1991 LEXUS SC400 light

OKNG
OKNG
INSPECTION PROCEDURE
1Check ABS warning light.
See Combination Meter Troubleshooting on page BE±159.
Replace bulb or combination meter assembly.
2Check ABS solenoid relay.
C
OK
P
OK
C
Remove solenoid relay from R/B No. 6.
Check continuity between each terminal of ABS sole-
noid relay shown below.
1. Apply battery voltage between terminals 4 and 6.
2. Check continuity between each terminal of ABS so-
lenoid relay shown below.
Replace ABS solenoid relay.
Repair or replace and check for open in harness and connector between ch\
eck connector and ABS
solenoid relay and body ground (See page IN±33).
BR±146±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
WhereEverybodyKnowsYourName

NOYES
YESNO
OKNG
INSPECTION PROCEDURE
3Is diagnosis trouble code output?
Perform diagnostic trouble code check on page BR±76.
Repair circuit indicated by the code output.
4Does ABS warning light go off if short pin is removed?
Check for short in harness and connector between warn-
ing light and data link connector 1 and ECU (See page
IN±33 ).
5Check ABS solenoid relay (See step No. ).
Replace ABS solenoid relay.
Repair or replace and check for short in harness
and connector between data link connector 1 and
ABS solenoid relay (See page IN±33).
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±147
WhereEverybodyKnowsYourName

IN±33).
WIRING DIAGRAM
Tc Terminal Circuit
CIRCUIT DESCRIPTION
Connecting between terminals Tc and E1 of the DLC1 or the DLC2 causes the ECU to display the diagnos-
tic trouble code by flashing the ABS warning light.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
BR±148±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)
WhereEverybodyKnowsYourName

NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminals Tc and E1 of DLC2 or DLC1.
C
OK
PTurn ignition switch ON.
Measure voltage between terminals Tc and E1 of DLC2
or DLC1.
Voltage: 10 ± 14 V
If ABS warning light does not blink even after Tc and E1
are connected,t he ECU may be defective.
2Check for open and short in harness and connector between ABS (& TRAC) ECU \
and DLC2 or
DLC1, DLC2 or DLC1 and body ground (See page IN±33).
Repair or replace harness or connector.
Check and replace ABS (& TRAC) ECU.
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±149
WhereEverybodyKnowsYourName

NGOK
OKNG
INSPECTION PROCEDURE
1Check voltage between terminal Ts and E1 of data link connector 1.
C
OK
PTurn ignition switch ON.
Measure voltage between terminals Ts and E1 of DLC1.
Voltage: 10 ± 14 V
If ABS warning light does not blink even after Ts and E1
are connected, the ECU may be defective.
2Check for open and short in harness and connector between ABS (& TRAC) ECU and D\
LC1,
DLC1 and body ground (See page IN±33).
Repair or replace harness or connector.
Check and replace ABS (& TRAC) ECU.
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±151
WhereEverybodyKnowsYourName

ECU TERMINALS STANDARD VALUE
ABS & TRAC ECU:
BR0F8±03
 Symbols
(Terminals No.) STD Voltage (V)\
 \
Condition
 

BAT
(A25±21)
 

±
 

GND
(A25±22)
 

10±14
\
 
\

\
Always
 

IG
(A24±24) 

±
 

GND
(A25±22) 

10±14
\
 
\

\
IG switch ON
 

SR
(A24±22) 

±
 

R±
(A24±25) 

8.3±14
\
 
\

\
IG switch ON, ABS warning light OFF
 


MR
(A25±16) 

± 


R±
(A24±25) 

Below 1.0\
 
\

\
IG switch ON
 


TSR
(A24±1) 

± 


R±
(A24±25) 

8.3±14\
 
\

\
IG switch ON, TRAC indicator light OFF
 


TMR
(A24±9) 


± 


R±
(A24±25) 


Below 1.0\
 
\

\

IG switch ON
 SFR
(A25±1) ± GND
(A25±2) 10±14\
 \
IG switch ON, ABS warning light OFF
 

SFL
(A24±13) 

±
 

GND
(A25±22) 

10±14
\
 
\

\
IG switch ON, ABS warning light OFF
 

SRR
(A24±26) 

±
 

GND
(A25±22) 

10±14
\
 
\

\
IG switch ON, ABS warning light OFF
 


SRL
(A25±12) 

±
 


GND
(A25±13) 

10±14
\
 
\

\
IG switch ON, ABS warning light OFF
 


AST
(A24±8) 

± 


GND
(A25±22) 

10±14\
 
\

\
IG switch ON, ABS warning light OFF
 


SAC
(A24±12) 


± 


GND
(A25±22) 


10±14\
 
\

\

IG switch ON, TRAC indicator light OFF
 SMC
(A24±2) ± GND
(A25±22) 10±14\
 \
IG switch ON, TRAC indicator light OFF
 

SRC
(A24±15)
 

±
 

GND
(A25±22
 

10±14
\
 
\

\
IG switch ON, TRAC indicator light OFF
 

PR
(A24±10) 

±
 

E2
(A24±20) 

5±7
\
 
\

\
IG switch ON
 


VC
(A24±19) 

±
 


E2
(A24±20) 

