System Description

DESCRIPTION
This MFI engine systems have the latest in technical advances. The on-board diagnostics incorporated with the Powertrain control module are intended to assist the field technician in repairing vehicle problems by the quickest means.

OPERATION
The PCM has been programmed to monitor any different circuits of the fuel injection system. This monitoring is called "on-board diagnosis."

Certain criteria must be met for a trouble code to be entered into the PCM memory. The criteria may be a range of: engine rpm, engine temperature, and/or input voltage to the PCM. If all of the criteria for monitoring a system or circuit are met and a problem is sensed, then a trouble code will be stored in the PCM.

It is Possible that a trouble code for a monitored circuit may not be entered into the PCM memory even though a malfunction has occurred. This may happen when the monitoring criteria have not been met.

The PCM compares input signal voltages from each input device with specifications (the established high and low limits of the range) that are programmed into it for that device. If the input voltage is not within specifications and other trouble code criteria are met, a trouble code will be stored in the PCM memory.