ENGINE AR 1220734 - Caterpillar

Illustration 1 g01517079
Schematic of the "Transmission Lock" switchThis diagnostic code is associated with the "transmission lock" switch. This diagnostic code is recorded when the ECM reads the signal from the switch and the ECM determines that the signal is erratic, intermittent, or incorrect.The possible causes of this diagnostic code are listed below:
Wire (C720-BU) is shorted to the ground circuit while the machine is in operation.
Wire (C720-BU) is shorted to the +battery.
An open circuit exists.
The Transmission Lock Switch has failed.
The ECM has failed. This is unlikely.Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 0626 FMI 02 is active before performing this procedure.Note: Use the 146-4080 Digital Multimeter for the measurements in this procedure.System Response:When the CID 0626 FMI 02 diagnostic code is active the machine will respond in the following manner:
Machine functions will be limited.Note: Before the following Test Steps are performed, check that the speed switch is mounted securely. If the mount of the speed switch is correct and the CID 0626 FMI 02 code is active, proceed to Test Step 1.Test Step 1. VERIFY THE VERSION OF THE SOFTWARENote: Use SIS in order to check for the latest version of the software for the ECM. Record the latest software version for the machine electronic controls.
Verify that the latest software version is loaded in the Machine ECM.
Verify that the ECM modules (valve) are loaded with the latest software.Expected Result:All of the software is up-to-date.Results:
OK - All of the software is up-to-date. Proceed to Test Step 2.
NOT OK - There is a more recent version of the software that is available.Repair: Flash all controls with the latest software release. Refer to Troubleshooting, "Electronic Control Module (ECM) - Flash Program".STOPTest Step 2. CHECK THE HARNESS.
Turn the key start switch to the OFF position.
Inspect the harness.
Check for the proper mating.
Check the exposed wires for nicks and abrasions.
Check for moisture, dirt, or corrosion.
Check the pin and the socket for a proper fit.
Disconnect the machine harness connectors from the Machine ECM.
At the machine harness connector, measure the resistance from connector contact 4 (wire C720-BU) to J2-47 (wire C720-BU) of the Machine ECM. Expected Result:The resistance should be less than 5 ohms.Results:
OK - The resistance is less than 5 ohms. The machine harness is correct. Proceed to test step 3.
NOT OK - The resistance is greater than 5 ohms. There is an open in the machine harness. The open is between the modules for the signal (wire C720-BU).Repair: Repair the machine harness or replace the machine harness.STOPTest Step 3. CHECK IF THE DIAGNOSTIC CODE REMAINS.
Clean the contacts of the harness connectors.
Reconnect all harness connectors.
Observe the status of the diagnostic code.
Operate the machine.
Observe the status of the diagnostic code.Expected Result:The diagnostic code is NO longer active.Results:
YES - The diagnostic code is NO longer active. The diagnostic code does not exist at this time. The initial diagnostic code was probably