2001 TOYOTA PRIUS stop start

DI±8
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
4. FAIL±SAFE CHART
If any of the following codes is recorded, the ECM enters fail±safe mode.
DTC No.Fail±Safe OperationFail±Safe Deactivation Conditions
P0100Ignition timing fixed at 5° BTDCReturned to normal condition
P0110Intake air temp. is fixed at 20°C (68°F)Returned to normal condition
P0115Engine coolant temp. is fixed at 80°C (176°F)Returned to normal condition
P0120VTA is fixed at 0°
The following condition must be repeated at least 2 times
consecutively
0.1 V
VTA
0.95 V
P0135
P0141The heater circuit in which an abnormality is detected is
turned offIgnition switch OFF
P0325Max. timing retardationIgnition switch OFF
P1300
P1305
P1310
P1315
Fuel cutIGF signal is detected for 2 consecutive ignitions
5. CHECK FOR INTERMITTENT PROBLEMS
TOYOTA hand±held tester only:
By putting the vehicle's ECM in check mode, 1 trip detection logic is possible instead of 2 trip detection logic
and sensitivity to detect open circuits is increased. This makes it easier to detect intermittent problems.
(1) Clear the DTC (See step 3).
(2) Set the check mode (See step 3).
(3) Perform a simulation test (See page IN±30).
(4) Check the connector and terminal (See page IN±41).
(5) Handle the connector (See page IN±41).
6. BASIC INSPECTION
When the malfunction code is not confirmed in the DTC check, troubleshooting should be performed in the
order for all possible circuits to be considered as the causes of the problems. In many cases, by carrying
out the basic engine check shown in the following flow chart, the location causing the problem can be found
quickly and efficiently. Therefore, use of this check is essential in engine troubleshooting.
1 Is battery positive voltage 11 V or more when engine is stopped?
NO Charge or replace battery.
YES
2 Does engine start?
NO Go to step 6.
YES

A14050
G±R
(Shielded)
512
IA2
1A
3
2
1
1EFI
3
B±G
F13B
MAIN
FL Block No. 1
BatteryEngine Room J/B
BR 1F
1K 1
2 3
11BW±B4
EB A
J7
J/C 1 2M1 Mass
Air Flow
Meter
A A 3
BE9
E810
VG
EVGECM
EFI
Relay
IEMREL
E8 G±R
19 G
R
F18 FL Block No. 2
F12W±B
J1
J/CJ9
J/C A
AW±B25
DI±24
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
WIRING DIAGRAM
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.
1 Connect OBD II scan tool or TOYOTA hand±held tester, and read value of mass
air flow rate.
PREPARATION:
(a) Connect the OBD II scan tool or TOYOTA hand±held tester to the DLC3.
(b) Turn ignition switch ON and push the OBD II scan tool or TOYOTA hand±held tester main switch ON.
(c) Start the engine.
CHECK:
Read mass air flow rate on the OBD II scan tool or TOYOTA hand±held tester.
RESULT:
Type IType II
Mass air flow rate (gm/sec.)0.0271.0 or more

DI±36
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
DTC P0116 Engine Coolant Temp. Circuit Range/
Performance Problem
CIRCUIT DESCRIPTION
Refer to DTC P0115 on page DI±32.
DTC No.DTC Detecting ConditionTrouble Area
When the engine starts, the water temp. is ±7°C (20°F) or
less. And, 20 min. or more after the engine starts, the engine
temp. sensor value is 5°C (41°F) or less (2 trip detection logic)
When the engine starts, the water temp. is between ±7°C
(20°F) and 10°C (50°F). And, 5 min. or more after the engine
starts, the engine coolant temp. sensor value is 5°C (41°F) or
less. (2 trip detection logic)
P0116When the fluctuations in the engine coolant tempeerature are
within 3 °C (37 °F)before and afrer the follwing conditions are
met:
1. IDL OFF time  250 sec.
2. Vehicle speed change of 30 km/h (19 mph) or more occurs
10 times or more.
3. 35 °C (95 °F)
Engine coolant temperature when the
ignition switch is turned ON < 60 °C (140 °F)
4. Intake air temperature after starting the engine  ±6.7 °C
(20 °F)
Engine coolant temp. sensor

Cooling system
INSPECTION PROCEDURE
HINT:

If DTC P0115 and P0116 are output simultaneously, engine coolant temp. sensor circuit may be open.
Perform troubleshooting of DTC P0115 first.

