Pre-Check - Toyota ZZT230 series Repair Manual

C H E C K
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DIAGNOSTICS ENGINE

PRE-CHECK

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DIAGNOSIS SYSTEM
1 .
Description
(a)
When troubleshooting OBD II vehicles, the only dif­
ference from the usual troubleshooting procedure
is that you connect to the vehicle the OBD II scan
tool complying with SAE J1 978 or TOYOTA hand­
held tester, and read off various data output from
the vehicle's ECM.
OBD II regulations require that the vehicle's on­
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board computer lights up the Malfunction Indicator
Lamp (MIL) on the instrument panel when the com·
puler detects a malfunction in the emission control
system/components or in the power train control
components which affect vehicle emissions, or a
malfunction in the computer. In addition to the MIL
lighting up when a malfunction is detected, the ap-
plicable Diagnost'1c Trouble Code (DTC) prescribed
by SAE
(See page Dl-14).
If the malfunction does not reoccur in 3 consecutive, the MIL
goes off automatically but the OTCs remain recorded in the
ECM memory.
To check the DTCs, connect the OBD II scan tool or
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TOYOTA hand-held tester to Data Link Connector
3 (DLC3) on the veh'1cle. The OBD II scan tool or
TOYOTA hand-held tester also enables you to
erase the DTCs and check freezed frame data and
various forms of engine data (For operating instruc­
tions, see the 080 II scan tool's instruction book.).
DTCs include SAE controlled codes and manufac­
turer controlled codes. SAE controlled codes must
be set as prescribed by the SAE, while manufactur­
er controlled codes can be set freely by the
manufacturer within the prescribed limits (See DTC
chart on page Dl-14).
J2012
are recorded in the ECM memory
Dl-3