Code 53
WARNING: This page is about a different car, the 1995 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.
DRB displays INTERNAL PCM FAILURE. Condition is: Powertrain Control Module (PCM) detects internal failure.
DRB displays PCM FAILURE SPI COMMUNICATION. Condition is: Powertrain Control Module (PCM) detects Serial Peripheral Interface (SPI) communications failure.