1996 TOYOTA TERCEL Service Repair Manual

A15742
A15683
- DIAGNOSTICSENGINE
DI-27
1996 TERCEL (RM440U)
4 Check for short in harness and ECM.
PREPARATION:
(a) Disconnect the intake air temp. sensor connector.
(b) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand-held tester.
OK:
Temperature value: -40°C (-40°F)
OK Replace intake air temp. sensor.
NG
5 Check for short in harness or ECM.
PREPARATION:
(a) Remove the lower finish panel.
(b) Disconnect the E7 connector of ECM.
HINT:
Intake air temperature sensor connector is disconnected.
(c) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand-held tester.
OK:
Temperature value: -40°C (-40°F)
OK Repair or replace harness or connector.
NG
Check and replace ECM (See page IN-26).

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

A15685
- DIAGNOSTICSENGINE
DI-29
1996 TERCEL (RM440U)
INSPECTION PROCEDURE
HINT:
If DTC P0105, P0106, P0110, P0115, P0120 are output simultaneously, E2 (sensor ground) may be open.
1 Connect OBD II scan tool or TOYOTA hand-held tester, and read value of engine
coolant temperature.
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) Turn the ignition switch ON and OBD II scan tool or TOYOTA hand-held tester main switch ON.
CHECK:
Read temperature value on the OBD II scan tool or TOYOTA hand-held tester.
OK:
Same value as the actual engine coolant temperature
HINT:

If there is open circuit, OBD II scan tool or TOYOTA hand-held tester indicates -40°C (-40°F).

If there is short circuit, OBD II scan tool or TOYOTA hand-held tester indicates 140°C (284°F) or more.
NG -40°C (-40°F) ... Go to step 2.
140°C (284°F) or more ... Go to step 4.
OK
Check for intermittent problems (See page
DI-3).
2 Check for open in harness or ECM.
PREPARATION:
(a) Disconnect the engine coolant temp. sensor connector.
(b) Connect sensor wire harness terminals together.
(c) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand-held tester.
OK:
Temperature value: 140°C (284°F) or more
OK Confirm good connection at sensor. If OK, re-
place engine coolant temp. sensor
NG

A15686
A15687
DI-30
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
3 Check for open in harness or ECM.
PREPARATION:
(a) Remove the lower finish panel.
(b) Connect terminals THW and E2 of ECM connector to-
gether.
HINT:
Engine coolant temperature sensor connector is disconnected.
Before checking, do a visual and contact pressure check for the
ECM connector (See page IN-26).
(c) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand-held tester.
OK:
Temperature value: 140°C (284°F) or more
OK Open in harness between terminal E2 or termi-
nal THW, repair or replace harness.
NG
Confirm good connection at ECM.
If OK, replace ECM.
4 Check for short in harness and ECM.
PREPARATION:
(a) Disconnect the engine coolant temperature sensor con-
nector.
(b) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand-held tester.
OK:
Temperature value: -40°C (-40°F)
OK Replace engine coolant temperature sensor.
NG

A15688
- DIAGNOSTICSENGINE
DI-31
1996 TERCEL (RM440U)
5 Check for short in harness or ECM.
PREPARATION:
(a) Remove the lower finish panel.
(b) Disconnect the E7 connector of ECM.
HINT:
The engine coolant temperature sensor connector is discon-
nected.
(c) Turn the ignition switch ON.
CHECK:
Read the temperature value on the OBD II scan tool or TOYO-
TA hand-held tester.
OK:
Temperature value: -40°C (-40°F)
OK Repair or replace harness or connector.
NG
Check and replace ECM (See page IN-26).

DI-32
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
DTC P0116 Engine Coolant Temp. Circuit Range/
Performance Problem
CIRCUIT DESCRIPTION
Refer to Engine Coolant Temp. Circuit Malfunction on page DI-28.
DTC No.DTC Detection ConditionTrouble Area
P0116
20 min. or more after the engine starts, engine coolant
temp. sensor value is 40°C (104°F) or less (2 trip detection
logic)
Engine coolant temp. sensor

Cooling system
INSPECTION PROCEDURE
HINT:
If DTC P0115 and P0116 are output Simultaneously, engine coolant temperature sensor circuit may be open.
Perform troubleshooting of DTC P0115 first.
1 Are there any other codes (besides DTC P0116) being output?
YES Go to relevant DTC chart.
NO
2 Check thermostat (See page CO-10).
NG Replace thermostat.
OK
Replace engine coolant temp. sensor.
DI1E7-08

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

A15689
FI7052
DI-34
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
WIRING DIAGRAM
INSPECTION PROCEDURE
HINT:
If DTC P0105, P0110, P0120 are output simultaneously, E2 (sensor ground) may be open.
1 Connect OBD II scan tool or TOYOTA hand-held tester and read throttle valve
opening percentage.
PREPARATION:
(a) Remove the fuse cover on the instrument panel.
(b) Connect the OBD II scan tool or TOYOTA hand-held tes-
ter to the DLC3.
(c) Turn the ignition switch ON and OBD II scan tool or TOY-
OTA hand-held tester main switch ON.
CHECK:
Read the throttle valve opening percentage.
OK:
Throttle valveThrottle valve opening
position expressed as percentage
Fully openApprox. 70 %
Fully closedApprox. 10 %
OK Check for intermittent problems
(See page DI-3).
NG