SPRING 1772510 - Caterpillar

System Operation Description:The intermediate speed switch is a normally open switch. When this switch is closed, the engine speed will decrease to the customer programmable intermediate idle speed. This intermediate speed is the speed rate of the PTO. This will happen regardless of PTO set speed or the desired speed for the throttle position sensor. When the intermediate speed switch is opened, the engine speed will be increased back to the desired engine speed for the throttle or the desired engine speed for PTO operation according to the ramp rate for the PTO speed. If the intermediate idle speed is programmed above the current desired engine speed for the throttle or the desired engine speed for PTO operation, this switch will have no effect on engine speed.
Illustration 1 g01266225
Typical schematic
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P1 connector for the Electronic Control Module (ECM) (P1-5) Digital return (P1-27) Input for the intermediate speed switch
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Location of ECM connectors
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Machine interface connector (Terminal 09) Digital return (Terminal 28) Input for the intermediate speed switchTest Step 1. Inspect Electrical Connectors and Wiring
Turn the switch that provides power to the keyswitch input for the ECM to the OFF position.
Turn the breaker for the ECM to the OFF position.
Thoroughly inspect the ECM connectors J1/P1. Inspect all of the other connectors in the circuit. Refer to Troubleshooting, "Inspecting Electrical Connectors" for the proper procedure for inspecting system wiring.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.
Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.
Check the harness and the wiring for abrasion and for pinch points.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 are 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 Intermediate Speed Switch on Caterpillar Electronic Technician (ET)
Connect Cat ET to the service tool connector.
Turn the breaker for the ECM to the ON position.
Turn the switch that provides power to the keyswitch input for the ECM to the ON position.
Operate the intermediate speed switch. Observe the status for the intermediate speed switch on Cat ET.Expected Result:The status of the intermediate speed switch reads "ON" with the intermediate speed switch in the ON position. The status of the intermediate speed reads "OFF" when the intermediate speed switch is in the OFF position.Results:
OK - The circuit for the intermediate speed switch is operating normally.Repair: If an intermittent condition is suspected, refer to Troubleshooting, "Inspecting Electrical Connectors".STOP
Not OK - The circuit for the intermediate speed switch is not operating normally. Proceed to Test Step 3.Test