ELBOW 3D8884 - Caterpillar

System Operation Description:The idle/rated switch allows the operator to maintain the engine at low idle. This is allowed after sufficient oil pressure has been obtained. Idle mode is activated by an open circuit at the idle/rated Input to the ECM. Rated mode is selected by connecting the idle/rated input to ground. The idle/rated input should measure approximately 24 VDC at P14-17. The switch input is open at this time. When the switch is closed, the voltage will be less than .5 VDC.Use this procedure to troubleshoot the electrical system if a problem is suspected with the circuit for the idle/rated switch.
Illustration 1 g01627553
Illustration 2 g01635735
(17) Idle/Rated switchTest Step 1. Inspect the Electrical Connectors and the Wiring
Remove electrical power from the ECM.
Thoroughly inspect the P17/J17 connector for the idle/rated switch. Inspect the ECM connector J14/P14. 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 circuit for the coolant level sensor.
Check the allen head screw on the ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.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 are OK. Proceed to Test Step 2.
Not OK - There is a problem with the connectors and/or the wiring.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.Verify that the repair eliminates the problem.STOPTest Step 2. Check the Switch Status with an Electronic Service Tool
Turn the engine control switch to the OFF position.
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Turn the engine control switch to the ON position. The engine should remain in the OFF position.
Observe the status of the idle/rated switch on Cat ET. Operate the idle/rated switch and observe the status.Expected Result:The status of the idle/rated switch should read "Idle" when the switch is open. The status of the idle/rated switch should read "Rated" when the switch is closed.Results:
OK - Repair: The idle/rated switch is functioning properly. Refer to Troubleshooting, "Electrical Connectors - Inspect".STOP
NOT OK - The status of the idle/rated switch does not read "Idle" when the switch is open. The status of the idle/rated switch does not read "Rated" when the switch is closed. Proceed to Test Step 3.Test Step 3. Short the Switch Inputs at the Switch
Turn the engine control switch to the OFF position.
Disconnect the wires from the idle/rated switch.
Turn the engine control switch to the ON position. The engine should remain in the OFF position.
Connect and disconnect the wires for the idle/rated switch. Observe the status on Cat ET.Expected Result:The status of the idle/rated switch