KIT-SEAL 1855574 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the following diagnostic codes:
401-5 through 416-5 Ignition Transformer Secondary #1 current below normal through Ignition Transformer Secondary #16 current below normal
401-6 through 416-6 Ignition Transformer Secondary #1 current above normal through Ignition Transformer Secondary #16 current above normalThe 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.The 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.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 Caterpillar Electronic Technician (ET) for the Output of the Secondary Circuits of the Transformers
Establish communication between Cat ET and the ECM. Refer to Troubleshooting, "Electronic Service Tools", if necessary.Note: The "% Secondary Voltage" display is provided as an indicator of the spark plugs' condition. With new spark plugs, the "% Secondary Voltage" value will be low. As the spark plug is used and the wear on the gap increases, the "% Secondary Voltage" value will increase. The increase of the wear on the gap may cause the cylinder to misfire, even though the "% Secondary Voltage" has not reached 100 percent.
Set up a status screen on Cat ET in order to monitor the "Transformer Secondary Output Voltage Percentage" for all of the cylinders. Two status screens are required on 12 cylinder engines and 16 cylinder engines in order to monitor all of the cylinders.
Start the engine. Apply the normal load at rated speed. Allow the engine to warm up to normal operating temperature.
Observe the value of the