55910 Force NUT, Special (7/16-20)

Illustration 1 g01176422
Schematic for the backup throttle switch
Test Step 1. Inspect the Electrical Connectors and the Wiring
Turn the keyswitch to the OFF position.
Illustration 2 g01144470
Left side engine view (typical example)
(1) J1/P1 ECM connectors
Illustration 3 g01176423
Operator's control console (typical example)
(2) Backup throttle switch
Thoroughly inspect connectors (1) and (2). Also, thoroughly inspect all of the connectors that are between the ECM and the backup throttle switch. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Illustration 4 g01236003
P1 ECM connector
(P1-5) Return
(P1-41) Backup throttle switch
Illustration 5 g01176431
J705 Backup throttle switch connector
(J705-2) Backup throttle switch
(J705-3) Return
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 Switch Status
Connect the Caterpillar Electronic Technician (ET) to the service tool connector.
Turn the keyswitch to the ON position.
Observe the status of "Throttle Backup" on Cat ET.
Toggle the backup throttle switch and observe the status of the switch.
Turn the keyswitch to the OFF position. Expected Result:The switch status in Cat ET shows that the switch is operating normally.Results:
OK - Cat ET shows the correct switch status.Repair: The switch is operating normally. There may be an intermittent problem in the harness or in a connector.Refer to Troubleshooting, "Electrical Connectors - Inspect" if the problem is intermittent.STOP
Not OK - Cat ET does not show the correct switch status. Proceed to Test Step 3.Test Step 3. Short the Wires at the Connector for the Switch
Turn the keyswitch to the ON position.
Disconnect the J705/P705 backup throttle switch connector at the switch.
Fabricate a jumper wire that is long enough to jumper the terminals at the switch's connector. Crimp spade terminals to each end of the jumper wire.
Observe the status of "Throttle Backup" on Cat ET.
Connect the jumper wire across terminals P705-2 and P705-3 on the harness side of the connector.
Observe the status of "Throttle Backup" on Cat ET while the jumper wire is in place.
Turn the keyswitch to the OFF position. Expected Result:The status of the switch is "OFF" before you install the jumper wire. The status changes to "ON" after you install the jumper wire at the switch's connector.Results:
OK - The switch status in Cat ET changes accordingly.Repair: There is a problem with the throttle backup switch. Replace the throttle backup switch. Verify that the repair eliminates the problem.STOP
Not OK - The switch status in Cat ET does not change according to the test procedure. Connect the J705/P705 connector. Proceed to Test Step 4.Test Step 4. Short the Switch Input at the ECM
Disconnect the J1/P1 ECM connectors. Remove terminal P1-41 from the ECM connector.
Fabricate a jumper wire that can be used to connect between the ECM connector and the engine ground stud. Crimp a socket terminal to one end of the jumper wire.
Install the socket terminal of the jumper wire into terminal location P1-41. Connect the J1/P1 ECM connector.
Turn the keyswitch to the ON position and observe the status of "Throttle Backup" on Cat ET.
Ground the jumper wire to the engine ground stud. Remove the wire from the ground stud.
Turn the keyswitch to the OFF position. Expected Result:The status is "OFF" before you ground the jumper wire. The status changes to "ON" after you install the jumper wire at the engine ground stud.Results:
OK - The ECM properly reads the switch inputs at the ECM connector P1 but not at the switch's connector.Repair: There is a problem with a connector or with the harness. Repair the wiring harness or the connector. Verify that the repair eliminates the problem.STOP
Not OK - The ECM is not reading the switch inputs properly.Repair: Verify your results. If the problem is confirmed, replace the ECM. Refer to Troubleshooting, "Replacing the ECM" for complete instructions.STOP