen 2
Group 9    
"Cylinder #1 Transformer Secondary Output