CAGE 1P1941 - Caterpillar

Use this procedure to determine if the circuit for the torque limit switch is operating correctly. The ECM does not monitor the condition of this circuit.Background InformationThe torque limit switch provides a way to temporarily protect equipment from damage that is caused by applying too much torque. Torque limiting is typically used during PTO operation. However, torque limiting may be activated anytime.In order to use torque limiting, a torque limit must be programmed into the "Torque Limit" parameter. The "Torque Limit" parameter is located under the "Dedicated PTO Parameters". The default setting is 2712 N m (2000 lb ft).The "Torque Limit Switch" parameter must also be programmed. If the "Torque Limit Switch" parameter is programmed to "None" (default), this feature is disabled. If the "Torque Limit Switch" is programmed to J1/P1:7 or to J1/P1:23, the feature is available and the switch circuit must be connected to the corresponding terminal on the P1 connector.
Illustration 1 g00932484
Circuit schematic for torque limit switch
The return may be connected to P1-3, to P1-5, or to P1-18.
Illustration 2 g01152506
Pin locations on ECM connector
(P1-5) AP sensor/switch sensor common
(P1-7) Input 4
(P1-23) Input 19 Test Step 1. Inspect Electrical Connectors and Wiring
Thoroughly inspect the ECM vehicle harness connector J1/P1, the connectors, and the firewall bulkhead connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the torque limit switch.
Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Check the harness and the wiring for abrasion and pinch points from the battery to the ECM. Then, check the wiring from the ignition key switch 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:
Yes - The wiring is OK. Proceed to Test Step 2.
Not OK - The wiring is not OK.Repair: Repair the wiring and connectors or replace the wiring or the connectors. Ensure that all of the seals are properly connected. Verify that the repair eliminates the problem.STOPTest Step 2. Check the Status of the Torque Limit Switch on Caterpillar Electronic Technician (ET)
Establish communication between Cat ET and the ECM. Note: If the "Torque Limit Switch" status indicates "Not Installed", then the "Torque Limit Switch" parameter has not been programmed.
View the "Torque Limit Switch" status on Cat ET.
Set the torque limit switch to the ON position and to the OFF position. Expected Result:The status screen indicates "ON" when the switch is turned on. The status screen indicates "OFF" when the switch is off.Results:
OK - The indications are correct. The switch is operating normally. Continue troubleshooting if the original condition is not resolved.STOP
Not OK - An indication is not correct. The ECM is not reading the input from the switch. Proceed to Test Step 3.Test Step 3. Check the Switch Circuit for the ECM
Illustration 3 g01152509
Pin locations on the breakout T
(5) AP sensor/switch sensor common
(7) Input