Self-Diagnosis System

Fig. 1 Location Of ECM:

The Electronic Control Module (ECM), located behind the lefthand side of the instrument panel, Fig. 1, monitors vehicle operation by the use of sensors. the sensors output is compared to parameters set in the ECM memory. If these parameters are exceeded, the self-diagnosis system in the ECM detects system failure and identifies the circuit at fault by use of trouble codes.

Fig. 2 Trouble Code Identification:

Fig. 3 Trouble Code Identification:

The check engine lamp, located on the instrument panel, displays the trouble codes. In normal operation the lamp will illuminate when the ignition switch is turned On. However, when the engine is started two different lamp functions can occur. The check engine lamp may turn Off immediately, indicating there is no fault at that time or stay illuminated informing the vehicle operator there is a system failure. If the engine lamp stays illuminated a trouble code will be stored in the ECM memory. When a trouble code is accessed from the ECM memory the check engine lamp will flash in a series indicating the trouble code number Figs. 2 and 3. When multiple system failures occur applicable codes will be indicated three times each. Codes will continue to flash as long as the ignition switch is On, and the diagnostic switch terminals are grounded.