0437541 JOHNSON CARBURETOR BODY ASSY., 115

Illustration 1 g00933486
Test Step 1. Check for Connector Damage.
Turn the keyswitch to the OFF position.
Thoroughly inspect the ECM connector J1/P1 and the machine connector J2/P2. Inspect all of the other connectors. Refer to the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.
Check the ECM connector (allen head screw) for the proper torque of 2.25 0.25 N m (20 2 lb in).
Check the customer connector (allen head screw) for the proper torque of 2.25 0.25 N m (20 2 lb in).
Check the harness and the wiring for abrasion and for pinch points.Expected Result:The connectors and wiring are free of the following problems: damage, corrosion, abrasion and incorrect attachment.Results:
OK - The connectors and the wiring are okay. Proceed to Test Step 2.
Not OK - The connectors and/or wiring need repair.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Stop.Test Step 2. Check the Status of the Diagnostic Enable Switch on the Cat ET.
Connect Cat ET to the cab service tool connector J31. Start Cat ET.
Turn the keyswitch to the ON position. The engine should be off.
Operate the diagnostic enable switch. Observe the status for the diagnostic enable switch on Cat ET.Expected Result:The status of the diagnostic enable switch reads "ON" when the diagnostic enable switch is in the ON position. The status of the diagnostic enable switch reads "OFF" when the diagnostic enable switch is in the OFF position.Results:
OK - The status of the diagnostic enable switch reads "ON" with the diagnostic enable switch in the ON position. The status of the diagnostic enable switch reads "OFF" when the diagnostic enable switch is in the OFF position. The diagnostic enable switch is operating normally.Repair: There may be an intermittent problem. If the problem is intermittent, perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors". Stop.
Not OK - The status of the diagnostic enable switch does not read "ON" with the diagnostic enable switch in the ON position. The status of the diagnostic enable switch does not read "OFF" when the diagnostic enable switch is in the OFF position. The diagnostic enable switch is not operating normally. Proceed to Test Step 3.Test Step 3. Short the Wires together at the Diagnostic Enable Switch.
Turn the keyswitch to the OFF position.
Record the position of the wiring on the diagnostic enable switch before removing the wires.
Disconnect the wires from the diagnostic enable switch.
Create a short circuit at the diagnostic enable switch between the wire C915-GY and the digital return wire 998-BR.
Turn the keyswitch to the ON position. The engine should be off.
Observe the status of the diagnostic enable switch on Cat ET.
Turn the keyswitch to the OFF position.
Remove the short between the wire C915-GY and the digital return wire 998-BR.
Turn the keyswitch to the ON position. The engine should be off.
Observe the status of the diagnostic enable switch on Cat ET.
Turn the keyswitch to the OFF position.
Remove the wire short.Expected Result:The status of the diagnostic enable switch reads "ON" when the wire C915-GY and the digital return wire 998-BR are shorted together. The status for the diagnostic enable switch reads "OFF" when the wire C915-GY and the digital return wire 998-BR are not shorted together.Results:
OK - The status of the diagnostic enable switch reads "ON" when the wire C915-GY and the digital return wire 998-BR are shorted together. The status of the diagnostic enable switch reads "OFF" when the wire C915-GY and the digital return wire 998-BR are not shorted together. The problem is not with the harness and/or with the ECM.Repair: Temporarily connect a new diagnostic enable switch. Verify that the new diagnostic enable switch solves the problem before you permanently install the new diagnostic enable switch. Stop.
Not OK - The status of the diagnostic enable switch does not read "OFF" when the wire C915-GY and the wire 998-BR are shorted together. The status of the diagnostic enable switch does not read "ON" when the wire C915-GY and the wire 998-BR are shorted together. There is a problem in the harness and/or with the ECM. Proceed to Test Step 4.Test Step 4. Check for a Short Circuit in the Wiring Harness.
Turn the keyswitch to the OFF position.
Disconnect the ECM connector J1/P1 and disconnect the wires at the diagnostic enable switch.
Measure the resistance between the wire C915-GY at ECM connector P1-52 and the digital return wire 998-BR at ECM connector P1-9.
Measure the resistance between the wire C915-GY at the ECM connector P1-52 and the engine ground.
Measure the resistance between the wire 998-BR at the ECM connector P1-9 and the engine ground.Expected Result:The resistance is greater than 20,000 Ohms for each measurement.Results:
OK - The resistance is greater than 20,000 Ohms for each measurement. Proceed to Test Step 5.
Not OK - The resistance is less than 20,000 Ohms for one or more of the measurements. There is a short circuit in the harness between the diagnostic enable switch and the ECM.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Stop.Test Step 5. Check for an Open Circuit in the Harness.
Create a short circuit at the diagnostic enable switch between the wire C915-GY and the digital return wire 998-BR.
Measure the resistance between the wire C915-GY at the ECM connector P1-52 and the digital return wire 998-BR at the ECM connector P1-9.
Remove the wire short.Expected Result:The resistance is less than 5 Ohms.Results:
OK - The resistance is less