• The engine ECU contains a built-in self-diagnosis system by which troubles with the engine signal network are detected and a check engine warning light in the combination meter lights up. j
By analyzing various signals as shown in the later table (See page Dl—12) the engine ECU detects system malfunctions relating to the sensors or actuators.
In the normal mode, the self-diagnosis system monitors 9 items, indicated by code No. as shown in Dl—12. A check engine warning light informs the driver that a malfunction has been detected. The engine ECU stores the code(s) until it is cleared by removing the F-HTR fuse with the ignition switch off.
The DTC (diagnostic trouble code) can be read by the number of blinks of the check engine warning light when TE1 and E1 terminals on the check connector are connected. When 2 or more codes are indicated, the lowest number (code) will appear first. In the test mode, 5 items, indicated by code No. as shown in Dl—12 are monitored. If a malfunction is detected in any one of the systems indicated by code Nos. 22, 24, 35 and 41 the engine ECU lights the check engine warning light to warn the technician that malfunction has been detected. In this case, TE2 and E1 terminals on the check connector should be connected as shown later (See page DI-3).
In the test mode, even if the malfunction is corrected, the malfunction code is stored in the engine ECU memory even when the ignition switch is off. This also applies to the normal mode. The diagnostic mode (normal or test) and the output of the check engine warning light can be selected by connecting the TE1, TE2, and E1 terminals on the check connector, as shown later. s A test mode function has been added to the functions of the self-diagnosis system of the normal mode for the purpose of detecting malfunctions such as poor contact, which are difficult to detect in the normal mode. This function fills up the self-diagnosis system. The test mode can be implemented by the technician following the appropriate procedures of check terminal connection and operation described later (See page DI-3).
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