Self-Diagnosis System

Fig. 3 Speed Control Self-diagnosis Description & Display Chart:

The self-diagnosis function senses a malfunction of the automatic speed control system (ASC) not made by the driver. To diagnose which circuit or what operation caused the malfunction of the ASC system, connect a suitable voltmeter and a multi-use tester to the diagnosis harness connector. The display of the malfunction data starts, if vehicle speed decreases to less than approximately 12 mph after the malfunction of ASC system, and stops if vehicle speed increases to approximately 12 mph or higher, Fig. 3.
The ASC system performs control functions for setting or cancellation of fixed speed driving based on data provided by input signals. When the ASC system is canceled, the causes is memorized in a separate circuit by the (ECU). If the computer (ECU) power supply, ignition switch and main switch is Off, the memorized diagnosis codes are erased. The power supply must be left On until checking is completed.