F1425 Force HEX CAP SCREW, 1/4 - 20 X 2 5/8

Illustration 1 g01241286
Schematic of the circuit for the speed control
Test Step 1. Inspect the Electrical Connectors and the Wiring
Remove the electrical power from the ECM.
Illustration 2 g01186024
Location of the J1/P1 ECM connectors (typical left side engine view)
Thoroughly inspect the J1/P1 ECM connector. Inspect all of the connectors that are associated with the circuit. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 3 g01241291
Terminal locations on the P1 ECM connector for the speed control
(P1-66) Primary throttle
(P1-68) Secondary throttle
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors and the connector for the EMCP that are associated with the circuit.
Check the torque of the allen head screws for each of the ECM connectors. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and the wiring for abrasion and for pinch points from the batteries to the ECM. Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - The connectors and wiring appear to be OK. Proceed to Test Step 2.
Not OK - The connectors and/or wiring are not OK.Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. Verify that the original problem has been resolved.STOPTest Step 2. Check for Active Diagnostic Codes
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Restore the electrical power to the ECM.
Monitor the active diagnostic code screen on Cat ET. Check for an active 08 code. Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
Remove the electrical power from the ECM. Expected Result:No diagnostic codes are active.Results:
OK - No diagnostic codes are active.Repair: If the above code has been logged, there may be an intermittent problem in the harness or in a connector. Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect" in order to troubleshoot intermittent electrical problems.If a problem with the speed control circuit is suspected, proceed to Test Step 3.
Not OK - A 08 diagnostic code is active at this time. The ECM has detected an erratic signal at the input for the throttle signal. Proceed to Test Step 3.Test Step 3. Check the Supply Voltage to the Speed Control
Restore the electrical power to the ECM.
Start the engine.
Measure the voltage between terminals +B and −B at the speed control.
Stop the engine. Remove the electrical power from the ECM. Expected Result:The supply voltage is 24 3.0 VDC at the speed control.Results:
OK - The engine started and the supply voltage is 24 3.0 VDC at the speed control. The speed control is receiving supply voltage. Proceed to Test Step 4.
Not OK - The supply voltage is not 24 3.0 VDC.Repair: The supply voltage is not reaching the speed control.If the engine started, the control relay is receiving electrical power. There is a problem in the harness or the connectors between the output of control relay and the speed control. The problem may be in the ground circuit to the speed control. Perform the following Test Steps:
Ensure that the battery isolator switch is in the ON position.
Remove the wire from the −Battery terminal at the speed control.
Check the resistance between the wire for the −Battery at the speed control and the battery negative post. The correct measurement will indicate that a short circuit condition exists for the circuit.If the resistance measurement indicates a short circuit, the ground circuit for the speed control is OK. There is a problem in the harness or the connectors between the control relay and the speed control. Repair the harness and/or the connectors. Replace parts, if necessary. Verify that the original problem has been resolved.If the measurement did not indicate a short circuit, the problem is in the ground circuit for the speed control. Repair the harness and/or the connectors. Replace parts, if necessary. Verify that the original problem has been resolved.If the engine does not start, there is a problem in the electrical power supply circuit. Refer to the diagnostic functional test Troubleshooting, "Electrical Power Supply Circuit - Test".STOPTest Step 4. Check the Throttle Signals at the Speed Control
Disconnect the wire from terminal S (primary throttle) at the speed control.
Restore the electrical power to the ECM.
Measure the duty cycle of the PWM signal between terminal S and terminal -B at the speed control. Use the speed control's potentiometer to vary the speed of the engine during the measurement. The correct duty cycle will remain between 5 percent and 95 percent during the test. The duty cycle will change with the change in the desired engine speed.
Remove the electrical power from the ECM.
Restore the wiring to the original configuration. Expected Result:The duty cycle measurements agree with the specifications that are stated above.Results:
OK - The duty cycle measurements agree with the specifications. The speed control is operating correctly. Proceed to Test Step 5.
Not OK - The duty cycle measurements do not agree with the specifications.Repair: The speed control is not operating correctly. Replace the speed control. Verify that the original problem has been resolved.STOPTest Step 5. Check the Throttle Signals at the ECM
Disconnect the J1/P1 ECM co