Page 1007 of 1897
A02397
OCV Signal Waveform
1 m sec./Division5 V/
Division
GND
(A) (A) (A)
DI-128
- DIAGNOSTICSENGINE
284 Author: Date:
2001 AVALON (RM808U)
TOYOTA hand-held tester:
1 Check valve timing (See page EM-15).
NG Repair valve timing.
OK
2 Check operation of OCV.
PREPARATION:
(a) Start the engine and warmed it up.
(b) Connect the TOYOTA hand-held tester and select the VVT from the ACTIVE TEST menu.
CHECK:
Check the engine speed when operate the OCV by the TOYOTA hand-held tester.
OK:
OCV is OFF: Normal engine speed
OCV is ON: Rough idle or engine stall
OK VVT system is OK.*
*: DTCs P1349 and P1354 are also output after the foreign ob-
ject is caught in some part of the system in the engine oil and
the system returns to normal in a short time. As ECM controls
so that foreign objects are ejected, there is no problem about
VVT. There is also no problem since the oil filter should get the
foreign object in the engine oil.
NG
3 Check voltage between terminals OCV+ and OCV- of ECM connector.
Reference: INSPECTION USING OSCILLOSCOPE
Turn the ignition switch ON, and check the waveform between
terminals OCV+ and OCV- of the ECM connector.
HINT:
The correct waveform is as shown.
The waveform frequency (A) is lengthened as the engine
speed becomes higher.
NG Check and replace ECM (See page IN-30).
Page 1010 of 1897
A06076
OCV Connector(a)
(b)
A02397
OCV Signal Waveform
1 msec./Division5 V/
Division
GND
(A) (A) (A)
- DIAGNOSTICSENGINE
DI-131
287 Author: Date:
2001 AVALON (RM808U)
2 Check operation of OCV.
PREPARATION:
Start the engine.
CHECK:
(a) Check the engine speed when disconnecting the OCV
connector.
(b) Check the engine speed when applying battery positive
voltage between the terminals of the OCV.
RESULT:
ResultCheck (a)Check (b)
1Normal engine speedRough idle or engine stall
2Except 1
2 Go to step 4.
1
3 Check voltage between terminals OCV+ and OCV- of ECM connector.
Reference: INSPECTION USING OSCILLOSCOPE
Turn the ignition switch ON, check the waveform between termi-
nals OCV+ and OCV- of the ECM connector.
HINT:
The correct waveform is as shown.
The waveform frequency (A) is lengthened as the engine
speed becomes higher.
OK VVT system is OK.*
*: DTCs P1349 and P1354 are also output after the foreign ob-
ject is caught in some part of the system in the engine oil and
the system returns to normal in a short time. As ECM controls
so that foreign objects are ejected, there is no problem about
VVT. There is also no problem since the oil filter should get the
foreign object in the engine oil.
NG
Page 1014 of 1897
A02037
ON
ON
STP
Brake Pedal
DepressedBrake Pedal
Released
(+)
(-)
- DIAGNOSTICSENGINE
DI-135
291 Author: Date:
2001 AVALON (RM808U)
OK
2 Check STP signal.
When using TOYOTA hand-held tester:
PREPARATION:
(a) Connect the TOYOTA hand-held tester to the DLC3.
(b) Turn the ignition switch ON and push the TOYOTA hand-
held tester main switch ON.
CHECK:
Read the STP signal on the TOYOTA hand-held tester.
OK:
Brake PedalSTP Signal
DepressedON
ReleasedOFF
When not using TOYOTA hand-held tester:
PREPARATION:
Turn the ignition switch ON.
CHECK:
Check the voltage between terminal STP of the ECM connector
and body ground.
OK:
Brake PedalVoltage
Depressed7.5 - 14 V
ReleasedBelow 1.5 V
OK Check for intermittent problems
(See page DI-3).
NG
3 Check harness and connector between ECM and stop light switch
(See page IN-30).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN-30).
Page 1015 of 1897
A11417
Battery FL
Main B
F6 F71 12
81
B Fusible
Link BlockEngine Room J/B
2G 2B E8B-RECM
BATT EFI No.1
II1 10
B-R DI-136
- DIAGNOSTICSENGINE
292 Author: Date:
2001 AVALON (RM808U)
DTC P1600 ECM BATT Malfunction
CIRCUIT DESCRIPTION
Battery positive voltage is supplied to terminal BATT of the ECM even when the ignition switch is OFF for
use by the DTC memory and air-fuel ratio adaptive control value memory, etc.
DTC No.DTC Detecting ConditionTrouble Area
P1600Open in back up power source circuitOpen in back up power source circuit
ECM
HINT:
If DTC P1600 appear, the ECM does not store another DTC.
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 was warmed up or not, the air-fuel ratio was lean
or rich, etc. at the time of the malfunction.
DI089-09
Page 1021 of 1897
- DIAGNOSTICSENGINE
DI-53
209 Author: Date:
DTC P0171 System too Lean (Fuel Trim)
DTC P0172 System too Rich (Fuel Trim)
DTC P0174 System too Lean (A/F Lean Malfunction,
Bank2)
DTC P0175 System too Rich (Bank2)
CIRCUIT DESCRIPTION
Fuel trim refers to the feedback compensation value compared to the basic injection time. Fuel trim includes
short-term fuel trim and long-term fuel trim.
Short-term fuel trim is the short-term fuel compensation used to maintain the air-fuel ratio at its ideal
theoretical value.
The signal from the A/F sensor is approximately proportional to the existing air-fuel ratio, and ECM compar-
ing it with the ideal theoretical value, the ECM reduces fuel volume immediately if the air-fuel ratio is rich
and increases fuel volume if it is lean.
