Code No.U1538: Rear panel power window-ECU checksum error
COMMENTS ON TROUBLE SYMPTOM
If any abnormality is found with the rear panel power window-ECU, the ETACS-ECU stores the diagnosis code No.U1538.
PROBABLE CAUSES
Malfunction of the rear panel power window-ECU
DIAGNOSIS PROCEDURE
Check whether the diagnosis code is reset.
Check again if the diagnosis code is set to the ETACS-ECU.
(1)Erase the diagnosis code.
(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3)On completion, check that the diagnosis code is reset.
Q.
Is the check result normal?
A poor connection, open circuit or other intermittent malfunction is present in the LIN bus lines between the rear panel power window-ECU and the ETACS-ECU (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points -
How to Cope with Intermittent Malfunctions ).
A poor connection, open circuit or other intermittent malfunction is present in the LIN bus lines between the rear panel power window-ECU and the ETACS-ECU (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points -
How to Cope with Intermittent Malfunctions 
Replace the rear panel power window-ECU.