PARK BRAKE CHAMBER ASSEMBLY 6U8893 - Caterpillar

Illustration 1 g02729315
Schematic of the Cat Data Link Circuit
This diagnostic code is recorded when the brake ECM reads a diagnostic code that is internal to the Chassis ECM for more than 5 seconds.The possible causes of this diagnostic code are listed:
There is a poor electrical connection.
The chassis ECM is failed. There are no serviceable parts within the ECM.Note: It may be possible to communicate using the Cat ET. If the Cat ET will not communicate, then try the "WinFlash" program. Attempt to reflash the ECM.System Response:This failure results in events that are logged against an ECM that cannot be explained. The Brake ECM cannot communicate with the Chassis ECM or the Chassis ECM appears to communicate intermittently.Test Step 1. VERIFY THAT THE DIAGNOSTIC CODE IS PRESENT.
Ensure that the diagnostic code CID 1273 FMI 12 is active.
Turn the key start switch and the disconnect switch to the OFF position.
Remove connectors J1 and J2 from the ECM and reconnect connectors J1 and J2 to the ECM.
Turn the key start switch and the disconnect switch to the ON position.
Clear all inactive diagnostic codes.
Operate the machine.
Check whether CID 1273 FMI 12 is active. Expected Result:The CID 1273 FMI 12 is NOT active.Results:
OK - The CID 1273 FMI 12 is NOT active.Repair: The diagnostic code is NOT present. The initial diagnostic code was probably caused by a poor electrical connection. This could have been a short at one of the harness connectors that was disconnected and then reconnected.
NOT OK - The CID 1273 FMI 12 is present. The ECM may have failed.Repair: It is unlikely that the chassis ECM has failed. Exit this procedure and perform this diagnostic code procedure again. If the cause of the diagnostic code is not found, replace the chassis ECM. See Service Manual, "ECM - Replace".