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.
1 Are there any other codes (besides DTC P0116) being output?
YES Go to relevant DTC chart.
NO
DI6UZ±03

± DIAGNOSTICSENGINE
DI±103
2001 PRIUS (RM778U)
DTC P0450 Evaporative Emission Control System
Pressure Sensor Malfunction
DTC P0451 Evaporative Emission Control System
Pressure Sensor Range/Performance
CIRCUIT DESCRIPTION
The vapor pressure sensor, VSV for canister closed valve (CCV) and VSV for pressure switching valve are
used to detect abnormalities in the evaporative emission control system.
The ECM decides whether there is an abnormality in the evaporative emission control system based on the
vapor pressure sensor signal.
DTC P0450 or P0451 is recorded by the ECM when the vapor pressure sensor malfunction.
DTC No.DTC Detecting ConditionTrouble Area
P0450
10 seconds or less after engine starting condition (a) or (b)
continues for 7 seconds or more: (2 trip detection logic)
(a) Vapor pressure sensor value < ±4.0 kPa (±30 mmHg, ±1.2
in.Hg)
(b) Vapor pressure sensor value
2.0 kPa (15 mmHg, 0.6
in.Hg)

Open or short in vapor pressure sensor circuit

Vapor pressure sensor
ECM
P0451
Vapor pressure sensor output extremely changes under condi-
tion:
Vehicle speed: 0 km/h (0mph),Engine speed: Idling (2 trip
detection logic)
ECM
WIRING DIAGRAM
Refer to DTC P0440 on page DI±81.
INSPECTION PROCEDURE
HINT:

If DTC P0441, P0446, P0450 or P0451 is output after DTC P0440, first trouble shoot DTC P0441,
P0446 P0450 or P0451. If no malfunction is detected, troubleshoot DTC P0440 next.

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 was warmed up or not, the air±fuel
ratio was lean or rich, etc. at the time of the malfunction.

When the ENGINE RUN TIME in the freeze frame data is less than 200 seconds, carefully check the
VSV for EVAP, charcoal canister and vapor pressure sensor.
DI7SV±01

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

A14059
B±G
EFICIR OPN
Relay
MREL Engine Room J/B
1A
B
AECM
FC
F16
Fuel
Pump
IE 5
FL Block No. 1
MAIN
F12
BatteryE8
E9 259
W±B
J17
J/C J1
J/C
IG J7
J/C IA1
IA2
W±B
AA A W±B G±R B±R
F18
FL Block No. 2EFI
Relay
1K 1F
1B10
1F
2 121
3
2
1
3
3
1
11 52 1
3
F13G±R
B±R
7 14
4
G±R
± DIAGNOSTICSENGINE
DI±161
2001 PRIUS (RM778U)
Fuel Pump Control Circuit
CIRCUIT DESCRIPTION
When starting the engine with ignition switch:
HV ECU receives ST signal and decides to start the engine, and send the signal of the engine start prior
signal to the engine ECU by the communicatio between the engine ECU and HV ECU.
Engien ECU receives that signal and turns ON the circuit opening relay slightly earlier, then turns the fuel
pump.
When starting the engine in an intermittent operation:
With the cranking by MG1, NE signal comes in immediately, so the engine ECU receives the generation of
NE signal and turns the fuel pump. (At this time, no refernce of the communication from HV ECU)
When stopping the fuel pump:
When the signal to stop the engine comes in to the engine ECU from HV ECU from HV ECU side, the fuel
pump stops.
At the time of the fuel cut opetation such as deceleration by the engine brake, the fuel pump stops.
WIRING DIAGRAM
DI7T7±01

