DI8B2-01
FI0534
A06134
TOYOTA Hand-Held Tester
-
DIAGNOSTICS
ENGINE
DI-3
157
Author:
Date:
2001 SIENNA (RM787U)
PRE-CHECK
1.
DIAGNOSIS SYSTEM
(a)
Description
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 J1978 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-
board computer lights up the Malfunction Indicator
Lamp (MIL) on the instrument panel when the com-
puter detects a malfunction in the emission control
system/components or in the powertrain 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 Diagnostic Trouble Codes (DTC) pre-
scribed by SAE J2012 are recorded in the ECM
memory (See page
).
If the malfunction does not reoccur in 3 consecutive trips, the
MIL goes off but the DTCs remain recorded in the ECM memory.
To check the DTC, connect the OBD II scan tool or
TOYOTA hand-held tester to Data Link Connector
3 (DLC3) on the vehicle. The OBD II scan tool or
TOYOTA hand-held tester also enables you to
erase the DTC and check freezed frame data and
various forms of engine data (For operating instruc-
tions, see the OBD II scan tool’s instruction book.).
DTC 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
).