BRACE AS 1U0105 - Caterpillar

Conditions Which Generate This Code:
Illustration 1 g01944263
Connections of the gear hold switchThis diagnostic code is associated with the gear hold switch. The FMI 04 is recorded when the ECU determines that the voltage is below normal for the circuit. The switch is a momentary switch.The possible causes of this diagnostic code are listed:
The signal circuit (wire T921-PK) is always 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 1292 FMI 04 is active before performing this procedure.
Table 1
Status of the Switch    
MODE    Switch Position    J1-35
T921-PK Circuit    
Released     Up     Open    
Pressed     Down     Closed    Test Step 1. CHECK THE SWITCH.
Disconnect the switch from the machine harness.
Check for continuity between contact 1 and contact 2 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 J1-35 (wire T921-PK) and contact J2-22 (wire 993-BR).
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.Repair: Reconnect the machine harness connectors. Verify that the diagnostic code has been corrected. If the cause of the problem is not found, contact your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECU requires replacement, refer to Testing and Adjusting, KENR8292, "Electronic Control Unit - Replace".STOP
NOT OK - The continuity check does not agree.Repair: There is a short in the machine harness. Repair the machine harness or replace the machine harness.STOP