Long-term fuel trim compensates the deviation from the central value of the short-term fuel trim stored up
by each engine tolerance, and the deviation from the central value due to the passage of time and changes
of using environment.
If both the short-term fuel trim and long-term fuel trim exceed a certain value, it is detected as a malfunction
and the MIL lights up.
DTC No.DTC Detecting ConditionTrouble Area
P0171
P0174When air-fuel ratio feedback is stable after engine warming up,
fuel trim is considerably in error on rich side (2 trip detection
logic)
Air induction system
Injector blockage
Mass air flow meter
Engine coolant temp. sensor
Fuel pressure
Gas leakage on exhaust system
Open or short in A/F sensor (bank 1, 2 sensor 1) circuit
A/F sensor (bank 1, 2 sensor 1)
ECM
P0172
P0175When air-fuel ratio feedback is stable after engine warming up,
fuel trim is considerably in error on lean side (2 trip detection
logic)
Injector leak, blockage
Mass air flow meter
Engine coolant temp. sensor
Ignition system
Fuel pressure
Gas leakage on exhaust system
Open or short in A/F sensor (bank 1, 2 sensor 1) circuit
A/F sensor (bank 1, 2 sensor 1)
ECM
DI6T4-03
Page 1023 of 1897
- DIAGNOSTICSENGINE
DI-55
211 Author: Date:
3 Check mass air flow meter (See page SF-31) and engine coolant temperature
sensor (See page SF-73).
NG Repair or replace.
OK
4 Check for spark and ignition (See page IG-1).
NG Repair or replace.
OK
5 Check fuel pressure (See page SF-6).
NG Check and repair fuel pump, pressure regulator,
fuel pipe line and filter.
OK
6 Check gas leakage on exhaust system.
NG Repair or replace.
OK
Page 1027 of 1897
A02045
START
STA
(+) (-)
- DIAGNOSTICSENGINE
DI-143
299 Author: Date:
2001 AVALON (RM808U)
TOYOTA hand-held tester:
1 Connect TOYOTA hand-held tester, and check STA signal.
PREPARATION:
(a) Connect the TOYOTA hand-held tester to the DLC3.
(b) Turn the ignition switch ON and push the TOYOTA hand-held tester main switch ON.
CHECK:
Read the STA signal on the TOYOTA hand-held tester while the starter operates.
OK:
Ignition Switch PositionONSTART
STA SignalOFFON
OK Proceed to next circuit inspection shown on
problem symptom table (See page DI-22).
NG
2 Check for open in harness and connector between ECM and starter relay (Mark-
ing: ST) (See page IN-30).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN-30).
OBD II scan tool (excluding TOYOTA hand-held tester):
1 Check voltage between terminal STA of ECM connector and body ground.
PREPARATION:
Remove the glove compartment (See page SF-83).
CHECK:
Measure the voltage between terminal STA of the ECM connec-
tor and body ground during the engine cranking.
OK:
Voltage: 6 V or more
OK Proceed to next circuit inspection shown on
problem symptom table (See page DI-22).
Page 1031 of 1897
- DIAGNOSTICSENGINE
DI-15
171 Author: Date:
P0171
(DI-53)System too Lean (Fuel Trim)
Air induction system
Injector blockage
Mass air flow meter
Engine coolant temp. sensor
Fuel pressure
Gas leakage on exhaust system
Open or short in A/F sensor (bank 1, 2 sensor 1) circuit
A/F sensor (bank 1, 2 sensor 1)
ECM
P0172
(DI-53)System too Rich (Fuel Trim)
Injector leak, blockage
Mass air flow meter
Engine coolant temp. sensor
Ignition system
Fuel pressure
Gas leakage on exhaust system
Open or short in A/F sensor (bank 1, 2 sensor 1) circuit
A/F sensor (bank 1, 2 sensor 1)
ECM
P0174
(DI-53)System too Lean
(A/F Lean Malfunction)Same as DTC P0171
P0175
(DI-53)System too Rich
(A/F Rich Malfunction)Same as DTC P0172
P0300
(DI-58)Random/Multiple Cylinder Misfire
Detected
P0301
(DI-58)Cylinder 1 Misfire DetectedOpen or short in engine wire
Connector connection
Vh tiP0302
(DI-58)Cylinder 2 Misfire Detected
Vacuum hose connection
Ignition system
Injector
P0303
(DI-58)Cylinder 3 Misfire Detected
Injector
Fuel pressure
Mass air flow meter
*2
P0304
(DI-58)Cylinder 4 Misfire Detected
Mass air flow meter
Engine coolant temp. sensor
Compression pressure
Vl lP0305
(DI-58)Cylinder 5 Misfire Detected
Valve clearance
Valve timing
ECM
P0306
(DI-58)Cylinder 6 Misfire Detected
ECM
P0325
(DI-64)Knock Sensor 1 Circuit Malfunc-
tion (Bank 1)Open or short in knock sensor 1 circuit
Knock sensor 1 (looseness)
ECM
P0330
(DI-64)Knock Sensor 2 Circuit Malfunc-
tion (Bank 2)Open or short in knock sensor 2 circuit
Knock sensor 2 (looseness)
ECM
P0335
(DI-67)Crankshaft Position Sensor ºAº
Circuit Malfunction
Open or short in crankshaft position sensor circuit
Crankshaft position sensor
Crankshaft timing pulley
ECM
P0340
(DI-69)Camshaft Position Sensor Circuit
Malfunction
Open or short in camshaft position sensor circuit
Camshaft position sensor
Camshaft timing gear
ECM
P0420
(DI-71)Catalyst System Efficiency Be-
low Threshold (Bank 1)
Gas leakage on exhaust system
A/F sensor (bank 1, 2 sensor 1)
Heated oxygen sensor (bank 1 sensor 2)
Three-way catalytic converter
