0511828 JOHNSON TERMINAL

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 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 0 and 90 percent. The exhaust temperatures for each cylinder are approximately equal to the engine's average exhaust port temperature.Results:
OK - The displayed value of the output for the secondary circuit of each transformer is between 0 and 90 percent. The exhaust port temperatures are OK. The ignition system components are operating properly.Repair: Investigate other possible root causes of the problem. Troubleshoot the symptom. Refer to Troubleshooting, "Troubleshooting Without A Diagnostic Code".STOP
Not OK - There is a diagnostic code for the secondary ignition for a cylinder. That cylinder's exhaust port temperature is at least 20 °C (68 °F) below the average temperature of the engine's exhaust ports. The ignition system components require maintenance. Proceed to Test Step 2.Test Step 2. Inspect 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 engine operation. The engine will not operate without the valve covers.
Set the engine control to the OFF/RESET position.
Illustration 1 g01091169
Section view of the side of a cylinder head
(1) Valve cover
(2) 2-pin connector
(3) Transformer
Remove valve cover (1) of the suspect cylinder.
Pulling on the wiring harness may break the wires. Do not pull on the wiring harness.
Disconnect 2-pin connector (2). Remove transformer (3) from the engine.
Illustration 2 g01256751
Ignition transformer and extension
(3) Transformer
(4) Screws for the ground spring
(5) Ground spring
(6) Spacer
(7) Seal
(8) Secondary terminal for the spark plug
(9) Extension
(10) O-ring seal
Inspect the body of transformer (3) and ground spring (5). Verify that there is no corrosion nor damage. Verify that the screws for ground spring (4) are secure.
Inspect seal 7 for cracks.
Inspect secondary terminal (8) for corrosion and/or for damage.
Inspect O-ring seal (10) inside extension (9) for damage.
Check for a secure connection between the transformer and the spark plug. Note: Pin holes are caused by misfire in the engine that does not generate a diagnostic code.
Check extension (9) near spacer (6) for signs of pin holes and/or of arcing.
The extension can be scratched and damaged with a wire brush. Do not use a wire brush on the extension.
Clean any deposits from the inside of the extension. Use a 6V-7093 Brush with isopropyl alcohol. Expected Result:The transformer is in good condition.Results:
OK - The transformer is in good condition. Proceed to Test Step 3.
Not OK - An inspection found a problem with the transformer.Repair: Repair the transformer, when possible. Replace the transformer, if necessary. Be sure to use the correct transformer for the G3500 (A3) Engine.Reset the control system. Restart the engine. Clear the logged codes.STOPTest Step 3. Check the Primary Circuit and the Secondary CircuitCheck the primary circuit and check the secondary circuit according to Systems Operation/Testing and Adjusting, RENR9352, "Ignition Transformer".Expected Result:The ignition transformer is within the specifications that are outlined in Systems Operation/Testing and Adjusting, RENR9352, "Ignition Transformer".Results:
OK - All of the measurements are correct. Proceed to Test Step 4.
Not OK - At least one of the measurements is incorrect.Repair: Place the engine control switch in the OFF/RESET position. Replace the ignition transformer. Be sure to use the correct transformer for the G3500 (A3) Engine.STOPTest Step 4. Check the Spark Plug
Perform the following procedures according to the instructions in the engine's Operation and Maintenance Manual.
Remove the spark plug from the cylinder head.
Inspect the spark plug.
Clean the spark plug.
Measure the spark plug's resistance after the spark plug has been cleaned. Note: A standard Ohmmeter cannot be used for measuring the resistance of a used spark plug.
Use the 142-5055 Insulation Testing Gp (ELECTRICAL) to measure the resistance of the spark plug. Follow the warnings and instructions that are provided with the tool.
Connect the red lead of the tester to the terminal post. Because the ground strap is close to the center elect