1996 TOYOTA TERCEL Block

- 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

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

DI4LU-03
W00704
ABS
EA2 2
DLC1 F71
F63
5
MAIN FL
BatteryEngine Room R/B
L
4
12
21L
A6
A71
2
A7A6
A6
A7 6
2
A6
A71Motor Relay
EB
7
ABS ECU
G-R
L-B
G-B
W-B
W-B
EA
A5
A5A5
A5
A5 12
4
3
5LG
LG-B ABS ECU L-WR+MR
A12
A12
A12
A12SR
AST
MT 4
20
8
26
ABS
EA2 2
F71
ALT
F63
5
MAIN FL
BatteryEngine Room R/B
4
1 B-Y
B2
LA6
A71
2
A7A6
A6
A7 6
A6
A7Solenoid
RelayMotor Relay ABS Control Relay
7
G-R
L-B
G-B W-B
W-B
W-B
W-B W-B
A5
A5A5
A5
A5 12
4
LG
LG-B
ABS ActuatorR+MR
SR
AST
MT 4
20
26 Fuse
BlockA12
B-Y2
- DIAGNOSTICSANTI-LOCK BRAKE SYSTEM
DI-1 19
1996 TERCEL (RM440U)
CIRCUIT INSPECTION
DTC 11, 12 ABS Control (Solenoid) Relay Circuit
CIRCUIT DESCRIPTION
This relay supplies power to each ABS solenoid. After the ignition switch is turned ON, if the initial check is
OK, the relay goes on.
DTC No.DTC Detecting ConditionTrouble Area
11
Conditions 1 and 2 continue for 0.2 sec. or more:
1. ABS control (solenoid) relay terminal (SR) voltage:
Battery positive voltage
2. ABS control (solenoid) relay monitor terminal (AST) volt-
age: 0 V

ABS control (solenoid) relay

Open or short in ABS control (solenoid) relay circuit

ECU
12
Conditions 1 and 2 continue for 0.2 sec. or more:
1. ABS control (solenoid) relay terminal (SR) voltage: 0 V
2. ABS control (solenoid) relay monitor terminal (AST) volt-
age: Battery positive voltage
ABS control (solenoid) relay

B+ short in ABS control (solenoid) relay circuit

ECU
Fail safe function:
If trouble occurs in the ABS control (solenoid) relay circuit, the ECU cuts off current to the ABS control (sole-
noid) relay and prohibits ABS control.
WIRING DIAGRAM

W00704
ABS
EA2 2
DLC1 F71
F63
5
MAIN FL
BatteryEngine Room R/B
L
4
12
21L
A6
A71
2
A7A6
A6
A7 6
2
A6
A71Motor Relay
EB
7
ABS ECU
G-R
L-B
G-B
W-B
W-B
EA
A5
A5A5
A5
A5 12
4
3
5LG
LG-B ABS ECU L-WR+MR
A12
A12
A12
A12SR
AST
MT 4
20
8
26
ABS
EA2 2
F71
ALT
F63
5
MAIN FL
BatteryEngine Room R/B
4
1 B-Y
B2
LA6
A71
2
A7A6
A6
A7 6
A6
A7Solenoid
RelayMotor Relay ABS Control Relay
7
G-R
L-B
G-B W-B
W-B
W-B
W-B W-B
A5
A5A5
A5
A5 12
4
LG
LG-B
ABS ActuatorR+MR
SR
AST
MT 4
20
26 Fuse
BlockA12
B-Y2 DI-122
- DIAGNOSTICSANTI-LOCK BRAKE SYSTEM
1996 TERCEL (RM440U)
DTC 13, 14 ABS Control (Motor) Relay Circuit
CIRCUIT DESCRIPTION
The ABS control (motor) relay supplies power to the ABS pump motor. While the ABS is activated, the ECU
switches the ABS control (motor) relay on and operates the ABS pump motor.
DTC No.DTC Detecting ConditionTrouble Area
13
Conditions 1 and 2 continue for 0.2 sec. or more:
1. ABS control (motor) relay terminal (MR) voltage:
Battery positive voltage
2. ABS control (motor) relay monitor terminal (MT) voltage:
0 V