4±6
\
 
\

\
IG switch ON
 ALT 
±
 GND Below 1.0\
 \
IG switch ON
 ALT
(A25±8) ± GND
(A25±22) 10±14\
 \
Idling
 
WA
 
±
 
GND
 Below 2.0\
 \
IG switch ON, ABS warning light ON WA
(A25±9) ± GND
(A25±22) 10±14\
 \
IG switch ON, ABS warning light OFF 


PKB
 


±
 


GND
 

Below 1.5
\
 
\

\
IG switch ON, PKB switch ON,
Fluid in M/C reservoir above MIN level
 


PKB
(A25±17) 


± 


GND
(A25±22) 

10±14
\
 
\

\
IG switch ON, PKB switch OFF,
Fluid in M/C reservoir above MIN level
BR±158±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
WhereEverybodyKnowsYourName

 



Symbols
(Terminals No.) 


STD Voltage (V)\
 
\

\

Condition
 LBL
(A25±6)  ± GND
(A25±22) 10±14\
 \
IG switch ON
Fluid in M/C reservoir tank above MIN level.
 

STP
 

±
 

GND
 

Below 1.5\
 
\

\
Stop light switch OFF 


STP
(A25±10) 
± 


GND
(A25±22) 

8±14
\
 
\

\
Stop light switch ON
 D/G
(A25±20) ± GND
(A25±22) 10±14\
 \
IG switch ON, ABS warning light OFF
 

Tc
(A26±3)
 

±
 

GND
(A25±22)
 

10±14
\
 
\

\
IG switch ON
 

Ts
(A26±1) 

±
 

GND
(A25±22) 

10±14
\
 
\

\
IG switch ON
 P 
±
 GND 10±14\
 \
IG switch ON, Shift position in ªPº position P
(A26±10) ± GND
(A25±22) Below 1.5\
 \
IG switch ON, Other shift position in ªPº position 

N
 

±
 

GND
 

10±14\
 
\

\
IG switch ON, Shift position in ªNº position
 
N
(A26±5) 
±
 
GND
(A25±22) Below 1.5\
 \
IG switch ON, Other shift position in ªNº position
 

FR+
(A24±17) ± 

FR±
(A24±4) 

AC generation\
 
\

IG switch ON
Slowly turn right front wheel.
 

FL+
(A24±5)
 

±
 

FL±
(A24±18)
 

AC generation
\
 
\

\
IG switch ON
Slowly turn left front wheel.
 

RR+
(A25±14) 

±
 

RR±
(A25±3) 

AC generation
\
 
\

\
IG switch ON
Slowly turn right rear wheel.
 

RL+
(A25±4) 

±
 

RL±
(A25±15) 

AC generation
\
 
\

\
IG switch ON
Slowly turn left rear wheel.
 


FRO
(A26±15) 
± 


GND
(A25±22) 

Pulse generation\
 
\

\

IG switch ON
Slowly turn right front wheel.
 


FLO
(A26±6) 
± 


GND
(A25±22) 

Pulse generation\
 
\

\

IG switch ON
Slowly turn left front wheel.
 


RRO
(A26±13) 
± 


GND
(A25±22) 


Pulse generation\
 
\

\

IG switch ON
Slowly turn right rear wheel.
 RLO
(A26±4) ± GND
(A25±22) Pulse generation\
 \
IG switch ON
Slowly turn left rear wheel.
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±159
WhereEverybodyKnowsYourName

 



Symbols
(Terminals No.) 


STD Voltage (V)\
 
\

\

Condition
 IND
(T13±11) ± GND
(T14±14) 10±14\
 \
IG switch ON, TRAC indicator light OFF
 

WT
 

±
 

GND
 

Below 2.0\
 
\

\
IG switch ON, TRAC OFF indicator light ON 


WT
(T13±14) 
± 


GND
(T14±14) 

10±14
\
 
\

\
IG switch ON, TRAC OFF indicator light OFF
 STP ± GND Below 1.5\
 \
Stop light switch OFF
 
STP
(T13±2) ± 
GND
(T14±14) 8±14\
 \
Stop light switch ON
 P 
±
 GND 10±14\
 \
IG switch ON, Shift position in ªPº position
 
P
(T13±7) ± 
GND
(T14±14) Below 1.5\
 \
IG switch ON, Other shift position in ªPº position
 N 
±
 GND 10±14\
 \
IG switch ON, Shift position in ªNº position
 N
(T13±16) ± GND
(T14±14) Below 1.5\
 \
IG switch ON, Other shift position in ªNº position 

Tc
(T13±6) 

±
 

GND
(T14±14) 

10±14
\
 
\

\
IG switch ON
 

FRO
(T13±10) 

±
 

GND
(T14±14) 

Pulse generation
\
 
\

\
IG switch ON
Slowly turn right front wheel
 


FLO
(T13±3) 
± 


GND
(T14±14) 

Pulse generation\
 
\

\

IG switch ON
Slowly turn left front wheel
 


RRO
(T13±12) 
± 


GND
(T14±14) 

Pulse generation\
 
\

\

IG switch ON
Slowly turn right rear wheel
 


RLO
(T13±5) 
± 


GND
(T14±14) 


Pulse generation\
 
\

\

IG switch ON
Slowly turn left rear wheel
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±161
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