air condition TOYOTA TERCEL 1996 Service Owner's Manual

DI1E3-06
P01242
750
450
100 (3.96)
3.6
1.2
(840) 2.4
150
60 20
(112)kPa mmHg
Manifold Absolute Pressure
Output Voltage
V DI-20
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
CIRCUIT INSPECTION
DTC P0105 Manifold Absolute Pressure/Barometric
Pressure Circuit Malfunction
CIRCUIT DESCRIPTION
By a built-in sensor unit, the manifold absolute pressure sensor
detects the intake manifold pressure as a voltage. The ECM
then determines the basic injection duration and basic injection
advance angle based on this voltage. Since the manifold abso-
lute pressure sensor does not use the atmospheric pressure as
a criterion, but senses the absolute pressure inside the intake
manifold (the pressure in proportion to the present absolute
vacuum 0), it is not influenced by fluctuations in the atmospheric
pressure due to high altitude and other factors. This permits it
to control the air-fuel ratio at the proper lever under all condi-
tions.
DTC No.DTC Detection ConditionTrouble Area
P0105Open or short manifold absolute pressure sensor circuit

Open or short in manifold absolute pressure sensor circuit

Manifold absolute pressure sensor

ECM
If the ECM detects DTC P0105, it operates the fail-safe function, keeping the ignition timing and injection
volume constant and making it possible to drive the vehicle.
HINT:
After confirming DTC P0105, use the OBDII scan tool or TOYOTA hand-held tester to confirm the manifold
absolute pressure from the CURRENT DATA.
Manifold absolute pressureTrouble Area
0 kPaPIM circuit short
130 kPa or more
VC circuit open or short
PIM circuit open
E2 circuit open

FI4741 (-4) 0.1 0.2
0 -20 0.3 0.51 2 35 10 20 30
20 40 60 80 100
(32) (68) (104) (140) (212)(176)
Resistance kW
Acceptable
Temp.°C (°F) (fig.1)
DI-24
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
DTC P0110 Intake Air Temp. Circuit Malfunction
CIRCUIT DESCRIPTION
The intake air temperature sensor is built into the air cleaner
cap and senses the intake air temperature. A thermistor built in
the sensor changes the resistance value according to the in-
take air temperature. The lower the intake air temperature, the
greater the thermistor resistance value, and the higher the in-
take air temperature, the lower the thermistor resistance value
(See Fig. 1). The intake air temperature sensor is connected to
the ECM (See next page). The 5 V power source voltage in the
ECM is applied to the intake air temperature sensor from the ter-
minal THA via a resistor R. That is, the resistor R and the intake
air temp. sensor are connected in series. When the resistance
value of the intake air temperature sensor changes in accor-
dance with changes in the intake air temperature, the potential
at terminal THA also changes. Based on this signal, the ECM
increases the fuel injection volume to improve driveability dur-
ing cold engine operation.
If the ECM detects the DTC ºP0110º, it operates the fail-safe
function in which the intake air temperature is assumed to be
20° (68°F).
Reference
Intake air temp.
°C (°F)Resistance
(kW)Voltage
(V)
-20 (-4)16.24.3
0 (32)5.93.4
20 (68)2.52.4
40 (104)1.11.5
60 (140)0.60.9
80 (176)0.30.5
100 (212)0.20.3
DTC No.DTC Detecting ConditionTrouble Area
P0110Open or short in intake air temp. sensor circuit

Open or short in intake air temp. sensor circuit

Intake air temp. sensor

ECM
HINT:
After confirming DTC P0110, use the OBD II scan tool or TOYOTA hand-held tester to confirm the intake
air temperature from the CURRENT DATA.
Temperature DisplayedMalfunction
-40°C (-40°F)Open circuit
140°C (284°F) or moreShort circuit
DI1E5-08

A10940
ECM
E7
E7 G-B
BR5V
E1 E2 THW
2
1 Engine Coolant Temp. Sensor
3
16 DI-28
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
DTC P0115 Engine Coolant Temp. Circuit Malfunction
CIRCUIT DESCRIPTION
A thermistor built into the engine coolant temperature sensor changes the resistance value according to the
engine coolant temperature. The structure of the sensor and connection to the ECM is the same as in the
intake air temp. circuit malfunction shown on page DI-24.
If the ECM detects the DTC P0115, it operates the fail-safe function in which the engine coolant temp. is
assumed to be 80°C (176°F).
DTC No.DTC Detection ConditionTrouble Area
P0115Open or short in engine coolant temp. sensor circuit

Open or short in engine coolant temp. sensor circuit

Engine coolant temp. sensor

ECM
HINT:
After confirming DTC P0115, use the OBD II scan tool or TOYOTA hand-held tester to confirm the engine
coolant temperature from the CURRENT DATA.
Temperature DisplayedMalfunction
-40°C (-40°F)Open circuit
140°C (284°F) or moreShort circuit
WIRING DIAGRAM
DI1E6-08

