ELBOW 7N6253 - Caterpillar

Use this procedure to determine if the circuit for the ignore brake/clutch switch is operating correctly. There are no diagnostic codes for this circuit.Background InformationSome vehicle applications require mobile use of the vehicle during PTO operation. When the ignore brake/clutch switch is ON, depressing the brake or the clutch will not disengage PTO operation or a set engine speed. If the "Ignore Brake/Clutch Switch" parameter is programmed to "None" (default), this feature is not used. If the "Ignore Brake/Clutch Switch" parameter is programmed to "J1/P1:47", then the feature is available and the switch circuit must be connected to terminal P1-47.
Illustration 1 g00955558
Typical schematic for the ignore brake/clutch switch
Note: The circuit's return may be connected to terminal P1-3, P1-5, or P1-18.
Illustration 2 g01151227
Pin locations on ECM connector
(P1-18) Input sensor common 1
(P1-47) Input 5 (Ignore brake/clutch switch) 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 any wires in the ECM connector that are associated with the circuit for the ignore brake/clutch 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 for pinch points from the ignore brake/clutch switch to the ECM. Refer to Illustration 2 for terminal locations for 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.
No - The wiring is not OKRepair: .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 Ignore Brake/Clutch Switch
Connect Caterpillar Electronic Technician (ET) to the data link connector.
Turn the ignition key switch to the ON position.
Operate the switch in the ON and OFF positions.
View the status for parameter "Ignore Brake/Clutch Switch" on Cat ET.
If the status for parameter "Ignore Brake/Clutch Switch" indicates "None", then the "Ignore Brake/Clutch Switch" parameter has not been programmed. Expected Result:The status screen indicates "On" when the switch is turned on. The status screen indicates "Off" when the switch is turned off.Results:
Yes - The switch is operating normally. Continue troubleshooting if the original condition is not resolved.STOP
No - The ECM is not reading the change in switch status. Proceed to Test Step 3.Test Step 3. Check the Switch Circuit at the ECM
Illustration 3 g01151232
Pin locations on breakout T
(18) Input sensor common 1
(47) Input 5 (Ignore brake/clutch switch)
Turn the ignition key switch to the OFF/RESET position.
Install a breakout T to the ECM vehicle harness connector J1/P1.
Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.
Insert the jumper wire into terminal 18 (Input Sensor Common 1) of the breakout T. Insert