PIN 2651096 - Caterpillar

Illustration 1 g00590113
Schematic for the Transmission Auto/Manual SwitchThe transmission auto/manual switch has four inputs to the power train electronic control module (ECM). During normal operation, one input is grounded and the other inputs are open. The valid combinations for each switch position are shown in table 1 that follows. If an invalid combination is detected by the power train ECM, a circuit failure is present. If all four switch inputs to the power train ECM are open a fault will result. The fault is set in 5 seconds. After the fault has been corrected, the fault will be cleared within 1 second.
Table 1
Auto/Manual Switch Status    
Switch Position     973-BR
J2-05     977-YL
J1-33     H728-GN
J1-35     H729-WH
J1-38    
AUTO Speed 2     Open     Open     Open     Ground    
AUTO Speed 3     Open     Open     Ground     Open    
AUTO Speed 4     Open     Ground     Open     Open    
Manual     Ground     Open     Open     Open    Note: Ensure that the desired fault code is active.Note: The following procedure can create other faults that can be detected by the power train ECM. Ignore these created faults and clear the created faults when the fault is corrected.Possible causes of this diagnostic code are listed:
There is a harness fault.
There is a failed switch.System Response:The machine response is listed:
The autoshift is disabled.Test Step 1. CHECK FOR AN OPEN CIRCUIT.
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the machine harness from the power train ECM.
At the machine harness connector for the power train ECM, check the continuity to ground of the open contacts and the grounded contact for each position of the transmission auto/manual switch. Activate and deactivate each position of the transmission auto/manual switch. Refer to table 1 for the correct continuity.Expected Result:The continuity check does not agree with the information that is found in table 1.Results:
YES - The continuity check does NOT agree with the previous table. The harness or the transmission auto/manual switch is faulty. Proceed to Test Step 2.
NO - The continuity check agrees with the previous table. Proceed to Test Step 3.Test Step 2. CHECK THE TRANSMISSION AUTO/MANUAL SWITCH.
Disconnect the machine harness from the transmission auto/manual switch.
Check the continuity to ground of the open contacts and the grounded contact for each position of the transmission auto/manual switch. Activate and deactivate each position of the transmission auto/manual switch. Refer to table 1 for the correct continuity.Expected Result:The continuity check does not agree with table 1.Results:
YES - The continuity check does not agree with the previous table. The transmission auto/manual switch is faulty.Repair: Repair the switch or replace the switch. Stop.
NO - The continuity check agrees with the previous table.Repair: Repair the machine harness or replace the machine harness. Stop.Test Step 3. CHECK FOR A SHORT TO THE +BATTERY.
At the machine harness connector for the power train ECM, check the continuity from each switch contact to the contacts J1-1, J1-6, J1-40 and J2-12.Expected Result:Continuity exists