1996 TOYOTA TERCEL sensor

A15700
- DIAGNOSTICSENGINE
DI-57
1996 TERCEL (RM440U)
DTC P0325 Knock Sensor 1 Circuit Malfunction
CIRCUIT DESCRIPTION
A knock sensor is fitted to the cylinder block to detect engine knocking. This sensor contains a piezoelectric
element which generates a voltage when it becomes deformed, which occurs when the cylinder block vi-
brates due to knocking. If engine knocking occurs, ignition timing is retarded to suppress it.
DTC No.DTC Detection ConditionTrouble Area
P0325
No knock sensor 1 signal to ECM with engine speed 1,200 rpm
or more
(2 trip detection logic)
Open or short in knock sensor 1 circuit

Knock sensor 1 (looseness)

ECM
If the ECM detects the above diagnosis conditions, it operates the fail-safe function in which the corrective
retard angle value is set to the maximum value.
WIRING DIAGRAM
DI012-20

A15701
DI-58
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
INSPECTION PROCEDURE
1 Check continuity between terminal KNK of ECM connector and body ground.
PREPARATION:
(a) Remove the lower finish panel.
(b) Disconnect the E7 connector of ECM.
CHECK:
Measure the resistance between terminal KNK of the ECM con-
nector and the body ground.
OK:
Resistance: 1 MW or higher
OK Go to step 3.
2 Check knock sensor (See page MF-50).
NG Replace knock sensor.
OK
3 Check for open and short in harness and connector between ECM and knock
sensor (See page IN-26).
NG Repair or replace harness or connector.
OK
4 Does malfunction disappear when a good knock sensor is installed?
YES Replace knock sensor.
NO
Check and replace ECM (See page IN-26).

FI6510FI6642A07134
Knock signal waveform
0.5V/
Division
0V
0V5 m sec./Division
100 m sec./Division 0.5V/
Division
- DIAGNOSTICSENGINE
DI-59
1996 TERCEL (RM440U)
Reference: INSPECTION USING OSCILLOSCOPE

With the engine racing (4,000 rpm) measure between ter-
minal KNK of ECM and body ground.
HINT:
The correct waveform is as shown.

Spread the time on the horizontal axis, and confirm that
period of the wave is 123 m sec.
(Normal mode vibration frequency of knock sensor: 8.1
KHz.)
HINT:
If normal mode vibration frequency is not 8.1 KHz, the sensor
is malfunctioning.

A15703
DI-60
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
DTC P0335 Crankshaft Position Sensor ºAº Circuit
Malfunction
CIRCUIT DESCRIPTION
Crankshaft position sensor (NE signal) consists of a signal plate and pickup coil.
The NE signal plate has 34 teeth and is mounted on the crankshaft. The NE signal sensor generates 34
signals of 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
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

Starter

ECM
WIRING DIAGRAM
DI013-24

A01991A01992A02359
G, NE signal waveforms
5V/
Division
G
NE
20 m sec./Division (Idling)
5V/
Division
G
NE
10 m sec./Division (Idling)
- DIAGNOSTICSENGINE
DI-61
1996 TERCEL (RM440U)
INSPECTION PROCEDURE
1 Check resistance of crankshaft position sensor (See page IG-1).
Reference: INSPECTION USING OSCILLOSCOPE
During cranking or idling, check between terminals G2, NE and
NE- of ECM
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-26).
NG Repair or replace harness or connector.
OK
3 Inspect sensor installation and teeth of signal plate.
NG Tighten the sensor.
Replace signal plate.
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

DI-64
- DIAGNOSTICSENGINE
1996 TERCEL (RM440U)
3 Inspect sensor installation
NG Tighten the sensor.
OK
Check and replace ECM (See page IN-26).

A15705
A15706
- DIAGNOSTICSENGINE
DI-65
1996 TERCEL (RM440U)
DTC P0401 Exhaust Gas Recirculation Flow Insufficient
Detected
CIRCUIT DESCRIPTION
The EGR system recirculates exhaust gas, which is controlled to the proper quantity to suit the driving condi-
tions, into the intake air mixture to slow down combustion, reduce the combustion temp. and reduce NOx
emissions. The amount of EGR is regulated by the EGR vacuum modulator according to the engine load.
If even one of the following conditions is fulfilled, the VSV is
turned OFF by a signal from the ECM.
This results in atmospheric air acting on the EGR valve, closing
the EGR valve and shutting off the exhaust gas (EGR cut-off).

Before the engine is warmed up.

During deceleration (throttle valve closed).

Light engine load (amount of intake air very small).

Engine speed over 4,400 rpm.

Engine racing.
DTC No.DTC Detection ConditionTrouble Area
P0401
After the engine is warmed up, the intake manifold absolute
pressure is larger than the value calculated by the ECM while
the EGR system is ON.
(2 trip detection logic)

EGR valve stuck closed

Open or short in VSV circuit for EGR

Vacuum or EGR hose disconnected

Manifold absolute pressure sensor

EGR VSV open or close malfunction

ECM
WIRING DIAGRAM
DI95P-01