TOYOTA RAV4 1996 Service Repair Manual

− DIAGNOSTICSENGINE
DI−71
1996 RAV4 (RM447U)
DTC P0402 Exhaust Gas Recirculation Flow Excessive
Detected
CIRCUIT DESCRIPTION
Refer to Exhaust Gas Recirculation Flow Insufficient Detected on page DI−65.
DTC No.DTC Detecting ConditionTrouble Area
P0402
After the engine is warmed up, conditions (a) and (b) continue
(a) The intake manifold absolute pressure is larger than the
value calculated by the ECM while the EGR system is ON.
(b) Misfiring is detected during idling
(2 trip detection logic)EGR valve stuck open
Vacuum or EGR hose is connected to wrong post
Manifold absolute pressure sensor
ECM
See DTC P0140 for System Check Driving Pattern and Wiring Diagram.
INSPECTION PROCEDURE
HINT:
If DTC ”P0105” and / or ”P0106” and ”P0402” are output simultaneously, perform troubleshooting of
DTC ”P0105” first.
If DTC ”P0401” and ”P0402” are output simultaneously, perform troubleshooting of DTC ”P0402” first.
1 Check the connection of the vacuum hose, EGR hose (See page EC−5).
NG Repair or replace.
OK
2 Check EGR valve (See page EC−8).
NG Repair or replace.
OK
3 Check the VSV for EGR * .
* If you have TOYOTA hand−held tester, see page DI−65, step 2.
If you have no TOYOTA hand−held tester, see page DI−65, step 2.
OK Go to step 5.
NG
DI3ZU−01

DI−72
− DIAGNOSTICSENGINE
1996 RAV4 (RM447U)
4 Check operation of the VSV for EGR (See page SF−43).
NG Replace VSV for EGR.
OK
Check for open and short in harness and con-
nector between R/B No.6 and ECM
(See page IN−30).
5 Check EGR vacuum modulator (See page EC−8).
NG Repair or replace.
OK
6 Check manifold absolute pressure sensor (See page DI−21).
NG Repair or replace.
OK
Check and replace ECM
(See page IN−30).

FI7081
Waveform of oxygen sensor
before catalystNormal
catalystWaveform of oxygen sensor
after catalyst
− DIAGNOSTICSENGINE
DI−73
1996 RAV4 (RM447U)
DTC P0420 Catalyst System Efficiency Below Threshold
CIRCUIT DESCRIPTION
The ECM compares the waveform of the oxygen sensor located before the catalyst with the waveform of
the oxygen sensor located after the catalyst to determine whether or not catalyst performance has deterio-
rated.
Air−fuel ratio feedback compensation keeps the waveform of the oxygen sensor before the catalyst repeat-
edly changing back and forth from rich to lean.
If the catalyst is functioning normally, the waveform of the oxygen sensor after the catalyst switches back
and forth between rich and lean much more slowly than the waveform of the oxygen sensor before the cata-
lyst.
But when both wavaforms change at a similar rate, it indicates that catalyst performance has deteriorated.
DTC NoDTC Detecting ConditionTrouble Area
P0420
After the engine and the catalyst are warmed up, and while the
vehicle is driven within the set vehicle and engine speed range,
the waveforms of the oxygen sensors (bank 1 sensor 1 and
bank 1 sensor 2) have the same amplitude
(2 trip detection logic)
Front TWC (front catalyst) and TWC w/pipe (rear catalyst)
Oxygen sensor
DI3ZV−01

(4) (3)
(2)
(1)
FI7132
2500 − 3000 rpm Engine Speed
Warmed up 3 minutes IG SW OFFIdling
Time
Check
FI6514
OX Signal Waveform (Oscilloscope)
200 msec./Division 1.0 V
0 V DI−74
− DIAGNOSTICSENGINE
1996 RAV4 (RM447U)
CONFIRMATION ENGINE RACING PATTERN
(1) Connect the TOYOTA hand−held tester to the DLC3, or connect the probe of the oscilloscope between
terminals OX1, OX2 and E1 of ECM.
(2) Start engine and warm it up with all accessories switched OFF until water temperature is stable.
(3) Race the engine at 2500 − 3000 rpm for about 3 min.
(4) After confirming that the waveforms of the oxygen sensor, bank 1 sensor 1 (OX1), oscillate around 0.5
V during feedback to the ECM, check the waveform of the oxygen senor, bank 1 sensor 2 (OX2).
HINT:
If there is a malfunction in the system, the waveform of the oxy-
gen senor, bank1 sensor 2 (OX2), is almost the same as that
of the oxygen sensors, bank 1 senor 1 (OX1), on the left.
There are some cases where, even though a malfunction ex-
ists, the MIL may either light up or not light up.

− DIAGNOSTICSENGINE
DI−75
1996 RAV4 (RM447U)
INSPECTION PROCEDURE
1 Are there any other codes (besides DTC P0420) being output?
YES Go to relevant DTC chart.
NO
2 Check oxygen senor (bank 1 sensor 1) (See page DI−42).
NG Repair or replace.
OK
3 Check oxygen senor (bank 1 sensor 2) (See page DI−45).
NG Repair or replace.
OK
Replace both of front TWC (front catalyst)
and TWC w/ pipe (rear catalyst) (See page
EC−11).

