Trouble Codes

In process of controlling various subsystems, the Engine Control Module and Body Computer Module continually monitor operating conditions for possible system malfunctions. By comparing system conditions against standard operating limits certain circuit and component malfunctions can be detected. A 3-digit numerical "Trouble Code" is stored in computer memory when a problem is detected.

These trouble codes can later be displayed by the service technician as an aid in system repair. The occurrence of certain system malfunctions require that the vehicle operator be alerted to the problem so as to avoid prolonged operation of the vehicle under subnormal system operation. Computer controlled diagnostic messages and/or telltales will appear under these conditions which indicate that service is required.

If a particular malfunction would result in unacceptable system operation, the self-diagnostics will attempt to minimize the effect by taking "Failsoft" action. "Failsoft" action refers to any specific attempt by the computer system to compensate for the detected problem. A typical "Failsoft" action would be the substitution of a fixed input value when a sensor is detected to be open or shorted.