Toyota 22R-E Service Manual page 447

EG2–170
ENGINE – MFI SYSTEM
DIAGNOSIS SYSTEM
DESCRIPTION
The ECM contains a built–in self diagnosis system by which troubles with the engine signal
network are detected and a malfunction indicator lamp on the combination meter lights up.
By analyzing various signals as shown in the later table (See pages EG2–176 and 177) the ECM
detects system malfunctions relating to the sensors of actuator.The self–diagnosis system has
two modes, a normal mode and a test mode.
If a malfunction is detected when in the normal mode, the ECM lights up the malfunction indicator
lamp to inform the driver of the occurrence of a malfunction. (For some codes the light does not
come on.) The light goes off automatically when the malfunction has been repaired. But the
diagnostic trouble code(s) remains stored in the ECM memory (except for code Nos. 43, 51 and
53). The ECM stores the code(s) until it is cleared by removing the EFI fuse with the ignition
switch off.
The diagnostic trouble code(s) can be read by the number of blinks of the malfunction indicator
lamp when TE1 and E1 terminals on the DLC1 are connected. When 2 or more codes are
indicated, the lowest number (code) will appear first.
If a malfunction is detected when in the test mode, the ECM lights up the malfunction indicator
lamp to inform the technician of the occurrence of a malfunction (except for code Nos. 42, 43 and
51). In this case, TE2 and E1 terminals on the DLC1 should be connected as shown later. (See
page EG2–173)
In the test mode, even if the malfunction is corrected, the malfunction code is stored in the ECM
memory even when the ignition switch is off (except code Nos. 42, 43, 51 and 53). This also
applies in the normal mode. The diagnostic mode (normal or test) and the output of the
malfunction indicator lamp can be selected by connecting the TE 1, TE2 and E 1 terminals on the
DLC1, as shown later.
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 contacts, which are difficult to
detect in the normal mode. This function fills up the self diagnosis system. The test mode can be
implemented if technicians follow the procedure described later.
(See page EG2–173).