I had my ECU replaced today. The part number is 89222-00E011. Here is the TSIB info.
EL002-04 - Power Back Door Inoperative (Updated April 5, 2004)
Serial Numbers: 2WD - Japan 27908, Canada 5492; 4WD - Japan 54350, Canada 8100
Symptoms are intermittent periods of inoperation of the power back door unit. Manual operation of the door may fix the problem temporarily. Computer does not throw a DTC code. Fix is a new ECU computer control module for the back door.