sensor TOYOTA TERCEL 1996 Service Manual Online

DI-68
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
4 Check EGR vacuum modulator (See page EC-7).
NG Repair or replace.
OK
5 Check EGR valve (See page EC-7).
NG Repair or replace.
OK
6 Check manifold absolute pressure sensor (See page DI-23).
NG Repair or replace.
OK
Check and replace ECM (See page IN-26).
OBD II scan tool (excluding TOYOTA hand-held tester):
1 Check connection of vacuum hose, EGR hose (See page EC-2).
NG Repair or replace.
OK

DI-70
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
5 Check EGR valve (See page EC-7).
NG Repair or replace.
OK
6 Check manifold absolute pressure sensor (See page DI-23).
NG Repair and replace.
OK
Check and replace ECM (See page IN-26).

- DIAGNOSTICSENGINE
DI-71
1996 TERCEL (RM440U)
DTC P0402 Exhaust Gas Recirculation Flow Excessive
Detected
CIRCUIT DESCRIPTION
Refer to DTC P0402 on page DI-65.
DTC No.DTC Detection 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
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 connection of vacuum hose, EGR hose (See page EC-2).
NG Repair or replace.
OK
2 Check EGR valve (See page EC-7).
NG Repair or replace.
OK
3 Check VSV for EGR (See page DI-65).
OK Go to step 5.
NG
DI95Q-01

DI-72
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
4 Check operation of the for EGR (See page EC-7).
NG Replace VSV for EGR.
OK
Check for open and short in harness and con-
nector between engine room R/B and ECM
(See page IN-26).
5 Check EGR vacuum modulator (See page EC-7).
NG Repair or replace.
OK
6 Check manifold absolute pressure sensor (See page DI-23).
NG Repair or replace.
OK
Check and replace ECM (See page IN-26).

FI7081
Waveform of Oxygen Sensor
before CatalystNormal CatalystWaveform of Oxygen
Sensor after Catalyst
- DIAGNOSTICSENGINE
DI-73
1996 TERCEL (RM440U)
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 waveforms change at a similar rate, it indicates that catalyst performance has deteriorated.
DTC No.DTC Detection ConditionTrouble Area
P0420
After the engine and the catalyst are warmed up, and while
vehicle is driven within the set vehicle and engine speed
range, the waveforms of the oxygen sensor (bank 1 sensor 1)
and heated oxygen sensor (bank 1 sensor 2) have the same
amplitude (2 trip detection logic)

Three-way catalytic converter

Open or short in (heated) oxygen sensor circuit

(Heated) oxygen sensor
DI1EE-18

FI7132
Engine Speed
2,500 - 3,000 rpm
Idling
IG SW OFF
Warmed up3 min. or soCheckTime (a)(c)
(d)
(b)
FI6514
OX Signal Waveform (Oscilloscope)
1.0 V
0 V
200 m sec. /Division
DI-74
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
CONFIRMATION ENGINE RACING PATTERN
(a) Connect the TOYOTA hand-held tester to the DLC3, or connect the probe of the oscilloscope between
terminals OX1, OX2 and E1 of ECM.
(b) Start engine and warm it up with all accessories switched OFF until engine coolant temperature is
stable.
(c) Race the engine at 2,500 - 3,000 rpm for about 3 minutes.
(d) After confirming that the waveform of the oxygen sensor, bank 1 sensor 1 (OX1), oscillate around 0.5
V during feedback to the ECM, check the waveform of the heated oxygen sensor, bank 1 sensor 2
(OX2).
HINT:
If there is a malfunction in the system, the waveform of the
heated oxygen sensor, bank 1 sensor 2 (OX2), is almost the
same as that of the oxygen sensor, bank 1 sensor 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.
INSPECTION PROCEDURE
1 Are there any other codes (besides DTC P0420) being output?
YES Go to relevant DTC chart.
NO
2 Check heated oxygen sensor (bank 1 sensor 2) (See page DI-44).

