2001 TOYOTA PRIUS check engine

± DIAGNOSTICSENGINE
DI±135
2001 PRIUS (RM778U)
DTC P1437 Vacuum Line Malfunction
CIRCUIT DESCRIPTION
Refer to DTC P1436 on page DI±133.
DTC No.DTC Detecting ConditionTrouble Area
P1437
With cold start when the water temperature and intake air
temperature were ± 10 °C (14 °F) to 40 °C (104 °F), and
when the water temperature has reached 45 °C (113 °F) or
more and the engine load factor has become more than 30
%, the negative pressure has abnormality.
Vacuum line

VSV for HC adsober and catalyst system

Vacuum sensor for HC adsober and catalyst system

Check valve
INSPECTION PROCEDURE
TOYOTA hand±held tester:
1 Check vacuum hoses and tube between intake manifold and actuator.
CHECK:
(a) Check that the vacuum hoses is connected correctly.
(b) Check the vacuum hose for looseness and disconnection.
(c) Check the vacuum hose and tube for cracks, holes and damage.
(d) Check the vacuum hose for clog.
NG Repair or replace.
OK
2 Check for open and short in harness and connector between VSV (for HC adsob-
er and catalyst system) and ECM (See page IN±41).
NG Repair or replace harness or connector.
OK
3 Check VSV (for HC adsorber and catalyst system) (See page SF±47).
NG Replace VSV.
OK
DI7T1±01

DI±136
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
4 Check vacuum stored in vacuum hose between check valve and actuator.
PREPARATION:
(a) Disconnect the vacuum hose from the pressure sensor for HC adsober and catalyst system.
(b) Connect the MITYVAC (Hand±held vacuum pump) to the vacuum hose.
(c) Connect the TOYOTA hand±held tester to the DLC3.
CHECK:
(a) VSV (for HC adsober and catalyst system) is operate by TOYOTA hand±held tester.
(b) Apply vacuum of 55 kPa (420 mmHg, 16.24 in.Hg).
(c) Check that the vacuum after 30 sec.
OK:
The vacuum is 25 Kpa (188 mmHg, 7.38 in.Hg) or more.
OK Check and replace vacuum hose between in-
take manifold and actuator.
NG
5 Check check valve.
NG Replace check valve.
OK
6 Check stored vacuum of VSV.
NG Replace VSV (for HC adsober and catalyst sys-
tem).
OK
7 Check stored vacuum of actuator(See page EC±13).
NG Replace actuator.
OK

± DIAGNOSTICSENGINE
DI±137
2001 PRIUS (RM778U)
Check and replace vacuum hose and tube
between check valve and actuator.
OBD II scan tool (excluding TOYOTA hand±held tester):
1 Check vacuum hoses and tube between intake manifold and actuator.
CHECK:
(a) Check that the vacuum hoses is connected correctly.
(b) Check the vacuum hose for looseness and disconnection.
(c) Check the vacuum hose and tube for cracks, holes and damage.
(d) Check the vacuum hose and tube for clog.
NG Repair or replace.
OK
2 Check for open and short in harness and connector between VSV (for HC adsob-
er and catalyst system) and ECM (See page IN±41).
NG Repair or replace harness or connector.
OK
3 Check VSV (for HC adsober and catalyst system) (See page SF±47).
NG Replace VSV.
OK

A14019
ONHCC
DI±138
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
4 Check vacuum stored in vacuum hose between check valve and actuator.
PREPARATION:
(a) Remove the ECM with connector still connected (See
page SF±62).
(b) Disconnect the vacuum hose from the vacuum sensor (for
HC adsober and catalyst system).
(c) Connect the MITYVAC (Hand±held vacuum pump) to the
vacuum hose.
CHECK:
(a) Connect the terminal HCC of the ECM and body ground.
(b) Apply a vacuum of 55 kPa (420 mmHg, 16.24 in.Hg).
(c) Check that the vacuum after 30 sec.
OK:
The vacuum is 25 Kpa (188 mmHg, 7.38 in.Hg) or
more.
OK Check and replace vacuum hose between
check valve and actuator.
NG
5 Check check valve.
NG Replace check valve.
OK
6 Check stored vacuum of VSV (See page SF±47).
NG Replace VSV for HC adsober and catalyst sys-
tem.
OK

± DIAGNOSTICSENGINE
DI±139
2001 PRIUS (RM778U)
7 Check stored vacuum of actuator (See page EC±13).
NG Replace actuator.
OK
Check and replace vacuum hose and tube
between check valve and actuator.

A14010
(±) (+)SPHV
A07133
4.5 ± 5.5 V
0
DI±142
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check voltage between terminal SPHV of ECM and body ground.
PREPARATION:
(a) Remove the ECM with connector still connected (See
page SF±62).
(b) Drive the vehicle at 20 km/h (12 mph).
CHECK:
Measure the voltage between SPHV of engine ECU connector
and body ground.
OK:
Voltage is generated intermitlently.
OK Replace engine ECU.
NG
2 Check for open and short in harness and connector between SPHV of ECM and
SPDO of HV ECU.
NG Repair or replace harness or connector.
OK
Replace HV ECU.

A13634
LOCK
BATT
(±)
(+)
A13630
Engine Room J/B
EFI Fuse
DI±144
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
1 Check voltage between terminal BATT of ECM connector and body ground.
PREPARATION:
Remove the ECM with connector still connected (See page
SF±62).
CHECK:
Measure voltage between terminal BATT of the ECM connector
and body ground.
OK:
Voltage: 9 ± 14 V
OK Check and replace ECM (See page IN±41).
NG
2 Check EFI fuse.
PREPARATION:
Remove the EFI fuse from the engine room J/B.
CHECK:
Check continuity of EFI fuse.
OK:
Continuity
NG Check for short in all the harness and
components connected to EFI fuse.
OK
Check and repair harness or connector
between battery and EFI fuse and ECM
(See page IN±41).

A14011
ON
HTE+
HTE±(±) (+)
A14012
2V/
Div.
GND
2m sec/
Div.
± DIAGNOSTICSENGINE
DI±147
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check voltage between terminal HTE+ and HTE± of ECM.
PREPARATION:
(a) Remove the ECM with connector still connected (See
page SF±62).
(b) Turn the ignition swith ON.
CHECK:
Measure voltage between terminal HTE+ and HTE± of the
ECM.
OK:
Reference: INSPECTION USING OSCILLOSCOPE
Turn the ignition swith ON, check waveform between terminals
HTE+ and HTE± of the ECM.
HINT:
The correct waveform is as shown.
OK Replace ECM.
NG
2 Check for open and short in harness and connector between HTE+ and HTE± of
ECM and HTE+ and HTE± of HV ECU (See page IN±41).
OK Replace HV ECU.
NG
Repair or replace harness or connector.