TOYOTA PRIUS 2001 Service Repair Manual

DI00H±16
FI0534
I12054
TOYOTA Hand±Held tester
DLC3
± DIAGNOSTICSENGINE
DI±3
2001 PRIUS (RM778U)
PRE±CHECK
1. DIAGNOSIS SYSTEM
(a) Description

When troubleshooting OBDII vehicles, the only dif-
ference from the usual troubleshooting procedure
is that you connect to the vehicle the OBDII scan
tool complying with SAE J1978 or TOYOTA hand±
held tester, and read off various data output from
the vehicle's ECM.

OBDII regulations require that the vehicle's on±
board computer lights up the Malfunction Indicator
Lamp (MIL) on the instrument panel when the com-
puter detects a malfunction in the emission control
system/components or in the powertrain control
components which affect vehicle emissions, or a
malfunction in the computer. In addition to the MIL
lighting up when a malfunction is detected, the ap-
plicable Diagnostic Trouble Code (DTC) prescribed
by SAE J2012 are recorded in the ECM memory
(See page DI±14).
If the malfunction does not reoccur in 3 consecutive trips, the
MIL goes off automatically but the DTCs remain recorded in the
ECM memory.

When DTC P3190, P3191 are detected and the re-
main of the fuel is little, the computer judges the
cause as a fuel shortage, and after the next trip,
when the supply of fuel is confirmed, it turns off MIL,
but the memory of DTC still remains.

To check the DTCs, connect the TOYOTA hand±
held tester or OBDII scan tool to Data Link Connec-
tor 3 (DLC3) on the vehicle. The TOYOTA hand±
held tester or OBDII scan tool also enables you to
erase the DTCs and check freezed frame data and
various forms of engine data. (For operating instruc-
tions, see the OBDII scan tool's instruction book.)

DTCs include SAE controlled codes and manufac-
turer controlled codes. SAE controlled codes must
be set as prescribed by the SAE, while manufactur-
er controlled codes can be set freely by the
manufacturer within the prescribed limits (See DTC
chart on page DI±14).

DI±4
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)

The diagnosis system operates in normal mode
during normal vehicle use. It also has a check mode
for technicians to simulate malfunction symptoms
and troubleshoot. Most DTCs use 2 trip detection
logic* to prevent erroneous detection, and ensure
thorough malfunction detection. By switching the
ECM to check mode when troubleshooting, the
technician can cause the MIL to light up for a mal-
function that is only detected once or momentarily
(TOYOTA hand±held tester only). (See step 2)

*2 trip detection logic:
When a malfunction is first detected, the malfunc-
tion is temporarily stored in the ECM memory (1st
trip).
If the same malfunction is first detected again during the second
drive test, this second detection causes the MIL to light up (2nd
trip). (However, the IG switch must be turned OFF between the
1st trip and the 2nd trip.)

Freeze frame data:
Freeze frame data records the engine condition
when a misfire (DTC P0300 ± P0304) or fuel trim
malfunction (DTC P0171, P0172) or other malfunc-
tion (first malfunction only), is detected.

Because freeze frame data records the engine
conditions (fuel system, calculated load, engine
coolant temperature, fuel trim,engine speed, ve-
hicle speed, etc.) when the malfunction is detected,
when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the en-
gine warmed up or not, the air±fuel ratio lean or rich,
etc. at the time of the malfunction.
Priorities for troubleshooting:
If troubleshooting priorities for multiple DTCs are given in the
applicable DTC chart, these should be followed.
If no instructions are given troubleshoot DTCs according to the
following priorities.
(1) DTCs other than fuel trim malfunction (DTC P0171,
P0172), and misfire (DTC P0300 ± P0304).
(2) Fuel trim malfunction (DTC P0171, P0172).
(3) Misfire (DTC P0300 ± P0304).

