2001 TOYOTA PRIUS Service Repair Manual

DI±62
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
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 Check air induction system (See page SF±1).
NG Repair or replace.
OK
2 Check injector injection (See page SF±12).
NG Replace injector.
OK
3 Check mass air flow meter and engine coolant temp. sensor
(See page SF±22 and SF±49).
NG Repair or replace.
OK
4 Check for spark and ignition (See page IG±1).
NG Repair or replace.
OK

P18349
± DIAGNOSTICSENGINE
DI±63
2001 PRIUS (RM778U)
5 Check fuel pressure (See page SF±6).
NG Check and repair fuel pump and fuel pipe line.
OK
6 Check gas leakade on exhaust system.
NG Repair or replace.
OK
7 Check the output voltage of heated oxygen sensor during idling.
PREPARATION:
Warm up the oxygen sensor the engine at 2,500 rpm for approx. 90 sec.
CHECK:
Use the OBD II scan tool or TOYOTA hand±held tester read the output voltage of the heated oxygen sensor
during idling.
OK:
Oxygen sensor output voltage:
Alternates repeatedly between less than 0.4 V and more than 0.55 V (See the following table).
OK Go to step 9.
NG

DI±64
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
8 Check for open and short in harness and connector between ECM and heated
oxygen sensor (See page IN±30).
NG Repair or replace harness or connector.
OK
Replace heated oxygen sensor.
9 Perform confirmation driving pattern (See page DI±50).
GO
10 Is there DTC P0171 being output again?
YES Check and replace ECM.
NO
11 Did vehicle runs out of fuel in the past?
NO Check for intermittent problems.
YES
DTC P0171 or P0172 is caused by running out
of fuel.

± DIAGNOSTICSENGINE
DI±65
2001 PRIUS (RM778U)
DTC P0300 Random/Multiple Cylinder Misfire Detected
DTC P0301 Cylinder 1 Misfire Detected
DTC P0302 Cylinder 2 Misfire Detected
DTC P0303 Cylinder 3 Misfire Detected
DTC P0304 Cylinder 4 Misfire Detected
CIRCUIT DESCRIPTION
Misfire: The ECM uses the crankshaft position sensor and camshaft position sensor to monitor changes in
the crankshaft rotation for each cylinder.
The ECM counts the number of times the engine speed change rate indicates that misfire has occurred. And
when the misfire rate equals or exceeds the count indicating that the engine condition has deteriorated, the
MIL lights up.
If the misfire rate is high enough and the driving conditions will cause catalyst overheating, the MIL blinks
when misfiring occurs.
DTC No.DTC Detecting ConditionTrouble Area
P0300Mi fi i f d li d i d t t d d i ti l

Open or short in engine wire

Connector connection

Vacuum hose connection

I
gnition systemP0300
P0301
P0302
P0303
P0304
Misfiring of random cylinders is detected during any particular
200 or 1,000 revolutions
For any particular 200 revolutions for the engine, misfiring is
detected which can cause catalyst overheating
(This causes MIL to blink)

Ignition system

Injector

Fuel pressure

Manifold absolute pressure sensor

En
gine coolant temp. sensorP0304(This causes MIL to blink)
Engine coolant tem. sensor

Compression pressure

Valve clearance

Valve timing

ECM
HINT:

When the 2 or more codes for a misfiring cylinder are recorded repeatedly but no random misfire code
is recorded, it indicates that the misfires were detected and recorded at different times.

There is a case where the cylinder other than memorized has an accidental fire (the cylinder which is
one ahead of fired cylinder), so. at the time of checking all the checking items and if there is no ab-
normality, check the cylinder which is different from the recorded cylinder as fired.
DI6V8±03

A14053
Battery F13 A
B 1K
1 AM2 Engine RoomJ/B
W±R
71 1A
1E5
6Instrument
Panel J/B65
B±R
IG2
B±GR±W
B±W B±W
B±W
B±WI5
Injector No. 1
1
2C1
21
2
1 2
J1
J/C
B±W
L±W
1 9
2G
2BE8
E8
E7
E7Engine ECU
#10
#20
#30
#40 Y
11 3
I15
Ignition SW W±B1J
12
F12 A
MAIN
I6
Injector No. 2
I7
Injector No. 3
I8
Injector No. 4
1J
1B
AM2
A3
2G2
2
2
J7
J/C
B±W
B±W
B±W
B±WB±W
W±R
IG2
Relay
2 2
1 3
5
1 W±BFL Block No. 1
F18 FL Block No. 2 DI±66
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
WIRING DIAGRAM
CONFIRMATION DRIVING PATTERN
(a) Connect the TOYOTA hand±held tester or OBD II scan tool.
(b) Record DTC and the freeze frame data.
(c) Use the TOYOTA hand±held tester to set to Check Mode. (See page DI±3)
(d) Drive the vehicle several times with the engine speed, load and its surrounding range shown with EN-
GINE SPD, CALC LOAD in the freeze frame data or MISFIRE RPM, MISFIRE LOAD in the data list.
If you have no TOYOTA hand±held tester, turn the ignition switch OFF after the symptom is simulated
the first time. Then repeat the simulation process again.
HINT:
In order to memorize DTC of misfire, it is necessary to drive around MISFIRE RPM, MISFIRE LOAD in the
data list for the following period of time.
Engine SpeedTime
1000 rpm3 minutes or more
2000 rpm1 minute 30 seconds or more
3000 rpm1 minute or more
(e) Check whether there is misfire or not by monitoring DTC and the freeze frame data. After that, record
them.