Diagnosis System - Toyota 3VZ–FE Troubleshooting Manual

EG–320
ENGINE TROUBLESHOOTING

DIAGNOSIS SYSTEM

DESCRIPTION
The ECM contains a built–in self–diagnosis system by which
troubles with the engine signal network are detected and a Mal-
function Indicator Lamp on the instrument panel lights up.
By analyzing various signals as shown in the later table (See page
EG–324) the ECM detects system malfunctions relating to the
sensors or actuators.
In the normal mode, the self–diagnosis system monitors 21
(California specification vehicles) or 18 (Other than California
specification vehicles) items, indicated by code No. as shown in
EG–324. A Malfunction Indicator Lamp informs the driver that a
malfunction has been detected. 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. 16 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 can be read by the number of blinks
of the Malfunction Indicator Lamp when TE1 and E1 terminals on
the data link connector 2 or data link connector 1 are connected.
When 2 or more codes are indicated, the lowest number (code) will
appear first.
In the test mode, 13 (California specification vehicles) or 10 (Other
than California specification vehicles) items, indicated by code No.
as shown in EG–324 are monitored. If a malfunction is detected
in any one of the systems indicated by code Nos. 13, 21, 22, 24,
25, 26, 27, 28, 31, 32, 41, 42, and 71 (California specification ve-
hicles) or 13, 21, 22, 24, 25, 28, 31, 32, 41 and 42 (Other than
California specification vehicles) the ECM lights the Malfunction
Indicator Lamp to warn the technician that malfunction has been
detected. In this case, TE2 and E1 terminals on the data link con-
nector 2 or data link connector 1 should be connected as shown
later. (See page EG–322)
In the test mode, even if the malfunction is corrected, the malfunc-
tion code is stored in the ECM memory even when the ignition
switch is off (except code Nos. 43 and 51). 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 TE1, TE2 and E1 terminals on the data link connector 1 or data
link connector 2, 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 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 opera-
tion described later. (See page EG–322)
– DIAGNOSIS SYSTEM