P24296
Throttle Position
Sensor
E2 VTAECM
VC
- DIAGNOSTICSENGINE
DI-33
1996 TERCEL (RM440U)
DTC P0120 Throttle/Pedal Position Sensor/Switch ºAº
Circuit Malfunction
CIRCUIT DESCRIPTION
The throttle position sensor is mounted in the throttle body and
detects the throttle valve opening angle. When the throttle valve
is fully closed, a voltage of approximately 0.3 - 0.8 V is applied
to terminal VTA of the ECM. The voltage applied to the terminal
VTA of the ECM increases in proportion to the opening angle
of the throttle valve and becomes approximately 3.2 - 4.9 V
when the throttle valve is fully opened. The ECM judges the ve-
hicle driving conditions from these signals input from terminal
VTA and uses them as one of the conditions for deciding the
air-fuel ratio correction, power increases correction and fuel-
cut control etc.
DTC No.DTC Detection ConditionTrouble Area
P0120
Condition (a) or (b) continues:
(a) VTA < 0.1 V
(b) VTA > 4.9 V
Open or short in throttle position sensor circuit

Throttle position sensor

ECM
HINT:
After confirming DTC P0120, use the OBD II scan tool or TOYOTA hand-held tester to confirm the throttle
valve opening percentage.
Throttle valve opening position expressed as percentageTblAThrottle valve fully closedThrottle valve fully openTrouble Area
0 %0 %VC line open
VTA line open or short
100 %100 %E2 line open
DI1E8-08

P19660 FI17210A00855
Atmosphere
Housing
Platinum Electrode
Solid Electrolyte
(Zirconia Element)
Platinum Electrode
Coating (Ceramic)
Exhaust Gas
CoverIdeal Air-Fuel Mixture
Output Voltage
Richer - Air Fuel Ratio - Leaner
DI-38
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
DTC P0125 Insufficient Coolant Temp. for Closed Loop
Fuel Control
CIRCUIT DESCRIPTION
To obtain a high purification rate for the CO, HC and NOx components of the exhaust gas, a three-way cata-
lytic converter is used, but for the most efficient use of the three-way catalytic converter, the air-fuel ratio
must be precisely controlled so that it is always close to the stoichiometric air-fuel ratio.
The heated oxygen sensor has the characteristic whereby its output voltage changes suddenly in the vicinity
of the stoichiometric air-fuel ratio. This characteristic is used to detect the oxygen concentration in the ex-
haust gas and provide feedback to the computer for control of the air-fuel ratio.
When the air-fuel ratio becomes LEAN, the oxygen concentration in the exhaust increases and the oxygen
sensor informs the ECM of the LEAN condition (small electromotive force: 0 V).
When the air-fuel ratio is RICHER than the stoichiometric air-fuel ratio the oxygen concentration in the ex-
haust gas is reduced and the oxygen sensor informs the ECM of the RICH condition (large electromotive
force: 1 V).
The ECM judges by the electromotive force from the oxygen sensor whether the air-fuel ratio is RICH or
LEAN and controls the injection time accordingly. However, if malfunction of the oxygen sensor causes out-
put of abnormal electromotive force, the ECM is unable to perform accurate air-fuel ratio control.
DTC No.DTC Detection ConditionTrouble Area
P0125
After the engine is warmed up, oxygen sensor output does
not indicate RICH even once when conditions (a), (b) and
(c) continue for at least 1.5 minutes:
(a) Engine speed: 1,500 rpm or more
(b) Vehicle speed: 40 - 100 km/h (25 - 62 mph)
(c) Throttle valve does not fully closed

Open or short in oxygen sensor circuit

Oxygen sensor
HINT:
After confirming DTC P0125, use the OBD II scan tool or TOYOTA hand-held tester to confirm voltage output
of the heated oxygen sensor from the CURRENT DATA. If voltage output of the heated oxygen sensor is
0 V, heated oxygen sensor circuit may be open or short.
DI1EA-08

DI-42
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
INSPECTION PROCEDURE
1 Check for open and short in harness and connector between ECM and oxygen
sensor (See page IN-26).
NG Repair or replace harness or connector.
OK
2 Check for oxygen sensor data.
PREPARATION:
(a) Remove the fuse cover on the instrument panel.
(b) Connect the OBD II scan tool or TOYOTA hand-held tester to the DLC3.
(c) Warm up engine to normal operating temperature.
CHECK:
Read the oxygen sensor output voltage and short-term fuel trim.
RESULT:
PatternOxygen sensor output voltageShort-term fuel trim
1Lean condition (Changes at 0.55 V or less)Changes at about +20 %
2Rich condition (Changes at 0.4 V or more)Changes at about -20 %
3Except 1 and 2
1, 2 Check fuel trim system (See page DI-49).
3

- DIAGNOSTICSENGINE
DI-45
1996 TERCEL (RM440U)
DTC P0136 Heated Oxygen Sensor Circuit Malfunction
(Bank 1 Sensor 2)
CIRCUIT DESCRIPTION
Refer to DTC P0125 on page DI-38.
DTC No.DTC Detection ConditionTrouble Area
P0136
Voltage output of the heated oxygen sensor (bank 1 sensor 2)
remains at 0.4 V or more, or 0.5 V or less when the vehicle is
driven at 50 km/h (31 mph) or more after the engine is warmed
up
(2 trip detection logic).

