2001 TOYOTA PRIUS check engine

DI±168
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
5 Is any DTC output?
Check DTC on page DI±14.
YES Repair circuit indicated by output code.
NO
6 Check IG1 relay (Marking: IG1).
NG Replace IG1 relay.
OK
Check for short circuit in harness and con-
nector between DLC3 and ECM (See page
IN±41).

A14038
W±B 13TC E9
TC
CG D2 DLC3
4P±B
Instrument Panel J/B6 2
2K 2D ID1
AECM
ID W±BA J24
J/CE
W±BP±B
J11
J/C J26 J/C
P±B
A E
W±B 8 8P±BJ16 J/C
C
C
F08565
CG
(±)
(+) ON
TC
± DIAGNOSTICSENGINE
DI±169
2001 PRIUS (RM778U)
TC Terminal Circuit
CIRCUIT DESCRIPTION
Terminal TC and CG are located in the DLC3. When connecting these terminals, DTCs in normal mode or
test mode can be read through the MIL flashing in the combination meter.
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:

Even though terminal TC is not connected with terminal CG, the MIL blinks.

For the above phenomenon,an open or short in the wire harness, or malfunction inside the ECM is the
likely cause.
1 Check voltage between terminals TC and CG of DLC3.
PREPARATION:
Turn the ignition switch ON.
CHECK:
Measure the voltage between terminals TC and CG of the
DLC3.
OK:
Voltage: 9 ± 14 V
OK Check and replace ECM (See page IN±41).
NG
DI7DL±02

DI±170
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
2 Check continuity between terminal CG of DLC3 and body ground.
NG Repair or replace harness or connector.
OK
3 Check for open and short circuit in harness and connector between ECM and
DLC3, and DLC3 and body ground (See page IN±41).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN±41).

FI7012A11860
P±G A/C Control Assembly
A8 E10522
ACTECM
± DIAGNOSTICSENGINE
DI±171
2001 PRIUS (RM778U)
A/C Cut Control Circuit
CIRCUIT DESCRIPTION
This circuit cuts air conditioning operation during vehicle acceleration in order to increase acceleration per-
formance. During acceleration with the vehicle speed at (AT: 25 km/h (16 mph), MT: 40 km/h (25 mph)) or
less, engine speed at (AT: 1,200 rpm, MT:1,600 rpm) or less and throttle valve opening angle at 60° or more,
the A/C magnet switch is turned OFF for several seconds.
WIRING DIAGRAM
INSPECTION PROCEDURE
TOYOTA hand±held tester:
1 Connect the TOYOTA hand±held tester and check operation of air conditioning
cut control.
PREPARATION:
(a) Connect the TOYOTA hand±held tester to the DLC3.
(b) Turn the ignition switch ON and TOYOTA hand±held tester main switch ON.
(c) Start the engine and air conditioning switch ON.
HINT:
A/C magnet clutch is turned ON.
(d) Select the ACTIVE TEST mode on the TOYOTA hand±held tester.
CHECK:
Check operation of A/C magnet clutch cut when air conditioning cut control is operated by the TOYOTA
hand±held tester.
OK:
A/C magnet clutch is turned OFF.
DI7T8±01

A14008
START
(±)
(+)ACT
DI±172
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
OK Proceed to next circuit inspection shown on
problem symptom table. (See page DI±22)
NG
2 Check for open and short in harness and connector between ECM and A/C am-
plifier. (See page IN±41)
NG Repair or replace harness or connector.
OK
3 Check voltage between terminal ACT 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 ACT of ECM connector and
body ground when A/C switch is turned to ON and OFF.
OK:
A/C switch conditionVoltage
ON9 ± 14 V
OFFBelow 1.5 V
NG Check and replace A/C amplifier.
OK
Check and replace ECM. (See page IN±41)

A14008
START
(±)
(+)ACT
± DIAGNOSTICSENGINE
DI±173
2001 PRIUS (RM778U)
OBDII scan tool (excluding TOYOTA hand±held tester):
1 Check voltage between terminal ACT of ECM and body ground.
PREPARATION:
Start the engine.
CHECK:
Measure voltage between terminal ACT of ECM connector and
body ground when A/C switch is turned to ON and OFF.
OK:
A/C switch conditionVoltage
ON9 ± 14 V
OFFBelow 1.5 V
OK Check and repair ECM. (See page IN±41)
NG
2 Check for open and short in harness and connector between ECM and A/C am-
plifier. (See page IN±41)
NG Repair or replace harness or connector.
OK
Check and replace A/C amplifier.

