0393988 JOHNSON MOTOR AND CABLE ASSY.

Table 1
Diagnostic Codes Table
Description Conditions which Generate this Code System Response
401-5 Ignition Transformer Secondary #1 : Current Below Normal
402-5 Ignition Transformer Secondary #2 : Current Below Normal
403-5 Ignition Transformer Secondary #3 : Current Below Normal
404-5 Ignition Transformer Secondary #4 : Current Below Normal
405-5 Ignition Transformer Secondary #5 : Current Below Normal
406-5 Ignition Transformer Secondary #6 : Current Below Normal
407-5 Ignition Transformer Secondary #7 : Current Below Normal
408-5 Ignition Transformer Secondary #8 : Current Below Normal
409-5 Ignition Transformer Secondary #9 : Current Below Normal
410-5 Ignition Transformer Secondary #10 : Current Below Normal
411-5 Ignition Transformer Secondary #11 : Current Below Normal
412-5 Ignition Transformer Secondary #12 : Current Below Normal
413-5 Ignition Transformer Secondary #13 : Current Below Normal
414-5 Ignition Transformer Secondary #14 : Current Below Normal
415-5 Ignition Transformer Secondary #15 : Current Below Normal
416-5 Ignition Transformer Secondary #16 : Current Below Normal While the engine is started, the Electronic Control Module (ECM) detects a low current flow in the secondary circuit for the ignition transformer. The code is logged.
The alarm output is activated.
Table 2
Diagnostic Codes Table
Description Conditions which Generate this Code System Response
401-6 Ignition Transformer Secondary #1 : Current Above Normal
402-6 Ignition Transformer Secondary #2 : Current Above Normal
403-6 Ignition Transformer Secondary #3 : Current Above Normal
404-6 Ignition Transformer Secondary #4 : Current Above Normal
405-6 Ignition Transformer Secondary #5 : Current Above Normal
406-6 Ignition Transformer Secondary #6 : Current Above Normal
407-6 Ignition Transformer Secondary #7 : Current Above Normal
408-6 Ignition Transformer Secondary #8 : Current Above Normal
409-6 Ignition Transformer Secondary #9 : Current Above Normal
410-6 Ignition Transformer Secondary #10 : Current Above Normal
411-6 Ignition Transformer Secondary #11 : Current Above Normal
412-6 Ignition Transformer Secondary #12 : Current Above Normal
413-6 Ignition Transformer Secondary #13 : Current Above Normal
414-6 Ignition Transformer Secondary #14 : Current Above Normal
415-6 Ignition Transformer Secondary #15 : Current Above Normal
416-6 Ignition Transformer Secondary #16 : Current Above Normal While the engine is started, the ECM detects an excessive current flow in the primary circuit for the ignition transformer. The code is logged.
The alarm output is activated. The ignition transformers initiate combustion by providing high voltage to the spark plugs. The output from the secondary circuit of the transformer provides voltage to the terminals 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 V to the spark plug. This voltage ionizes the air that is in the spark plug gap and generates a spark in the air gap. This voltage is then reduced to about 1,000 V. The total duration of the spark is approximately 400 microseconds.The 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.Note: Ignition transformers that are used with Electronic Ignition Systems (EIS) are not interchangeable with the transformers that are used with ADEM III systems. Be sure not to interchange these components on any engine.Caterpillar spark plugs are high voltage devices with internal resistors. The spark plugs operate at a voltage that is greater than 5,000 V.Most ignition systems are 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. Oxidation of the spark plugs internal components will affect the readings for those meters.Test Step 1. Use Caterpillar Electronic Technician (ET) to Check the Output of the Transformers
Set the engine control switch to the OFF/RESET position. 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 switch to the STOP position.
Set up two status screens for Cat ET. Use the following labels for parameters on each Status screen:
Table 3
Parameters for the Status Screens on Cat ET
Screen 1 Screen 2
"Cylinder #1 Transformer Secondary Output Voltage Percentage" "Cylinder #2 Transformer Secondary Output Voltage Percentage"
"Cylinder #3 Transformer Secondary Output Voltage Percentage" "Cylinder #4 Transformer Secondary Output Voltage Percentage"
"Cylinder #5 Transformer Secondary Output Voltage Percentage" "Cylinder #6 Transformer Secondary Output Voltage Percentage"
"Cylinder #7 Transformer Secondary Output Voltage Percentage" "Cylinder #8 Transformer Secondary Output Voltage Percentage"
"Cylinder #9 Transformer Secondary Output Voltage Percentage" "Cylinder #10 Transformer Secondary Output Voltage Percentage"
"Cylinder #11 Transformer Secondary Output Voltage Percentage" "Cylinder #12 Transformer Secondary Output Voltage Percentage"
"Cylinder #13 Transformer Secondary Output Voltage Percentage" "Cylinder #14 Transformer Secondary Output Voltage Percentage"
"Cylinder #15 Transformer Secondary Output Voltage Percentage" "Cylinder #16 Transformer Secondary Output Voltage Percentage"
"Cylinder #17 Transformer Secondary Output Voltage Percentage" "Cylinder #18 Transformer Secondary Output Voltage Percentage"
"Cylinder #19 Transformer Secondary Output Voltage Percentage" "Cylinder #20 Transformer Secondary Output Voltage Percentage"
Start the engine. Allow the engine to warm up to normal operating temperature. Apply the normal load at rated speed.
Observe the value of the output for the secondary circuit of each transformer. Expected Result:The displayed value of the output for the secondary circuit of each transformer is between 1 and 90 percent.Results:
OK - The displayed value of the output for the secondary circuit of each transformer is between 1 and 90 percent.Repair: The ignition system components are operating properly. Investigate other possible root causes of the problem. Troubleshoot the symptom. Refer to Troubleshooting, "Symptom Troubleshooting".STOP
Not OK - At least one of the outputs displayed a value of 0 percent or a value that is greater than 90 percent. The ignition system components require maintenance. Proceed to Test Step 2.Test Step 2. Inspect the Condition of the Transformer
Ignition systems can cause electrical shocks. Avoid contacting the ignition system components and wiring.Do not attempt to remove the valve covers when the engine is operating. The transformers are grounded to the valve covers. Personal injury or death may result and the ignition system will be damaged if the valve covers are removed during