On-Board Diagnostic System Description

All 1987 Caravan and Voyager vans equipped with 2.5L engines and electronic fuel injection have an On-Board diagnostic system. This system allows faster diagnostic times in determining where the problem is. The engine control module monitors critical input and output circuits that are related to engine functions. If the on-board diagnostic system senses that one of the circuits is bad during a predetermined amount of time, the monitoring cycle will consider this a real problem and set a fault code.