N09214
FI2547
± DIAGNOSTICSENGINE
DI±5
2001 PRIUS (RM778U)
(b) Check the DLC3.
The vehicle's ECM uses ISO 9141±2 for communication.
The terminal arrangement of DLC3 complies with SAE
J1962 and matches the ISO 9141±2 format.
Terminal No.Connection / Voltage or ResistanceCondition
7Bus  Line / Pulse generationDuring transmission
4Chassis Ground / e Body Ground 1 W or lessAlways
5Signal Ground / e Body Ground 1 W or lessAlways
16Battery Positive / e Body Ground 9 ± 14 VAlways
HINT:
If your display shows ºUNABLE TO CONNECT TO VEHICLEº
when you have connected the cable of the TOYOTA hand±held
tester or OBDII scan tool to DLC3, turned the ignition switch ON
and operated the scan tool, there is a problem on the vehicle
side or tool side.

If communication is normal when the tool is connected to
another vehicle, inspect DLC3 on the original vehicle.

If communication is still not possible when the tool is con-
nected to another vehicle, the problem is probably in the
tool itself, so consult the Service Department listed in the
tool's instruction manual.
2. INSPECT DIAGNOSIS (Normal Mode)
(a) Check the MIL
(1) The MIL comes on when the ignition switch is turned
ON and the engine is not running.
HINT:
If the MIL does not light up, troubleshoot the combination meter
(See page BE±42).
(2) When the engine started, the MIL should go off. If
the lamp remains on, the diagnosis system has de-
tected a malfunction or abnormality in the system.
(b) Check the DTC.
NOTICE:

If there is no DTC in the normal mode, check the 1st
trip DTC using Continuous Test Result function
(Mode 7 for SAE J1979) or the TOYOTA hand±held
tester or OBDII scan tool.

DI±6
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)

TOYOTA hand±held tester only:
When the diagnosis system is switched from normal
mode to check mode, it erases all DTCs and freezed
frame data recorded in normal mode. So before
switching modes, always check the DTCs and
freezed frame data, and note them down.
(1) Prepare the TOYOTA hand±held tester or OBDII
scan tool (complying with SAE J1978).
(2) Connect the TOYOTA hand±held tester or OBDII
scan tool to DLC3 under the instrument panel lower
pad.
(3) Turn the ignition switch ON and turn the TOYOTA
hand±held tester or OBDII scan tool switch ON.
(4) Use the TOYOTA hand±held tester or OBDII scan
tool to check the DTCs and freezed frame data;
note them down. (For operating instructions, see
the OBDII scan tool's instruction book.)
(5) See step 4 to confirm the details of the DTCs.
NOTICE:

When simulating symptoms with an OBDII scan tool
(excluding TOYOTA hand±held tester) to check the
DTCs, use normal mode. For code on the DTC chart
subject to º2 trip detection logicº, perform the follow-
ing either action.

Turn the ignition switch OFF after the symptom is
simulated the first time. Then repeat the simulation
process again. When the problem has been simulated
twice, the MIL lights up and the DTCs are recorded in
the ECM.

Check the 1st trip DTC using Mode 7 (Continuous Test
Results) for SAE J1979.
(c) Clear the DTC.
The DTCs and freezed frame data will be erased by either
action.
(1) Operating the TOYOTA hand±held tester or OBDII
scan tool (complying with SAE J1978) to erase the
codes. (See the OBDII scan tool's instruction book
for operating instructions.)
(2) Disconnecting the battery terminals or EFI fuse.
NOTICE:
If the TOYOTA hand±held tester switches the ECM from the
normal mode to the check mode or vice±versa, or if the
ignition switch is turned from ON to ACC or OFF during
check mode, the DTCs and freezed frame data will be
erased.

FI3605
ON
OFFFlashing
0.13 Second
± DIAGNOSTICSENGINE
DI±7
2001 PRIUS (RM778U)
3. INSPECT DIAGNOSIS (Check Mode)
TOYOTA hand±held tester only:
Compared to the normal mode, the check mode has an in-
creased sensitivity to detect malfunctions.
Furthermore, the same diagnostic items which are detected in
the normal mode can also be detected in the check mode.
(a) Check the DTC
(1) Initial conditions:

Battery positive voltage 11 V or more.

Throttle valve fully closed.

