ECM/PCM Code Description

Fig. 2 ECM diagnostic codes & diagnostic code comments:

Fig. 3 BCM diagnostic codes:

The ECM and BCM continually monitor operating conditions of their controlled systems for possible malfunctions. When a problem is detected, a two-digit numerical ``trouble code,'' Figs. 2 and 3, is stored in computer memory. These codes can be displayed as aid in system repair. Any malfunctions which the vehicle operator should be aware of will illuminate ``Service Now'' or ``Service Soon'' warning lamps on the dashboard.
If a malfunction which would result in unacceptable system operation is encountered, the self-diagnostics will minimize the effect by taking ``failsoft'' action to compensate for the detected problem. A typical ``failsoft'' action, for example, would be the substitution of a fixed input value when a sensor is detected to be open or shorted.