2001 TOYOTA AVALON Service Repair Manual

DI-66
- DIAGNOSTICSENGINE
222 Author
: Date
:
2001 AVALON (RM808U)
Type I
2 Check for open and short in harness and connector between EB1 connector and
ECM (See page IN-30).
NG Repair or replace harness or connector.
OK
Check and replace ECM (See page IN-30).
3 Check for open and short in harness and connector between EB1 connector and
knock sensor (See page IN-30).
HINT:

If DTC P0325 has changed to P0330, check the knock sensor circuit on the right bank side.

If DTC P0330 has changed to P0325, check the knock sensor circuit on the left bank side.
NG Repair or replace harness or connector.
OK
Replace knock sensor.

A11084
Right Bank VVT Sensor (Camshaft Position Sensor)
Crankshaft Position Sensor1
2
1
2
B-W B-W
L
L16
2410ECM
VV1+
NE+
NE-
E2
21LB-W
LE4
E5
VV2+ 22 Left Bank VVT Sensor (Camshaft Position Sensor)E5
E4 CC
C
CJ8 J/C
- DIAGNOSTICSENGINE
DI-67
223 Author
: Date
:
2001 AVALON (RM808U)
DTC P0335 Crankshaft Position Sensor ºAº Circuit Mal-
function
CIRCUIT DESCRIPTION
Crankshaft position sensor (NE signal) consists of a magnet, iron core and pickup coil.
The NE signal plate has 34 teeth and is installed the crankshaft timing pulley. The NE signal sensor gener-
ates 34 signals at every engine revolution. The ECM detects the standard crankshaft angle based on the
G (VV) signal, and the actual crankshaft angle and the engine speed by the NE signal.
DTC No.DTC Detecting ConditionTrouble Area
P0335
No crankshaft position sensor signal to ECM during cranking
(2 trip detection logic)
Open or short in crankshaft position sensor circuit

Crankshaft position sensor
P0335No crankshaft position sensor signal to ECM with engine
speed 600 rpm or more (2 trip detection logic)

Crankshaft osition sensor

Crankshaft timing pulley

ECM
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:

Perform troubleshooting of DTC P0335 first. If no trouble is found, troubleshoot the following mechani-
cal systems.

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.
DI07U-09

A11663
VV1, VV2 and NE Signal Waveforms2 V
/Division
20 msec./Division (Idling)
VV1
NE VV2GND
GND
GND
DI-68
- DIAGNOSTICSENGINE
224 Author
: Date
:
2001 AVALON (RM808U)
1 Check resistance of crankshaft position sensor (See page IG-9).
Reference: INSPECTION USING OSCILLOSCOPE
During cranking or idling, check the waveforms between termi-
nals VV1 and NE-, VV2 and NE-, and NE and NE- of the ECM
connectors.
HINT:
The correct waveforms are as shown.
NG Replace crankshaft position sensor.
OK
2 Check for open and short in harness and connector between ECM and crank-
shaft position sensor (See page IN-30).
NG Repair or replace harness or connector.
OK
3 Inspect sensor installation and signal plate teeth of crankshaft timing pulley.
NG Tighten sensor. Replace crankshaft timing
pulley.
OK
Check and replace ECM (See page IN-30).

- DIAGNOSTICSENGINE
DI-69
225 Author
: Date
:
2001 AVALON (RM808U)
DTC P0340 Camshaft Position Sensor Circuit Malfunc-
tion
CIRCUIT DESCRIPTION
Camshaft position sensor (G (VV) signal) consists of a magnet, iron core and pickup coil.
The G (VV) signal plate has 3 teeth, on its outer circumference and is installed the camshaft timing gear.
When the camshafts rotate, the protrusion on the signal plate and the air gap on the pickup coil change,
causing fluctuations in the magnetic field and generating an electromotive force in the pickup coil.
The NE signal plate has 34 teeth and is installed the crankshaft timing pulley. The NE signal sensor gener-
ates 34 signals at every engine revolution. The ECM detects the standard crankshaft angle based on the
G (VV) signal and the actual crankshaft angle and the engine speed by the NE signal.
DTC No.DTC Detecting ConditionTrouble Area
P0340
No camshaft position sensor signal to ECM during cranking (2
trip detection logic)
Open or short in camshaft position sensor circuit