ABS control (motor) relay

Open or short in ABS control (motor) relay circuit

ECU
14
Conditions 1 and 2 continued for 4 sec. or more:
1. ABS control (motor) relay terminal (MR) voltage: 0 V
2. ABS control (motor) relay monitor terminal (MT) voltage:
Battery positive voltage
ABS control (motor) relay

B+ short in ABS control (motor) relay circuit

ECU
Fail safe function:
If trouble occurs in the ABS control (motor) relay circuit, the ECU cuts off the current to the ABS control (sole-
noid) relay and prohibits ABS control.
WIRING DIAGRAM
DI4LV-03

W00705F15132
22
1 2ABS
Battery
B-Y
B
Fuse
Block
W-B
EA
EB
1
W-B
11
W-B
2
2 5
4 L
66
14
DLC1
ABS Control
Relay
Solenoid
Relay
P
R-B
R-W
L-W
G-Y
ABS ECUABS ECU
7 3
8 4
5 1
121 2
SFLR
SFLH
SFRR
SFRH
SRRR
SRRH A6
A5A13
A7 A7
A7
A6A13
A12
A12
A12
A12
Y-R
F7Y
F6Engine Room R/B
L
W-B
W-B
SRLR SRLH A13
A13
B-R
1ABS ECU
ABS ECU
ABS ECU
A4
A4
A4
A4
A4
A4
A4
A4
A5
A56Y
Y
Y-R
Y-R
Y-B Y-B
5
2
15
11
MAIN
FL
ALT
EA2
IC2IE1
IE1 IC2
IC2IE1
IE1 IC2
6
1
14
2
5
43
13 2
ABS Actuator LMotor
Relay
2
G-Y
Y-B
G-Y
Monitor
L-WL-R
R14675
4321
5 6 7 8
4
A5 A4
4321
5 6 7 8
4
A5 A4
4321
5 6 7 8
4
A5 A4
4321
5 6 7 8
4
A5 A4
4321
5 6 7 8
4
A5 A44321
5 6 7 8
4
A5 A4
DI-126
- DIAGNOSTICSANTI-LOCK BRAKE SYSTEM
1996 TERCEL (RM440U)
WIRING DIAGRAM
INSPECTION PROCEDURE
1 Check ABS actuator solenoid.
PREPARATION:
Disconnect the 2 connectors from the ABS actuator.
CHECK:
Check the continuity between terminals A5-4 and A4-1, 2, 3,
4, 5, 6, 7, 8 of the ABS actuator connector.
OK:
Continuity
HINT:

Resistance of each of the solenoids SFRH, SFLH, SRRH
and SRLH is 5.0 W.

Resistance of each of the solenoids SFRR, SFLR, SRRR
and SRLR is 2.2 W.
NG Replace ABS actuator.
OK

