MOUNTING AS 7T1819 - Caterpillar

Conditions Which Generate This Code:
Illustration 1 g01945365
Connections of the increment/decrement switch for PTO 2This diagnostic code is associated with the increment/decrement switch for PTO 2. The FMI 04 is recorded when the ECU determines that the voltage is below normal for the circuit. The switch has two inputs to the ECU. Only one input is grounded at any one time. When the switch is in the center position, neither input is grounded. When a circuit is measured with a voltmeter, an open circuit will measure approximately 8 VDC to ground and a closed circuit will measure approximately 0 VDC to ground. The possible causes of this diagnostic code are listed:
Contact "A" (wire Y976-BU) is shorted to ground while contact "C" (wire Y977-BU) is shorted to ground.
The switch has failed.
The ECU has failed. This is unlikely. Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all of the connections in the circuit are clean and secure. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure.The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear these diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 3396 FMI 04 is active before performing this procedure.
Table 1
Status of the Switch    
MODE    Switch Position    J2-46
Y976-BU Circuit    J2-47
Y977-BU Circuit    
Increment     Up     Open     Closed    
Static     Center     Open     Open    
Decrement     Down     Closed     Open    Test Step 1. CHECK THE SWITCH.
Disconnect the switch from the machine harness.
Check for continuity between contact A and contact B of the switch.
Press the switch. Release the switch and check for continuity.
Check for continuity between contact B and contact C of the switch.
Press the switch. Release the switch and check for continuity.Expected Result:The continuity check agrees with Table 1.Results:
OK - The continuity check agrees. Proceed to Test Step 2.
NOT OK - The continuity check does not agree. The switch has failed.Repair: Replace the switch. Verify that the new switch corrects the diagnostic code.STOPTest Step 2. CHECK THE SIGNAL CIRCUITS IN THE HARNESS FOR A SHORT.
Reconnect the switch to the machine harness.
Disconnect the J1 and J2 machine harness connectors from the ECU.
At the machine harness connector for the ECU, check for continuity between contact J2-46 (wire Y976-BU) and contact J2-63 (wire J765-BU).
Press the switch. Release the switch and check for continuity.
At the machine harness connector for