Camshaft position sensor
P0340No camshaft position sensor signal to ECM with engine speed
600 rpm or more

Camshaft osition sensor

Camshaft timing gear

ECM
WIRING DIAGRAM
Refer to DTC P0335 on page DI-67.
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.
1 Check resistance of camshaft position sensor (See page IG-1).
Reference: INSPECTION USING OSCILLOSCOPE
Refer to DTC P0335 on page DI-67.
NG Replace camshaft position sensor.
OK
2 Check for open and short in harness and connector between ECM and camshaft
position sensor (See page IN-30).
NG Repair or replace harness or connector.
DI07V-09

DI-70
- DIAGNOSTICSENGINE
226 Author
: Date
:
2001 AVALON (RM808U)
OK
3 Inspect sensor installation and signal plate teeth of camshaft timing gear.
NG Tighten sensor. Replace camshaft timing gear.
OK
Check and replace ECM (See page IN-30).

A01674
Waveform of
A/F Sensor
Normal CatalystWaveform of Heated Oxygen
Sensor behind Catalyst
Abnormal Catalyst
- DIAGNOSTICSENGINE
DI-71
227 Author
: Date
:
2001 AVALON (RM808U)
DTC P0420 Catalyst System Efficiency Below Threshold
(Bank 1)
CIRCUIT DESCRIPTION
The ECM observes the waveform of the heated oxygen sensor located behind the catalyst to determine
whether the catalyst performance has deteriorated.
If the catalyst is functioning normally, the waveform of the heated oxygen sensor located behind the catalyst
switches back and forth between rich and lean much more slowly.
When the waveform of the heated oxygen sensor located behind the catalyst alternates flutteringly between
rich and lean, it indicates that catalyst performance has deteriorated.

DTC No.DTC Detecting ConditionTrouble Area
P0420
After engine and catalyst are warmed up, and while vehicle is
driven within set vehicle and engine speed range, waveform of
heated oxygen sensor (bank 1 sensor 2) alternates flutteringly
between rich and lean (2 trip detection logic)
Gas leakage on exhaust system

A/F sensor (bank 1, 2 sensor 1)

Heated oxygen sensor (bank 1 sensor 2)

Three-way catalytic converter
DI6T5-01

A00479
Engine Speed
3,000 rpm
Idling
IG SW OFF
Warmed up
3 min. or so
CheckTime (a)(c) (d)
(b) 2,000 rpm
2 sec. 2 sec.
DI-72
- DIAGNOSTICSENGINE
228 Author
: Date
:
2001 AVALON (RM808U)
CONFIRMATION ENGINE RACING PATTERN
(a) Connect the OBD II scan tool or TOYOTA hand-held tester to the DLC3.
(b) Start engine and warm it up with all the accessories switched OFF until the water temperature is stable.
(c) Race the engine at 2,500 - 3,000 rpm for about 3 min.
(d) When racing the engine at 3,000 rpm for 2 sec. and 2,000 rpm for 2 sec. alternately, check the wave-
form of the heated oxygen sensor (bank 1 sensor 2).
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.
1 Are there any other codes (besides DTC P0420) being output?
YES Go to relevant DTC chart (See page DI-14).
NO
2 Check gas leakage on exhaust system.
NG Repair or replace.
OK

- DIAGNOSTICSENGINE
DI-73
229 Author
: Date
:
2001 AVALON (RM808U)
3 Check A/F sensor (bank 1, 2 sensor 1) (See page SF-79).
NG Repair or replace.
OK
4 Check heated oxygen sensor (bank 1 sensor 2) (See page SF-81).
NG Repair or replace.
OK
Replace three-way catalytic converter (See
page EC-15).