DI82J±02
Prius Problem Check Sheet
Vehicle
Specifications
Please fill in the blanks within bold frame.Name of DealerPerson in Charge at
HeadquartersPerson in Charge
at Dealer
Model CodeOffice
Vehicle Delivery Date
Frame No.
Unit No. etc.
Option . . . :
( ) Navigation (equipped by ( ) MOP ( ) dealer) ( ) Cold climate specification
( ) others( )Problem Occurrence Date
Service Entry Date NHW11±
. .
. .Registration datemiles
. .
Contents of complaint (Status when and before/after occurring in
the order of events as correct as possible)Characteristics of Customer
Gender
Age
Occupation
Vehicle used before
Main use area
Frequency in use
Others times/day or
week or month
Status of engineOthers
Interview Results
( ) Male ( ) Female
suburbs ( ) %
Others ( ) ( ) %
city area ( ) %
mountain area ( ) %
Driving ConditionRoad Condition
Vehicle Condition
Vehicle Speed
km/h
( ) when starting
( ) when according
( ) When
normal driving
( ) when
decelerating
( ) when braking
( ) when shopping
( ) when parking
( ) when turning
( ) when
ABS actuating
( ) others
( )( ) flat road
( ) up hill ( ) down
hill incline of
° /%
distance
km
( ) dry paved road
( ) wet paved road
( ) rough paved road
( ) unpaved road
( ) snowy/frozen
road
( ) bump/curb
( ) others
( )( ) when starting
( ) right after
starting
( ) until min.
after starting
( ) until min.
after starting
of driving
( ) when shopping
system
( ) while shopping
engine
( ) when starting
engine
( ) when revolving
engineHV Battery
indication
( ) 4/4 ( ) 3/4
( ) 2/4 ( ) 1/4
( ) unidentified
Shift position
(indication)
( ) P ( ) R ( ) N
( ) D ( ) B
( ) when operating
"Weather:
A/C status
( ) no indication
( ) unidentified
( ) A/C ( ) FULL
( ) OFF
( ) unidentifiedWarning light
(MIL)
( ) ON ( ) OFF
( ) PS
( ) main battery
( ) HV!
( ) engine
( ) charge
( ) output
control
( ) brake
( ) ABS
( ) others
( )
Temperature:
°C
Brake operation
( ) brake slowly
( ) Brake suddenly
( ) use two pedals
system
Frequency in
occurrence
( ) always
( ) sometimes
( ) only once
Fuel level
( ) segmentsmphOdometer Reading
mph
°F km
± DIAGNOSTICSHYBRID VEHICLE CONTROL SYSTEM
DI±175
2001 PRIUS (RM778U)
CUSTOMER PROBLEM ANALYSIS CHECK

± DIAGNOSTICSHYBRID VEHICLE CONTROL SYSTEM
DI±193
2001 PRIUS (RM778U)
5. CHECK FOR INTERMITTENT PROBLEMS
(a) Perform a simulation test (See page IN±41).
In the simulation test, reproduce the driving condition at the trouble occurrence according to the cus-
tomer 's comments and freeze frame data recorded with DTC, such as an opening angle of the acceler-
ator pedal, SOC, engine coolant temperature, engine rpm, and MG/1MG2 rpm and torque.
(b) Check the connector and terminal (See page IN±41).
(c) Handle the connector (See page IN±41).
6. TOYOTA HAND±HELD TESTER DISPLAY ITEMS
TOYOTA Hand±held tester displayMeasurement Item
1 BEF LATST ORNumber of operation of 1 trip before last
1 BEF LATST TRPNumber of trips before last
2 BEF LATST ORNumber of operation 2 trips before last
2 BEF LATST TRPNumber of trips 2 before last
ABNML CON BR±HVCommunication malfunction between HV ECU and brake
ACC SENSOR MAINMain accelerator sensor
ACC SENSOR SUBSub accelerator sensor
ACC TENT TRBLETentative trouble of accelerator
ACC THROTTLEAccelerator throttle
ACCEL MODEHistory of acceleration and reduction
AIR CON REQUESTAir conditioner request
AUX. BATT LOWAuxiliary battery becomes week
AUX. BATT VVoltage of auxiliary battery
BATT HIGH TEMPTemperature of the battery is too high
BATT HIGH VOLTVoltage of the battery is too high
BATT LOW BOLTVoltage of the battery is low
BATT OVER LOADBattery is overloaded
BATT SAVE RQSTRequest to save the main battery
BATTERY FULLBattery full
BRAKE TORQBrake torque
CELL TEMP±MAXHighest temperature of all battery cells
CELL TEMP±MINLowest temperature of all battery cells
CHG RESTRICTIONCharge restriction
COOLANT TEMPWater temperature
CRUISE CONTROLCondition of the cruise control
DC/DC CONV STOPDC/DC converter stop signal
DC/DC CONV STOPFactors causing DC/DC converter to stop
DC/DC STOP FACTDC/DC converter has stopped at least once
DC/DC V UNSETDC/DC voltage is unsettled
DCHG RQST SOCDischarge request to adjust SOC
DISCHAG INHIBITBattery is inhibited to discharge