SCREEN AS-SUCTION 4H2978 - Caterpillar

MID 027 CID 3381 FMI 03Conditions Which Generate This Code:
Illustration 1 g01991687
Connections of the transmission shifter selector switch
The transmission shifter selector switch has two inputs to the ECM. During normal operation, one of the inputs is open. The other 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. An FMI 03 diagnostic code is recorded when the status of both the inputs are open.The possible causes of this diagnostic code are listed below:
The return circuit (wire 993-BR(Brown)) is open.
Contact "A" (wire 961-BR(Brown)) is open while contact "C" (wire 962-OR(Orange)) is open.
The switch has failed.
The ECM 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 3381 FMI 03 is active before performing this procedure.
Table 1
Status of the Switch
MODE Switch Position J2-35
961-BR(Brown) Circuit J2-40
962-OR(Orange) Circuit
Primary Up Open Closed
Secondary Down Closed Open Test Step 1. CHECK THE GROUND CIRCUIT FOR AN OPEN
Turn the disconnect switch and the keyswitch to the OFF position.
Disconnect the switch from the machine harness.
Measure the resistance between frame ground and contact B (wire 993-BR(Brown)) at the connector for the switch. Expected Result:The resistance should be less than 5 ohms.Results:
OK - The resistance is less than 5 ohms. Proceed to Test Step 2.
NOT OK - The resistance is greater than 5 ohms.Repair: The return circuit (wire 993-BR(Brown)) is open in the machine harness. Repair the machine harness or replace the machine harness.STOPTest Step 2. CHECK THE SWITCH
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 3.
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 3. CHECK THE SIGNAL CIRCUITS IN THE HARNESS FOR AN OPEN
Reconnect the switch to th