2001 TOYOTA PRIUS Service Repair Manual

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.

F02660
HV ECUECM
ESTPR±Y 8
16
E9 H14ESTP DI±148
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
DTC P1637 ESTP Signal Malfunction
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
P1637When signal of ESTP is not input from the HV ECU for 2 sec.
or more
Wire harness

HV ECU

ECM
WIRING DIAGRAM
DI7T5±01

A14013
START
ESTP
± DIAGNOSTICSENGINE
DI±149
2001 PRIUS (RM778U)
INSPECTION PROCEDURE
1 Check voltage between terminal ESTP of ECM and body ground.
PREPARATION:
(a) Remove the ECM with connector still connected (See
page SF±62).
(b) Start the engine.
CHECK:
Measure voltage between terminal ESTP of ECM and body
ground.
OK:
Voltage: 9 ± 14 V
OK Replace ECM.
NG
2 Check for open and short in harness and connector between ESTP of ECM and
HV ECU (See page IN±41).
OK Replace HV ECU.
NG
Repair or replace harness or connector.

DI±150
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
DTC P1656 OCV Circuit Malfunction
CIRCUIT DESCRIPTION
Refer to DTC P1349 on page DI±121.
DTC No.DTC Detecting ConditionTrouble Area
P1656
P1663Open or short in oil control valve circuit

Open or short in oil control valve circuit

Oil control valve

ECM
WIRING DIAGRAM
Refer to DTC P1349 on page DI±121.
INSPECTION PROCEDURE
HINT:
Read freeze frame data using TOYOTA hand±held tester or OBD II scan tool. Because freeze frame records
the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the engine warmed up or not, the air±fuel ratio lean or rich, etc.
at the time of the malfunction.
TOYOTA hand±held tester
1 Check OCV circuit.
PREPARATION:
(a) Start the engine and warmed it up.
(b) Connect the TOYOTA hand±held tester and select VVT from ACTIVE TEST menu.
CHECK:
Check the engine speed when operate the OCV by the TOYOTA hand±held tester.
OK:
VVT system is OFF (OCV is OFF): Normal engine speed
VVT system is ON (OCV is ON): Rough idle or engine stalled
OK Check for intermittent problems
(See page DI±3).
NG
DI6VO±02

A14062
± DIAGNOSTICSENGINE
DI±151
2001 PRIUS (RM778U)
2 Check operation of OCV.
PREPARATION:
(a) Start the engine and warmed it up.
(b) Disconnect the OCV connector.
(c) Apply battery positive voltage between terminals of the
OCV.
CHECK:
Check the engine speed.
OK:
Rough idle or engine stalled.
NG Replace OCV.
OK
3 Check voltage between terminals OCV+ and OCV± of ECM connector
(See page DI±121).
NG Check and replace ECM (See page IN±41).
OK
4 Check for open and short in harness and connector between OCV and ECM
(See page IN±41).
NG Repair or replace.
OK
Check for intermitent problems
(See page DI±3).

A14062
DI±152
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
OBD II scan tool (excluding TOYOTA hand±held tester)
1 Check operation of OCV.
PREPARATION:
(a) Start the engine and warmed it up.
(b) Disconnect the OCV connector.
(c) Apply battery positive voltage between terminals of the
OCV.
CHECK:
Check the engine speed.
OK:
Rough idle or engine stalled
NG Replace OCV.
OK
2 Check voltage between terminals OCV+ and OCV± of ECM connector
(See page DI±121).
NG Check and replace ECM (See page IN±41).
OK
3 Check for open and short in harness and connector between OCV and ECM
(See page IN±41).
NG Repair or replace.
OK
Check for intermitent problems
(See page DI±3).