1996 TOYOTA TERCEL ECU

- DIAGNOSTICSANTI-LOCK BRAKE SYSTEM
DI-127
1996 TERCEL (RM440U)
2 Check for open and short in harness and connector between ABS ECU and ac-
tuator (See page IN-26).
NG Repair or replace harness or connector.
OK
If same code is still output after DTC is deleted, check contact condition of each connection. If
connections are normal, ECU may be defective.

BR3583
BR3582F00010
RotorSpeed Sensor
Magnet
To ECU
+V
-VHigh Speed
Low Speed
CoilNS
0 DI-128
- DIAGNOSTICSANTI-LOCK BRAKE SYSTEM
1996 TERCEL (RM440U)
DTC 31, 32, 33, 34 Speed Sensor Circuit
CIRCUIT DESCRIPTION
The speed sensor detects wheel speed and sends the ap-
propriate signals to the ECU. These signals are used to control
the ABS system. The front and rear rotors each have 48 serra-
tions.
When the rotors rotate, the magnetic field emitted by the perma-
nent magnet in the speed sensor generates an AC voltage.
Since the frequency of this AC voltage changes in direct propor-
tion to the speed of the rotors, the frequency is used by the ECU
to detect the speed of each wheel.

DTC No.DTC Detecting ConditionTrouble Area
31, 32, 33, 34
Detection of any of conditions 1 through 3:
1. At vehicle speed of 10 km/h (6 mph) or more, pulses are
not input for 5 sec.
2. Momentary interruption of the speed sensor signal oc-
curs at least 7 times in the time between switching the
ignition switch ON and switching it OFF
3. Abnormal fluctuation of speed sensor signals with the
vehicle speed 20 km/h (12 mph) or more

Right front, left front, right rear or left rear speed sensor

Open or short in each speed sensor circuit

ECU
HINT:

DTC 31 is for the right front speed sensor.

DTC 32 is for the left front speed sensor.

DTC 33 is for the right rear speed sensor.

DTC 34 is for the left rear speed sensor.
Fail safe function:
If trouble occurs in the speed sensor circuit, the ECU cuts off current to the ABS control (solenoid) relay and
prohibits ABS control.
DI983-01

R12890F15193
Right Front Speed Sensor
Left Front Speed Sensor
Right Rear Speed Sensor
Left Rear Speed Sensor2
1 2
2 2
1 1 1W B
R
G
9 10
A12FR+
FR-
FL+
FL-
RR+
RR-
RL+
RL- FSS
3 229
8 BRA12
A12
A12
A12
A13
A13
A13
A13
2 21
23ABS ECU
5 V
LG L
V
P
- DIAGNOSTICSANTI-LOCK BRAKE SYSTEM
DI-129
1996 TERCEL (RM440U)
WIRING DIAGRAM

R14676
21
R14669
1 2
DI-130
- DIAGNOSTICSANTI-LOCK BRAKE SYSTEM
1996 TERCEL (RM440U)
INSPECTION PROCEDURE
1 Check speed sensor.
Front:
PREPARATION:
Disconnect the speed sensor connector.
CHECK:
Measure the resistance between terminals 1 and 2 of the speed
sensor connector.
OK:
Resistance: 0.6 - 2.5 kW
CHECK:
Measure the resistance between terminals 1 and 2 of the speed
sensor connector and body ground.
OK:
Resistance: 1 MW or higher
Rear:
PREPARATION:
Disconnect the speed sensor connector.
CHECK:
Measure the resistance between terminals 1 and 2 of the speed
sensor connector.
OK:
Resistance: 0.8 - 1.8 kW
CHECK:
Measure the resistance between terminals 1 and 2 of the speed
sensor connector and body ground.
OK:
Resistance: 1 MW or higher
NG Replace speed sensor.
NOTICE:
Check the speed sensor signal last (See page DI-1 11).
OK
2 Check for open and short in harness and connector between each speed sensor
and ECU (See page IN-26).
NG Repair or replace harness or connector.
OK

R00948
BR4248
BR3795
OK NG
- DIAGNOSTICSANTI-LOCK BRAKE SYSTEM
DI-131
1996 TERCEL (RM440U)
3 Check sensor rotor and sensor installation.
Front:
PREPARATION:
Remove the drive shaft (See page SA-18).
CHECK:
Check the sensor rotor serrations.
OK:
No scratches or missing teeth.
CHECK:
Check the sensor tip.
OK:
No scratches or foreign objects on the sensor tip.
CHECK:
Check the front speed sensor installation.
OK:
The installation bolt is tightened properly and there is
no clearance between the sensor and steering
knuckle.
Rear:
PREPARATION:
Remove the drum (See page SA-39).
CHECK:
Check the sensor rotor serrations.
OK:
No scratches or missing teeth.
CHECK:
Check the sensor tip.
OK:
No scratches or foreign objects on the sensor tip.
CHECK:
Check the rear speed sensor installation.
OK:
The installation bolt is tightened properly and there is
no clearance between the sensor and rear axle carri-
er.
NG Replace speed sensor or rotor.
NOTICE:
Check the speed sensor signal last (See page DI-1 11).
OK
Check and replace ABS ECU.

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

BE6653R14671F06870
ON
GND
IG1
(-) (+)
F07208
GND (-) (+) LOCK
- DIAGNOSTICSANTI-LOCK BRAKE SYSTEM
DI-133
1996 TERCEL (RM440U)
INSPECTION PROCEDURE
1 Check battery positive voltage.
OK:
Voltage: 10 - 14 V
NG Check and repair charging system.
OK
2 Check voltage between terminals IG1 and GND of ABS ECU connector.
PREPARATION:
Disconnect the ABS ECU with connectors still connected.
CHECK:
(a) Turn the ignition switch ON.
(b) Measure the voltage between terminals IG1 and GND of
the ABS ECU connector.
OK:
Voltage: 10 - 14 V
NG Check and repair ABS ECU.
OK
3 Check continuity between terminal GND of ECU connector and body ground.
CHECK:
Measure the resistance between terminal GND of the ABS ECU
connector and body ground.
OK:
Resistance: 1 W or less
OK Repair or replace harness or connector.
NG

N02617
Driver Side J/B
ECU-IG
DI-134
- DIAGNOSTICSANTI-LOCK BRAKE SYSTEM
1996 TERCEL (RM440U)
4 Check ECU-IG fuse.
PREPARATION:
Remove the ECU-IG fuse from the driver side J/B.
CHECK:
Check the continuity of the ECU-IG fuse.
OK:
Continuity
NG Check for short in all harness and components
connected to ECU-IG fuse (See attached wiring
diagram).
OK
Check for open circuit in harness and con-
nector between ABS ECU and battery (See
page IN-26)