Transmission in ºPº or ºNº position.

A/C switched OFF.
(2) Turn the ignition switch OFF.
(3) Prepare the TOYOTA hand±held tester.
(4) Connect the TOYOTA hand±held tester to DLC3
under the instrument panel lower pad.
(5) Turn the ignition switch ON and switch the TOYOTA
hand±held tester ON.
(6) Switch the TOYOTA hand±held tester normal mode
to check mode. (Check that the MIL flashes.)
NOTICE:
If the TOYOTA hand±held tester switches the ECM from the
normal mode to the check mode or vice±versa, or if the
ignition switch is turned from ON to ACC or LOCK during
check mode, the DTCs and freezed frame data will be
erased.
(7) Switch the engine. (The MIL goes out after the en-
gine start.)
(8) Simulate the conditions of the malfunction de-
scribed by the customer.
NOTICE:
Leave the ignition switch ON until you have checked the
DTC, etc.
(9) After simulating the malfunction conditions, use the
TOYOTA hand±held tester diagnosis selector to
check the DTCs and freezed frame data, etc.
HINT:
Take care not to turn the ignition switch OFF. Turning the ignition
switch OFF switches the diagnosis system from check mode to
normal mode. so all DTCs, etc. are erased.
(10) After checking the DTC, inspect the applicable cir-
cuit.

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

EM9891
± DIAGNOSTICSENGINE
DI±9
2001 PRIUS (RM778U)
3 Check air filter.
PREPARATION:
Remove the air filter.
CHECK:
Visual check that the air filter is not dirty or excessive oily.
HINT:
If necessary, clean the air filter with compressed air. First blow
from inside thoroughly, then blow from outside of the air filter.
NG Repair or replace.
OK
4 Check engine idle speed.
PREPARATION:
(a) Warm up engine to normal operating temperature.
(b) Switch off all accessories.
(c) Switch off A/C.
(d) Shift transmission into P position.
(e) Connect the TOYOTA hand±held tester or OBDII scan tool to DLC3 on the vehicle.
(f) Transit to inspection mode.
CHECK:
Use CURRENT DATA to check the idle speed.
OK:
Idle speed: 950 ± 1,050 rpm
NG Proceed to problem symptoms table on page
DI±22.
OK

A04438A13924A14466
TC
CG
A14060
DI±10
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
5 Check ignition timing.
PREPARATION:
(a) Warm up engine to normal operating temperature.
(b) Shift transmission into P position.
(c) Keep the engine speed at idle.
(d) Using SST, connect terminals TE1 and E1 of DLC1.
SST 09843±18020
(e) Using a timing light, connect the tester to the ignition coil
connector wire (See page EM±11).
(f) Transit to inspection mode.
CHECK:
Check ignition timing.
OK:
Ignition timing: 7 ± 15° BTDC at idle
NG Proceed to page IG±1 and continue to trouble-
shoot.
OK
Proceed to problem symptoms table on page
DI±22.
6 Check fuel pressure.
PREPARATION:
(a) Be sure that enough fuel is in the tank.
(b) Connect the TOYOTA hand±held tester to the DLC3.
(c) Turn the ignition switch ON and push the TOYOTA hand±
held tester main switch ON.
(d) Use the ACTIVE TEST mode to operate the fuel pump.
(e) Please refer to the TOYOTA hand±held tester operator's
manual for further details.
(f) If you have no TOYOTA hand±held tester, connect the
positive (+) and negative (±) leads from the battery to the
fuel pump connector (See page SF±6).
CHECK:
Check for fuel pressure in the fuel inlet hose when it is pinched
off.
HINT:
At this time, you will hear a fuel flowing noise.

± DIAGNOSTICSENGINE
DI±11
2001 PRIUS (RM778U)
NG Proceed to page SF±6 and continue to trouble-
shoot.
OK
7 Check for spark.
PREPARATION:
(a) Remove the ignition coil (See page IG±5).
(b) Remove the spark plug.
(c) Install the spark plug to ignition coil and connect the ignition coil connector to ignition coil.
(d) Disconnect the injector connector.
(e) Be sure to ground the screw of the spark plug securely.
CHECK:
Check if spark occurs while engine is being cranked.
NOTICE:

Do not crash the electrode gap.

