DIAGNOSIS SYSTEM Description The ECU contains a built-in self-diagnosis system by which troubles with the engine signal network are detected and a "CHECK ENGINE" warning light on the instrument panel flashes (Code Nos. 12, 13, 14, 21, 22, 31, 32, 42, 52 and 53). A "CHECK ENGINE" warning light on the instrument panel informs the driver that a malfunction has been detected. The light goes out automatically when the malfunction has been cleared. The diagnostic code can be read by the number of blinks of the "CHECK ENGINE" warning light when terminals T and E1 are short-circuited. "CHECK ENGINE" WARNING LIGHT CHECK 1. The "CHECK ENGINE" warning light will come on when the ignition switch is placed at ON and the engine is not running. 2. When the engine is started, the "CHECK ENGINE" warning light should go out. If the light remains on, the diagnosis system has detected a malfunction in the system. OUTPUT OF DIAGNOSTIC CODES Initial Conditions • Battery voltage above 11 volts. • Throttle valve fully closed (throttle position sensor IDL points closed). • Transmission in P or N range. • Air conditioner switch OFF. • Engine at normal operating temperature. 1. Turn the ignition switch to ON. Do not start the engine. 2. Using a sub-wire, short terminals of the check connector.