BLOCK 4M8155 - Caterpillar

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Test Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
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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 Troubleshooting, "Electrical Connectors - Inspect" for details.
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P1 ECM connector (P1-22) Throttle switch (N/O) (P1-23) Throttle switch (N/C)
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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 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.
Turn the keyswitch to the ON position.
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 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
Turn the keyswitch to the OFF position.
Use Cat ET to check the condition of the circuit between the throttle switch and the relay:
Disconnect the connector