Code 85 - Prom Error & Code 87 - EEPROM Error
WARNING: This page is about a different car, the 1993 Cadillac Fleetwood. However, it is still accessible from the selected car via links, so may be relevant.
Ensure all ECM connectors are fully inserted in socket. If okay, have ECM reprogrammed using appropriate equipment. If equipment is not available, have ECM serviced through dealership.