W00706
Battery MAIN FLECU-IG
4
1Ignition Switch
2A12
7
GND
EA21J
1L-R
F6
F7B
B-YB-Y
5 B
IG1
W-B 2 2 1 2
W-B W-G2
1
1B Driver Side J/B
W-G
2Driver Side J/B
1B1K
2
2 B
Junction
Connector
B-Y
W-B W-B
GND A13
A1310 21
Battery MAIN FLECU-IG
4
1Ignition Switch
2A12
7
GND
EA21J
1L-R
F6
F7B
B-YB-Y
5 B
IG1
W-B 2 2 1 2
W-B W-G2
1
1B Driver Side J/B
W-G
2Driver Side J/B
1B1K
2
2 BJunction
Connector
B-Y
W-B W-B
GND A13
A1310 21
Battery MAIN FLECU-IG
4
1Ignition Switch
2A12
7
GND
EA21J
1L-R
F6
F7B
B-YB-Y
5 B
IG1
W-B 2 2 1 2
W-B W-G2
1
1B Driver Side J/B
W-G
2Driver Side J/B
1B1K
2
2 BJunction
Connector
B-Y
W-B W-B
GND A13
A1310 21
Battery MAIN FLECU-IG
4
1Ignition Switch
2A12
7
GND
EA21J
1L-R
F6
F7B
B-YB-Y
5 B
IG1
W-B Fuse
Block
2 1 2
W-B W-G2
1
1B Driver Side J/B
W-G
2Driver Side J/B
1B1K
2
2 BJunction
Connector
B-Y
W-B W-B
GND A13
A1310 21
Battery MAIN FLECU-IG
4
1Ignition Switch
2A12
7
GND
EA21J
1L-R
F6
F7B
B-YB-Y
5 B
IG1
W-B
ALT
B-Y
2 1 2
AM1
W-B W-G2
1
1B Driver Side J/B
W-G
2Driver Side J/B
1B1K
2
2 B
Junction
Connector
B-Y
W-B W-B
GND A13
A1310 21
BH
BG
Engine Room R/BEngine Room R/BABS ECU DI-132
- DIAGNOSTICSANTI-LOCK BRAKE SYSTEM
1996 TERCEL (RM440U)
DTC 41 IG Power Source Circuit
CIRCUIT DESCRIPTION
This is the power source for the ECU and, hence the CPU and the actuators.
DTC No.DTC Detecting ConditionTrouble Area
41
Vehicle speed is 3 km/h (1.9 mph) or more and voltage of
ECU terminal IG1 remains at more than 17 V or below 9.5
V for more than 10 sec.
Battery

IC regulator

Open or short in power source circuit

ECU
Fail safe function:
If trouble occurs in the power source circuit, the ECU cuts off current to the ABS control (solenoid) relay and
prohibits ABS control.
WIRING DIAGRAM
DI4R7-03

W00704
ABS
EA2 2
DLC1 F71
F63
5
MAIN FL
BatteryEngine Room R/B
L
4
12
21L
A6
A71
2
A7A6
A6
A7 6
2
A6
A71Motor Relay
EB
7
ABS ECU
G-R
L-B
G-B
W-B
W-B
EA
A5
A5A5
A5
A5 12
4
3
5LG
LG-B ABS ECU L-WR+MR
A12
A12
A12
A12SR
AST
MT 4
20
8
26
ABS
EA2 2
F71
ALT
F63
5
MAIN FL
BatteryEngine Room R/B
4
1 B-Y
B2
LA6
A71
2
A7A6
A6
A7 6
A6
A7Solenoid
RelayMotor Relay ABS Control Relay
7
G-R
L-B
G-B W-B
W-B
W-B
W-B W-B
A5
A5A5
A5
A5 12
4
LG
LG-B
ABS ActuatorR+MR
SR
AST
MT 4
20
26 Fuse
BlockA12
B-Y2
- DIAGNOSTICSANTI-LOCK BRAKE SYSTEM
DI-135
1996 TERCEL (RM440U)
DTC 51 ABS Pump Motor Lock
CIRCUIT DESCRIPTION
DTC No.DTC Detecting ConditionTrouble Area
51Pump motor is not operating normally during initial check
ABS pump motor
Fail safe function:
If trouble occurs in the ABS pump motor, the ECU cuts off the current to the ABS control (solenoid) relay and
prohibits ABS control.
WIRING DIAGRAM
DI4LX-02

W03008
Battery MAIN FL
Fuse BlockALT Driver Side J/B
B 1 1
F6 F7 B-R EA2 2B-R1 1
1J 1CSTOP
G-W
BH
12ABS ECU IF12
G-R
21 Stop Light Switch
R-W
IE11
G-W
1E 1
1
1L
1K 5
G-W G-W
Stop Light
W-BA12STP Driver Side J/B
DI-136
- DIAGNOSTICSANTI-LOCK BRAKE SYSTEM
1996 TERCEL (RM440U)
Stop Light Switch Circuit
CIRCUIT DESCRIPTION
This stop light switch senses whether the brake pedal is depressed or released, and sends the signal to the
ECU.
WIRING DIAGRAM
INSPECTION PROCEDURE
1 Check operation of stop light.
CHECK:
Check that stop light lights up when brake pedal is depressed and turns off when brake pedal is released.
NG Repair stop light circuit (See page BE-28)
OK
DI4LY-02