0302979 JOHNSON CHOKE VALVE

Illustration 1 g01273905
SchematicTest Step 1. Inspect the Electrical Connectors and the Wiring
Remove the electrical power from the ECM.
Illustration 2 g01144470
Schematic for throttle switch
Thoroughly inspect the J1/P1 ECM connector. Also, thoroughly inspect all of the connectors that are between the ECM and the throttle switch. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 3 g01273919
P1 ECM connector (P1-44) Throttle switch (N/O) (P1-45) Throttle switch (N/C)
Illustration 4 g01149844
Terminal locations of the relay for the throttle switch
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector and the machine connectors that are associated with the active diagnostic code.
Check the allen head screw for each of the ECM connectors for the proper torque. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" for the correct torque value.
Check the harness and wiring for corrosion, for abrasion, and for pinch points from the throttle switch to the ECM.Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion, and of pinch points.Results:
OK - The harness and wiring appear to be OK. Proceed to Test Step 2.
Not OK - There is a problem in the connectors and/or wiring.Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem.STOPTest Step 2. Check the Status of the Throttle Inputs
Connect the Caterpillar Electronic Technician (ET) to the service tool connector.
Restore the electrical power to the ECM.
Observe the status of the throttle inputs on Cat ET while you operate the throttle switch in each position.Expected Result:The status of the throttle switch corresponds with the position of the switch.Results:
OK - The throttle switch is functioning properly at this time.Repair: Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent.STOP
Not OK - One or more of the inputs is incorrect. Proceed to Test Step 3.Test Step 3. Check the Circuit between the Engine ECM and the Relay
Remove the electrical power from the ECM.
Use Cat ET to check the condition of the circuit between the throttle switch and the relay:
Disconnect the connector from the relay for the throttle switch.
Use a jumper wire to connect relay terminal 30 to relay terminal 87A at the relay connector for the throttle switch. Do not connect the connector to the relay.
Restore the electrical power to the ECM.
Check the status of the throttle switch on Cat ET.The correct status of the throttle switch is low idle.
Remove the jumper wire from relay terminal 87A. Install the jumper wire between relay terminal 87 and relay terminal 30.
Monitor the status of the throttle switch on Cat ET.The correct status of the throttle switch is high idle.
Remove the electrical power from the ECM.
Remove the jumper wire. Reconnect all wires to the original configuration.Expected Result:The correct status of the throttle switch is displayed on Cat ET.Results:
OK - The ECM and the harness to the relay are OK.Repair: The problem is in the circuit from the relay to the throttle switch. The problem may be in the relay. Troubleshoot the remainder of the circuit for the throttle switch. Refer to the correct Schematic for your machine.STOP
Not OK - Cat ET does not display the correct status for the throttle switch. The problem may be the harness to the relay or the ECM. Verify that the wire to chassis ground is not open and that the wire has a good connection to chassis ground. Proceed to Test Step 4.Test Step 4. Check the Operation of the ECM
Remove the wires for the throttle inputs from the P1 ECM connector.
Install a 208-0059 Adapter Cable As (70-Pin Breakout) at the J1 ECM connector. Install the P1 ECM connector.
Use Cat ET to check the status of the throttle switch:
Use a jumper wire to connect terminal 45 to terminal 61 at the breakout harness.
Restore the electrical power to the ECM.
Check the status of the throttle switch on Cat ET.The correct status of the throttle switch is low idle.
Remove the jumper wire from terminal 45. Install the jumper wire between terminal 44 and terminal 61 at the breakout harness.
Monitor the status of the throttle switch on Cat ET.The correct status of the throttle switch is high idle.
Remove the electrical power from the ECM.
Remove the jumper wire and breakout T. Reconnect all wires and connectors to the original configuration.Expected Result:The correct status of the throttle switch is displayed on Cat ET.Results:
OK - The ECM is operating properly.Repair: The problem is in the harness from the ECM to the relay for the throttle switch. Repair the connectors or the harness. If necessary, replace the connectors or the harness.Verify that the repair eliminates the problem.STOP
Not OK - The ECM is not responding to the switch inputs.Repair: Verify your results. Refer to electronic Troubleshooting, "Replacing the ECM" before you replace the ECM.STOP