SPECIAL AR 3157328 - Caterpillar

Illustration 1 g02570817
Connections of the Transmission Direction Switch
The Transmission Direction Switch is integral to the transmission shift assembly. The Transmission Direction Switch has three inputs to the ECM. During normal operation, two of the inputs are open and the other input is grounded. The input which is grounded depends on the position of the switch. Before you perform this procedure, refer to table 1 in order to determine the connector and the contacts that correspond to the faulty circuit.Possible causes of the diagnostic code are listed:
There is a harness fault.
There is a failed switch.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.Note: 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 0623 FMI 04 is active before performing this procedure.Note: Use a digital multimeter for the measurements in this procedure.
Table 1
Status of Direction Switch
Switch Position G755-GY(Grey) Circuit
R Switch
J2-28 G763-PU(Purple) Circuit
N Switch
J2-23 G750-BU(Blue) Circuit
F Switch
J2-49
R Closed Open Open
N Open Closed Open
F Open Open Closed System Response:The machine will lock in neutral until the diagnostic condition is corrected.Test Step 1. CHECK FOR AN OPEN CIRCUIT.
Ensure that the diagnostic code is active.
Disconnect the connector of the transmission direction switch from the machine harness. Expected Result:The active diagnostic code changes from "04" to "03".Results:
YES - The transmission direction switch or the switch harness is failed. Repeat Test Step 1 in order to verify the failure of the transmission direction switch.Repair: Repair the switch or replace the switch or the switch harness.STOP
NO - The diagnostic code is active. The transmission direction switch is not the cause of this diagnostic code. Proceed to Test Step 2.Test Step 2. CHECK THE HARNESS CIRCUIT.This test checks the continuity of the entire harness circuit that is faulty. The transmission direction switch which was previously checked in Test Step 1 is included in this test.
Turn the key start switch and the disconnect switch to the OFF position.
Connect the transmission direction switch to the machine harness.
Disconnect the machine harness connector J1 from the ECM.
At the machine harness connector for the ECM, check the continuity to ground of the switch contacts for the transmission direction switch that is activated and switch that is not activated. Refer to table 1 for the correct switch status. Expected Result: The continuity check does NOT agree with table 1.Results:
YES - The continuity check does NOT agree with the previous table. The harness circuit is faulty. There is a short to ground in the machine harness between the ECM and the transmission direction switch.Repair: Repair the machine harness or replace the machine harness.STOP
NO - The continuity