DI±194
± DIAGNOSTICSHYBRID VEHICLE CONTROL SYSTEM
2001 PRIUS (RM778U)
0: When engine is stopped
1: When stopping engine
2: When starting engine
DRIVE CONDITION3: When cranking engine or engine is operatingDRIVE CONDITION
4: While generating power or load driving
5: ±
6: While racing engine in P position
DRIVING PATTEN1History of driving pattern 1
DRIVING PATTEN2History of driving pattern 2
DRIVING PATTEN3History of driving pattern 3
DRIVING PATTERNHIstory of driving
ECU TYPEECU type
ENG INDPDET RQFactors causing engine to run independently
ENG STOP RQSTEngine stop request
ENG STP INHIBITEngine stop inhibition
ENG WARM UP RQTEngine warming up request
ENGINE FUEL CUTEngine fuel cut
ENGINE SPDEngine speed
EXCLUSIVE INFO1Exclusive information 1
EXCLUSIVE INFO2Exclusive information 2
EXCLUSIVE INFO3Exclusive information 3
EXCLUSIVE INFO4Exclusive information 4
EXCLUSIVE INFO5Exclusive information 5
EXCLUSIVE INFO6Exclusive information 6
FUEL SHORTAGELow fuel
HCAC ABSRT RQSTHCAC OBD request
HV BATT CH RQSTRequest from HV ECU to charge the battery
HV ECU INTERMITTENTHV ECU intermittent problems
IDLING REQUESTEngine idling request
IG OFF IN DRVINTurning IG OFF while driving the car
IG OFF TIMEIG OFF time
ILK OPERATIONInterlock operation
INFORMATION 1±5Information code
INPUT V LOWInput voltage is too low
INPUT V OVERInput voltage is too high
INTAKE AIRIntake air temperature
INVERT TEMP±MG1Temperature of inverter MG1
INVERT TEMP±MG2Temperature of inverter MG2
LATEST OPERLatest number of operation
LATEST TRIPLatest number of trips (IG ON±OFF)
LOAD CONDITIONIndicating which of MG1 or MG2 the vehicle uses more
MAIN BATT LOWSOC of main battery becomes low
MCYL CTRL POWERTorque for controlling oil pressure of master cylinder
MG1 TEMP HIGHTemperature MG1 is too high
MG2 TEMP HIGHTemperature MG2 is too high
MG1 CURRENT VElectric current of MG1 V phase

F12396
DLC3
TOYOTA hand±held tester
DI±318
± DIAGNOSTICSHV BATTERY CONTROL SYSTEM
2001 PRIUS (RM778U)
(d) Clear DTC after completion of repair.
(1) Connect the TOYOTA hand±held tester to the
DLC3.
HINT:
Before clearing, check that DTC for the HV battery ECU, DTC
for the ECU which is related with freeze frame data and the
freeze frame data are recorded.
(2) Operate the TOYOTA hand±held tester to erase the
DTC (See the TOYOTA hand±held tester opera-
tor 's manual.).
4. CHECK FOR INTERMITTENT PROBLEMS
(a) Perform a simulation test (See page IN±30).
HINT:
In the simulation test, reproduce the condition at trouble occurrence based on the customer's comments and
the freeze frame data recorded with the DTC.
(b) Check the connector and terminal (See page IN±41).
(c) Handle the connector (See page IN±41).
5. TOYOTA HAND±HELD TESTER DISPLAY ITEMS
TOYOTA hand±held tester displayMeasurement Item
BATTERY SOCBattery State of charge
ONB CHARGE TIMECumulative number of times of on±board equalizing charging
BATTERY LO TIMECumulative number of times of battery dies
DC INHIBIT TIMECumulative number of times of discharge inhibition
IB MAIN BATTERYIB main battery current (with correction)
BATT BLOCK V#Battery block voltage
BAT BLOCK MIN VBattery block minimum voltage
MIN BAT BLOCK #Minimum voltage battery block
BAT BLOCK MAX VBattery block maximum voltage
MAX BAT BLOCK #Maximum voltage battery block
BATT INSIDE AIRAmbient temperature inside battery pack
BATTERY TOO HI #Cumulative number of times of too±high battery voltage
VMF FAN VOLTAGEBattery cooling fan voltage
AUX. BATT VAuxiliary battery voltage
WINCharge restriction value
WOUTDischarge restriction value
DELTA SOCDifference between MAX. and MIN. values of SOC at every battery block.
SBLW FAN ST RQSSBL cooling fan stop request signal
COOLING FAN HICooling fan operation in high speed
COOLING FAN MIDCooling fan operation in middle speed
COOLING FAN LOCooling fan operation in low
CCTLOff±board equalizing charge control signal
EQC0 DF RELAYEQC0 dead front relay
EQTR CHARGE STEQTR uniform charging start signal
ONBORD CHARGEOn±board equalizing charging status
PRE ONBORDE CHPre±On±board charging status
NORMAL STATUSNormal status
INSIDE RESIST #Inside resistance