ROD AS 1620677 - Caterpillar

Illustration 1 g01197956
Schematic for the Fine Modulation Rocker SwitchThis diagnostic code is recorded when both inputs are either open or both inputs are shorted to the +battery circuit. This switch has two inputs to the ECM. The inputs are normally open and normally closed. During proper operation, one input is open and the other input is grounded.The possible causes for this diagnostic code are listed:
The switch is disconnected.
There is an open circuit in the wire harness.
Short to the +battery circuit in the harness.
The switch has failed.System Response:The machine response is listed:
The implements will not work.Note: Table 1 contains wire numbers and connector contacts. Use this information to troubleshoot the failed circuit.
Table 1
Switch Continuity    
Switch / CID     Switch State     Implement ECM Connector Contact No.     Switch Contact     Wire No.     Status    
CID 1718 Fine Modulation Rocker Switch     OFF     J1-43 N/O (1)     N/O     T869-WH     O (2)    
J1-63 N/C (3) N/C     T870-BR     G (4)    
ON J1-43 N/O     N/O     T869-WH     G    
J1-63 N/C N/C     T870-BR     O    
( 1 ) N/O = Normally Open.
( 2 ) O = Open (no continuity to ground).
( 3 ) N/C = Normally Closed.
( 4 ) G = Grounded (continuity to ground).Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code is corrected.Ensure that the diagnostic code is active. Test Step 1. CHECK FOR OPEN CIRCUIT
Turn the keyswitch to the OFF position.
Turn the disconnect switch to the OFF position.
Verify that the implement lockout switch is connected.
Disconnect the harness from the ECM.
Activate the switch. At the harness connector for the ECM, check the continuity to ground of the normally closed contact and the normally open contact.Expected Result:The continuity check does not agree with Table 1.Results:
YES - The continuity check does not agree with the preceding table. Proceed to test step 2.
NO - The continuity agrees with the values in the preceding table. Proceed to test step 3.Test Step 2. CHECK THE SWITCH
Disconnect the harness from the switch.
At the harness connector for the ECM, check the continuity to ground of the normally closed contact and the normally open contact. Activate the switch when this check is being performed.Expected Result:The continuity check does not agree with the values in Table 1.Results:
YES - The continuity check does not agree with the preceding table.Repair: The switch has failed. Repair the switch or replace the switch. Stop.
NO - The continuity check agrees with the preceding table.Repair: The harness has failed. Repair the harness or replace the harness. Stop.Test Step 3. CHECK FOR A SHORT TO +BATTERY
Check the continuity from each switch wire at the harness connector for the ECM to contacts J1-31.Results:
YES - Continuity exists