CRANKSHAFT AS 9Y7605 - Caterpillar

System Operation Description:Note: The idle/rated switch only applies to engines that are equipped with the air/fuel ratio control.The air/fuel ratio control has an input for the desired speed. The Electronic Control Module (ECM) uses the desired speed input only when the idle/rated switch is in the "RATED" position.There are no diagnostics for the idle/rated switch. Perform this procedure if the engine does not respond to a change in the position of the switch.When the switch is in the "IDLE" position, the circuit is open. When the switch is in the "RATED" position, a ground is supplied to the J1-36 input of the ECM.
Illustration 1 g01045566
Schematic diagram of the idle/rated switchThe engine is equipped with a remote control panel that includes a status control module and air/fuel ratio control. The idle/rated switch is shown in the "IDLE" position.
Illustration 2 g01045567
Schematic diagram of the idle/rated switchThe engine is configured for Canadian Standards Association (CSA). The engine is equipped with an optional remote control panel with air/fuel ratio control. The idle/rated switch is shown in the "IDLE" position.Test Step 1. Inspect the Electrical Connectors and the Wiring
Set the engine control to the OFF/RESET mode. Remove the electrical power from the engine.Note: For the following steps, refer to Troubleshooting, "Inspecting Electrical Connectors".
Thoroughly inspect each of the following connectors:
J1/P1 connectors on the ECM
Connections for the idle/rated switch
Illustration 3 g01045829
Harness side of the P1 connector (P1-3) Ground for the sensors (P1-36) Input for idle/rated switch
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit for the idle/rated switch.
Check the terminal strips for corrosion and for mechanical failure.
If the engine is equipped for CSA, check the harnesses and the wiring for abrasion and for pinch points between the idle/rated switch and the ECM.Expected Result:The connectors, pins, and sockets are connected properly. The terminal strips do not have corrosion or mechanical failure. The connectors and the wiring do not have corrosion, abrasion, or pinch points.Results:
OK - The components are in good condition with proper connections. Proceed to Test Step 2.
Not OK - The components are not in good condition and/or at least one connection is improper.Repair: Perform the necessary repairs and/or replace parts, if necessary.STOPTest Step 2. Check the Wiring for an Open Circuit
Remove the electrical power from the engine.
Disconnect the P1/J1 connectors.
Use a multimeter to check for an open circuit between the points that are listed in Table 1. During each measurement, wiggle the wires in the harness in order to check for an intermittent problem. Be sure to wiggle the wires near each of the connectors.
Table 1
Resistance Measurements for the Wiring for the Idle/Rated Switch    
Connector and Terminal    Terminal on the Idle/Rated Switch    
P1-3 (Ground for the sensors)     The terminal that is connected to the C271-BK wire or the C270-BK wire    
P1-36 (Input for the idle/rated switch)     The terminal that is connected to the C273-WH wire    Expected Result:Each check of