To prevent excess fuel being injected from the injectors during this test, don't crank the engine
for more than 5 ± 10 seconds at a time.
NG Proceed to page IG±1 and continue to trouble-
shoot.
OK
Proceed to problem symptoms table on page
DI±22.

DI±12
± DIAGNOSTICSENGINE
2001 PRIUS (RM778U)
7. ENGINE OPERATING CONDITION
NOTICE:
The values given below for ºNormal Conditionº are representative values, so a vehicle may still be
normal even if its value varies from those listed here. So do not decide whether a part is faulty or
not solely according to the ºNormal Conditionº here.
(a) CARB mandated signals.
TOYOTA hand±held tester displayMeasurement ItemNormal Condition*
FUEL SYS #1
Fuel System Bank 1
OPEN: Air±fuel ratio feedback stopped
CLOSED: Air±fuel ratio feedback operating
Idling after warming up: CLOSED
CALC LOAD
Calculator Load:
Current intake air volume as a proportion of max.
intake air volumeIdling: 5.4 ± 19.2 %
Racing without load (2,250rpm): 6.9 ± 16.2 %
COOLANT TEMP.Engine Coolant Temp. Sensor ValueAfter warming up: 80 ± 95°C (176 ± 203°F)
SHORT FT #1Short±term Fuel Trim Bank 10 ± 20%
LONG FT #1Long±term Fuel Trim Bank 10 ± 20%
ENGINE SPDEngine SpeedIdling: 1,000 rpm
VEHICLE SPDVehicle SpeedVehicle Stopped: 0 km/h (0 mph)
IGN ADVANCEIgnition Advance:
Ignition Timing of Cylinder No. 1Idling: BTDC 7 ± 15°
INTAKE AIRIntake Air Temp. Sensor ValueEquivalent to Ambient Temp.
MAF/AFMAir Flow Rate Through Mass Flow Meter
Idling: 1.11 ± 4.38 gm/sec.
Racing without load (2,250 rpm):
3.38 ± 7.88 gm/sec.
THROTTLE POS
Voltage Output of Throttle Position Sensor
Calculated as a percentage:
0 V "0%, 5 V "100%Throttle Fully Closed: 0 ± 5 %
Throttle Fully Open: 90 ± 100 %
O2S B1, S1Voltage Output of Heated Oxygen Sensor Bank
1, Sensor 1Idling: 0.1 ± 0.9 V
O2FT B1, S1Heated Oxygen Sensor Fuel Trim Bank 1, Sen-
sor 1 (Same as SHORT FT #1)0 ± 20 %
O2S B1, S2Voltage Output of Heated Oxygen Sensor Bank
1, Sensor 2Driving at 50 km/h (31 mph): 0.1 ± 0.9 V
*: If no conditions are specifically stated for ºldlingº, it means the shift lever is at P position, the A/C switch
is OFF and all accessory switches are OFF.
(b) TOYOTA Enhanced Signals.
TOYOTA hand±held tester displayMeasurement ItemNormal Condition*
MISFIRE RPMEngine RPM for first misfire rangeMisfire 0: 0 rpm
MISFIRE LOADEngine load for first misfire rangeMisfire 0: 0 g/r
INJECTORFuel injection time for cylinder No.1Idling: 1.0 ± 3.0 ms
CYL#1, CYL#2, CYL#3, CYL#4Abnormal revolution variation for each cylinder0 %
IGNITIONTotal number of ignition for every 1,000 revolu-
tions0 ± 2,000
FUEL PUMPFuel Pump SignalIdling: ON
EVAP (PURGE) VSVEVAP VSV SignalVSV operating: ON
VAPOR PRESS VSVVapor Pressure VSV SignalVSV operating: ON
TOTAL FT B1Total Fuel Trim Bank 1: Average value for fuel
trim system of bank 1Idling: 0.8 ± 1.2 V