DI00H±16
FI0534
I12054
TOYOTA Hand±Held tester
DLC3
± DIAGNOSTICSENGINE
DI±3
2001 PRIUS (RM778U)
PRE±CHECK
1. DIAGNOSIS SYSTEM
(a) Description
When troubleshooting OBDII vehicles, the only dif-
ference from the usual troubleshooting procedure
is that you connect to the vehicle the OBDII scan
tool complying with SAE J1978 or TOYOTA hand±
held tester, and read off various data output from
the vehicle's ECM.
OBDII 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 Code (DTC) prescribed
by SAE J2012 are recorded in the ECM memory
(See page DI±14).
If the malfunction does not reoccur in 3 consecutive trips, the
MIL goes off automatically but the DTCs remain recorded in the
ECM memory.
When DTC P3190, P3191 are detected and the re-
main of the fuel is little, the computer judges the
cause as a fuel shortage, and after the next trip,
when the supply of fuel is confirmed, it turns off MIL,
but the memory of DTC still remains.
To check the DTCs, connect the TOYOTA hand±
held tester or OBDII scan tool to Data Link Connec-
tor 3 (DLC3) on the vehicle. The TOYOTA hand±
held tester or OBDII scan tool also enables you to
erase the DTCs and check freezed frame data and
various forms of engine data. (For operating instruc-
tions, see the OBDII 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 DI±14).