Heated oxygen sensor
HINT:
Sensor 2 refers to the sensor farther away from the engine body.
WIRING DIAGRAM
Refer to page DI-38.
INSPECTION PROCEDURE
1 Are there any other codes (besides DTC P0136) being output?
YES Go to relevant DTC chart.
NO
2 Check for open and short in harness and connector between ECM and heated
oxygen sensor (See page IN-26).
NG Repair or replace harness or connector.
OK
DI00Y-21

- DIAGNOSTICSENGINE
DI-49
1996 TERCEL (RM440U)
DTC P0171 System too Lean (Fuel Trim)
DTC P0172 System too Rich (Fuel Trim)
CIRCUIT DESCRIPTION
ºFuelº trim refers to the feedback compensation value compared against the basic injection time. Fuel trim
includes short-term fuel trim and long-term fuel trim.
ºShort-term fuel trimº is the short-term fuel compensation used to maintain the air-fuel ratio at its ideal
theoretical value. The signal from the oxygen sensor indicates whether the air-fuel ratio is RICH or LEAN
compared to the ideal theoretical value, triggering a reduction in fuel volume if the air-fuel ratio is rich, and
an increase in fuel volume if it is lean.
ºLong-term fuel trimº is overall fuel compensation carried out long-term to compensate for continual devi-
ation of the short-term fuel trim form the central value due to individual engine differences, wear over time
and changes in the usage environment.
If both the short-term fuel trim and long-term fuel trim are LEAN or RICH beyond a certain value, it is de-
tected as a malfunction and the MIL lights up.
DTC No.DTC Detection ConditionTrouble Area
P0171
When the air-fuel ratio feedback is stable after engine warming
up, the fuel trim is considerably in error on the RICH side
(2 trip detection logic)

Air intake (hose loose)

Fuel line pressure

Injector blockage

Heated oxygen sensor malfunction

Manifold absolute pressure sensor

Engine coolant temp. sensor
P0172
When the air-fuel ratio feedback is stable after engine warming
up, the fuel trim is considerably in error on the LEAN side.
(2 trip detection logic)

Fuel line pressure

Injector blockage, leak

Heated oxygen sensor malfunction

Manifold absolute pressure sensor

Engine coolant temp. sensor
HINT:

When DTC P0171 is recorded, the actual air-fuel ratio is on the LEAN side. When DTC P0172 is re-
corded, the actual air-fuel ratio is on the RICH side.

If the total of the short-term fuel trim value and long-term fuel trim value is within + 25 %, the system
is functioning normally.

If the vehicle runs out of fuel, the air-fuel ratio is LEAN and DTC P0171 is recorded. The MIL then
comes on.
DI052-09

DI-50
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
INSPECTION PROCEDURE
1 Check air induction system (See page MF-1).
NG Repair or replace.
OK
2 Check for heated oxygen sensor data.
PREPARATION:
(a) Remove the fuse cover on the instrument panel.
(b) Connect the OBD II scan tool or TOYOTA hand-held tester to the DLC3.
(c) Warm up engine to normal operating temperature.
CHECK:
Read the oxygen sensor output voltage and short-term fuel trim.
RESULT:
PatternOxygen sensor output voltageShort-term fuel trim
1Lean condition (Changes at 0.55 V or less)Changes at about + 20 %
2RIch condition (Changes at 0.4 V or more)Changes at about - 20 %
3Except 1 and 2
3 Check for oxygen sensor
(See page DI-41).
1, 2
3 Check fuel pressure (See page MF-1).
NG Check and repair fuel pump, pressure regulator,
fuel pipe line and filter. (See page MF-5)
OK

- DIAGNOSTICSENGINE
DI-63
1996 TERCEL (RM440U)
DTC P0340 Camshaft Position Sensor Circuit
Malfunction
CIRCUIT DESCRIPTION
Camshaft position sensor (G signal) consist of signal plate and pickup coil.
The G signal plate has one tooth on its outer circumference and is mounted on the exhaust camshaft.
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 mounted on the crankshaft. The NE signal sensor generates 34
signals for every engine revolution. The ECM detects the standard crankshaft angle based on the G signals
and the actual crankshaft angle and the engine speed by the NE signals.
DTC No.DTC Detection 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

Starter

ECM
WIRING DIAGRAM
Refer to DI-60.
INSPECTION PROCEDURE
1 Check resistance of camshaft position sensor (See page IG-1).
Reference: INSPECTION USING OSCILLOSCOPE
Refer to page DI-60.
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-26).
NG Repair or replace harness or connector.
OK
DI014-23