EDGE 2204691 - Caterpillar

Illustration 1 g00775206
Schematic for the Rotary Switch (Variable Shift Control)This diagnostic code is recorded when the status of both the N/O and the N/C switch inputs of the power train ECM are grounded. The switch has three inputs to the power train ECM. During normal operation, two of the inputs are open and the other input is grounded.
Table 1
Status of Variable Shift Control Switch    
Switch Contact    X972-PU Circuit
J1-39    X973-BU Circuit
J1-24    X974-BR Circuit
J1-20    
2     Closed     Open     Open    
3     Open     Closed     Open    
4     Open     Open     Closed    Note: This procedure can cause new diagnostic codes to be recorded. Ignore these created diagnostic codes. Complete the following procedure. Then clear the created diagnostic codes.Note: Ensure that the diagnostic code is active and that the diagnostic code indicator is active.Test Step 1. Check for an Open Circuit.
Observe the ON/OFF status of the diagnostic code indicator.
Disconnect the connector for the switch from the harness.Expected Result:The active diagnostic code changes from "04" to "03".Results:
YES - The active diagnostic code changes from "04" to "03".Repair: The switch has failed. Repeat the previous step in order to verify that the switch has failed. Repair the switch or replace the switch. Stop.
NO - The active diagnostic code does not change from "04" to "03". The switch is not the cause of this diagnostic code. Proceed to test step 2.Test Step 2. Check the Harness Circuit.This test checks the continuity of the entire harness circuit that has failed. The switch that was checked in the previous step is rechecked in this test step.
Turn the key start switch and the disconnect switch to the OFF position.
Connect the switch from Step 1 to the harness.
Disconnect the harness connector J1 from the power train ECM.
Check for continuity to ground. Activate the switch and deactivate the switch when this test step is performed. Refer to table 1 for the correct switch status.Expected Result:The continuity check does not agree with the preceding table.Results:
YES - The continuity check does not agree with the preceding table.Repair: The harness circuit has failed. There is a short to ground in the harness between the power train ECM and the switch. Repair the harness or replace the harness. Stop.
NO - The continuity check agrees with the switch status from the preceding table.Repair: The harness circuit is correct. It is unlikely that the power train ECM has failed. Exit this procedure and perform this test procedure again. If the cause is not found, replace the power train ECM. Refer to Testing and Adjusting, "Electronic Control Module (Power Train) - Replace". Stop.