FUEL SYSTEM 9X2105 - Caterpillar

Illustration 1 g00775206
Schematic for the Rotary Switch (Variable Shift Control)This diagnostic code is recorded when the power train ECM records a short to the +battery. The switch for the variable shift control has three inputs to the power train electronic control module (ECM). During normal operation, two of the inputs are open and the other input is grounded. Use table B in order to determine the connectors and the contacts that correspond to the faulty circuit.
Table 1
Status of the 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.
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the harness connector J1 from the power train ECM.
At the harness connector for the power train ECM, check the continuity to ground of the switch contacts. Refer to table B for the correct switch contacts.Expected Result:The continuity check does not agree with table B.Results:
YES - The continuity check does not agree with the preceding table.Repair: The harness or the switch has failed. Proceed to test step 2.
NO - The continuity agrees with the preceding table. Proceed to test step 3.Test Step 2. Check the Switch.
Disconnect the harness from the switch.
Check the continuity to ground of the switch contacts. Activate the switch and deactivate the switch when this check is performed. Refer to table 1 for the correct status.Expected Result:The continuity check does NOT agree with table B.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 agrees with the preceding table.Repair: Repair the harness or replace the harness. Stop.Test Step 3. Check for a Short to the +battery.
Check the continuity of switch contacts J1-1, J1-6, J1-40 and J2-12 at the harness.Expected Result:Continuity exists between one of the sources of the battery voltage and the switch circuit.Results:
YES - Continuity exists between one of the sources of the battery voltage and the switch circuit.Repair: The harness has failed. Repair the harness or replace the harness. Stop.
NO - Continuity does not exist between one of the sources of battery voltage and the switch circuit.Repair: The harness 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.