DI-44
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
DTC P0133 Oxygen Sensor Circuit Slow Response
(Bank 1 Sensor 1)
CIRCUIT DESCRIPTION
Refer to DTC P0125 on page DI-38 .
DTC No.DTC Detection ConditionTrouble Area
P0133
Response time for oxygen sensor's voltage output to
change from rich to lean, or from lean to rich, is 1 sec. or
more during idling after the engine is warmed up
(2 trip detection logic)

Oxygen sensor
HINT:
Sensor 1 refers to the sensor closer to the engine body.
INSPECTION PROCEDURE
1 Are there any other codes (besides DTC P0133) being output?
YES Go to relevant DTC chart.
NO
Replace oxygen sensor.
DI1EC-07

A15711
P19752
Combination Meter
C8611
SPD5 V
E8 Y
C9
7 Speed
Sensor
BR
ID
ECM DI-76
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
DTC P0500 Vehicle Speed Sensor Malfunction
CIRCUIT DESCRIPTION
This sensor is mounted in the combination meter. It contains a magnet which is rotated by the speedometer
cable.
Turning the reed switch ON and OFF 4 times for every revolution of the speedometer.
It is then transmitted to the ECM. The ECM determines the vehicle speed based on the frequency of these
pulse signals.
DTC No.DTC Detection ConditionTrouble Area
P0500
No vehicle speed sensor signal to ECM when vehicle is being
driven
(2 trip detection logic)
Open or short in vehicle speed sensor circuit

Vehicle speed sensor

Speedometer cable

ECM
WIRING DIAGRAM
DI01B-23

A15713
AT7809
4.5 - 5.5 V
0
Turn the wheel
- DIAGNOSTICSENGINE
DI-77
1996 TERCEL (RM440U)
INSPECTION PROCEDURE
1 Check operation of speedometer.
CHECK:
Drive the vehicle and check if the operation of the speedometer in the combination meter is normal.
HINT:
The vehicle speed sensor is operating normally if the speedometer display is normal.
NG Check speedometer circuit. See combination
meter troubleshooting.
OK
2 Check voltage between terminal SPD of ECM connector and body ground.
PREPARATION:
(a) Remove the lower finish panel.
(b) Shift the shift lever to neutral.
(c) Jack up one of the front wheels.
(d) Turn the ignition switch ON.
CHECK:
Measure the voltage between terminal SPD of the ECM con-
nector and the body ground when the wheel is turned slowly.
OK:
Voltage is generated intermittently.
NG Check and repair harness and connector be-
tween combination meter and ECM.
OK
Check and replace ECM (See page IN-26).

A15717
- DIAGNOSTICSENGINE
DI-81
1996 TERCEL (RM440U)
DTC P0510 Closed Throttle Position Switch Malfunction
CIRCUIT DESCRIPTION
Refer to DTC P0120 on page DI-33.
DTC No.DTC Detection ConditionTrouble Area
P0510Closed throttle position switch does not turn ON even once
when vehicle is driven (2 trip detection logic)
Open in closed throttle position switch circuit

Closed throttle position switch

ECM
HINT:
After confirming DTC P0510, use the TOYOTA hand-held tester to confirm the closed throttle position switch
signal from the CURRENT DATA.
Throttle ValveClosed Throttle Position Switch SignalMalfunction
Fully closedOFFOpen circuit
Fully openONShort circuit
WIRING DIAGRAM
Refer to DTC P0120 on page DI-33.
INSPECTION PROCEDURE
HINT:
If DTCs P0110, P0115 and P0120 are output simultaneously, E2 (sensor ground) may be open.
TOYOTA hand-held tester:
1 Check for open in harness or ECM.
PREPARATION:
(a) Connect the TOYOTA hand-held tester to the DLC3.
(b) Disconnect the throttle position sensor connector.
(c) Connect the sensor wire harness terminals between ter-
minals 3 and 4.
(d) Turn the ignition switch ON.
CHECK:
Read thg CTP switch signal on the TOYOTA hand-held tester.
OK:
CTP switch signal: ON
OK Confirm good connection at sensor. If OK, re-
place throttle position sensor.
NG
DI95R-01