(2) (1)
(5)
S00043
ECM
VSV
for EVAP
Fuel Tank
Charcoal CanisterVSV for Vapor
Pressure SensorVapor Pressure
Sensor
(4)
(3) DI−76
− DIAGNOSTICSENGINE
1996 RAV4 (RM447U)
DTC P0440 Evaporative Emission Control System
Malfunction
CIRCUIT DESCRIPTION
The vapor pressure sensor and VSV for vapor pressure sensor are used to detect abnormalities in the evap-
orative emission control system.
The ECM decides whether there is an abnormality in the evaporative emission control system based on the
vapor pressure sensor signal.
DTC P0440 is recorded by the ECM when evaporative emissions leak from the components within the dotted
line in fig. 1 below, or when the vapor pressure sensor malfunctions.
DTC No.DTC Detecting ConditionTrouble Area
P0440
The fuel tank pressure is atmospheric pressure after the ve-
hicle is driven for 20 min.
(2 trip detection logic)
Vapor pressure sensor
Fuel tank cap incorrectly installed
Fuel tank cap cracked or damaged
Vacuum hose cracked, holed, blocked, damaged or discon-
nected ( (1) or (2) in fig. 1 ) ( (3) in fig. 1 )
Fuel tank cranked, holed or damaged
Charcoal canister cracked, holed or damaged
DI3ZW−01

S02388
6
66
6 3
15
2
1J 1E21J/B No.1 From
BatteryVaper Pressure Sensor
E5
E5
E5
E4
E58 229
7 1
EA1
B−R
B−O
11Fuse Block
From
IG SwitchVSV
(for Vapor
Pressure Sensor) VSV
(for EVAP)VC
PTNK
E2
EVP
TPCE01
E01 5V ECM
E1
B−R
1P
2 1
B−R BRL−Y Y
1 2 3
R/B No.6
2
B−R
W−B2
EA 10
IGN R−W
EFI Main Relay
R−W A
A
W−B
J1 Junction
Connector B−O
− DIAGNOSTICSENGINE
DI−77
1996 RAV4 (RM447U)
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
If DTC P0441, P0446 or P0450 is output after DTC P0440, first troubleshoot DTC P0441, P0446 or
P0450. If no malfunction is detected, troubleshoot DTC P0440 next.
Ask the customer whether, after the MIL came on, the customer found the fuel tank cap loose and tight-
ened it. Also ask the customer whether the fuel tank cap was loose when refuelling.
If the fuel tank cap was loose, it was the cause of the DTC. If the fuel tank cap was not loose or if the
customer was not sure if it was loose, troubleshoot according to the following procedure.

S00046
DI−78
− DIAGNOSTICSENGINE
1996 RAV4 (RM447U)
1 Check whether the hoses close to the fuel tank have been modified, and check
whether there are signs of any accident near the fuel tank or charcoal canister.
CHECK:
Check for cracks, deformation and loose connection of the fol-
lowing parts.
Fuel tank
Charcoal canister
Fuel tank filler pipe
Hoses and tubes around the fuel tank and charcoal
canister
NG Repair or replace.
OK
2 Check that the fuel tank cap is TOYOTA genuine parts.
NG Replace to TOYOTA genuine parts.
OK
3 Check that the fuel tank cap is correctly installed.
NG Correctly install the fuel tank cap.
OK
4 Check the fuel tank cap (See page EC−5).
NG Replace fuel tank cap.
OK

− DIAGNOSTICSENGINE
DI−79
1996 RAV4 (RM447U)
5 Check the filler neck for damage.
PREPARATION:
Remove the fuel tank cap.
CHECK:
Visually inspect the filler neck for damage.
NG Replace the filler neck.
OK
6 Check the vacuum hoses between vapor pressure sensor and VSV for vapor
pressure sensor, and VSV for vapor pressure sensor and charcoal canister.
CHECK:
(a) Check that the vacuum hose is connected correctly.
(b) Check the vacuum hose for looseness and disconnection.
(c) Check the vacuum hose for cracks, hole and damage.
NG Repair or replace.
OK
7 Check the hose and tube between fuel tank and charcoal canister.
CHECK:
(a) Check for proper connection of the fuel tank and fuel evap pipe (See page SF−1), fuel evap pipe and
fuel tube under the floor, fuel tube under the floor and charcoal canister.
(b) Check the hose and tube for cracks, hole and damage.
NG Repair or replace.
OK
8 Check the charcoal canister for cracks, hole and damage (See page EC−5).
NG Replace charcoal canister.
OK

A00389
ON
E2
(−)VC
(+)
A00409
ON
PTNK (+) E2 (−)
Vacuum
DI−80
− DIAGNOSTICSENGINE
1996 RAV4 (RM447U)
9 Check voltage between terminals VC and E2 of ECM connector.
PREPARATION:
(a) Remove side trim cover (See page SF−61).
(b) Turn ignition switch ON.
CHECK:
Measure voltage between terminals VC and E2 of ECM con-
nector.
OK:
Voltage: 4.5 − 5.5 V
NG Check and replace ECM (See page IN−30).
OK
10 Check voltage between terminals PTNK and E2 of ECM connector.
PREPARATION:
(a) Remove side trim cover (See page SF−61).
(b) Turn ignition switch ON.
CHECK:
Measure voltage between terminals PTNK and E2 of ECM con-
nector.
(1) Disconnect the vacuum hose from the vapor pres-
sure sensor.
(2) Using the MITYVAC (Hand−Held Vacuum Pump),
apply vacuum (4.0 kPa, 30 mmHg, 1.18 in. Hg) to
the vapor pressure sensor.
NOTICE:
The vacuum applied to the vapor pressure sensor must be
less than 66.7 kPa (500 mmHg).
OK:
(1) Voltage: 2.9 − 3.7 V
(2) Voltage: 0.5 V or less
OK Go to step 12.
NG
11 Check for open and short in harness and connector between vapor pressure
sensor and ECM (See page IN−30).