light LEXUS SC400 1991 Service Repair Manual

TR±11
WIRING DIAGRAM
DTC51Engine Malfunction Detection Circuit
CIRCUIT DESCRIPTION
If trouble (trouble which causes the malfunction indicator light to light\
up) occurs in the engine control system,
this circuit senses the trouble and prohibits TRAC control.
DTC No.DTC Detecting ConditionTrouble Area
51
Either of the following (1) and (2) continues formore
than 1 sec.:
(1) Engine speed: 500 RPM or more
(2) Voltage of TRAC ECU terminal TR5: 1 V or less
Short in TR5 circuit

ECM

TRAC ECU
DIAGNOSTIC CHARTDIAGNOSTIC CHART
BR±218±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
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TRAC OFF Indicator, TRAC Cut Switch Circuit
CIRCUIT DESCRIPTION
This is the TRAC control main switch. When the TRAC cut switch is pushed on,\
TRAC control goes off and
the TRAC OFF indicator lights up. This indicator is also used for warnings \
when the trouble occurs.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
BR±222±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
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NOYES
OKNG
OKNG
OKNG
OKNG
INSPECTION PROCEDURES
1Is diagnostic trouble code output?
Perform diagnostic trouble code check on page BR±184.
Repair circuit indicated by the code output.
2Check TRAC cut switch
C
OK
P1. Remove TRAC cut switch.
2. Disconnect TRAC cut switch connector.
Measure re sistance between terminals 1 and 2 of TRAC
cut switch when TRAC cut switch is on and off.
Replace TRAC cut switch.
3Check for open and short in harness and connector between terminal CSW of TRA\
C ECU and
TRAC cut switch and body ground (See page IN±33
).
Repair or replace harness or connector.
4Check TRAC OF indicator light.
See combination meter troubleshooting on page BE±191.
Repair or replace combination meter.
5Check for open and short in harness and connector between terminal WT of TRAC ECU \
and bat-
tery or TRAC solenoid relay (See page IN±33
).
Repair or replace harness or connector.
Check and replace TRAC ECU.
BR±224±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
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BR±150). BE±163
.
IN±33
).
WIRING DIAGRAM
TRAC Indicator Light Circuit
CIRCUIT DESCRIPTION
The TRAC indicator blinks during TRAC operation.
This indicator is also used for warnings when the trouble occurs and for disp\
laying diagnostic trouble codes.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)BR±225
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BR±160).
IN±33 ).
WIRING DIAGRAM
Tc Terminal Circuit
CIRCUIT DESCRIPTION
By connecting between terminals Tc and E1 of DLC1 or DLC2, the ECU displays the diagnostic trouble
code by blinking the TRAC indicator light.
DIAGNOSTIC CHARTDIAGNOSTIC CHART
BR±226±
BRAKE SYSTEM TRACTION CONTROL SYSTEM (TRAC)
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CHECK AND ADJUSTMENT
BR0EC±07
BRAKE PEDAL CHECK AND
ADJUSTMENT
1. CHECK THAT PEDAL HEIGHT IS CORRECT
Pedal height from asphalt sheet:150.4±160.4 mm (5.92±6.31 in.)
If the pedal height is incorrect, adjust it.
2. IF NECESSARY, ADJUST PEDAL HEIGHT
(a) Disconnect the connector from the stop light switch.
(b) Loosen the stop light switch lock nut and remove the stop light switch.
(c) Loosen the push rod lock nut.
(d) Adjust the pedal height by turning the pedal push rod.
(e) Tighten the push rod lock nut.
Torque: 25 N Vm (260 kgf Vcm, 19 ft Vlbf)
(f) Install the stop light switch and turn it until it lightly contacts
the pedal stopper.
(g) Turn the stop light switch back one turn.
(h) Check the clearance (A) between stop light switch and pedal.
Clearance:
0.5±2.4 mm (0.02±0.09 in.)
(i) Tighten the stop light switch lock nut.
(j) Connect the connector to the stop light switch.
(k) Check that the stop lights come on when the brake pedal isdepressed, and go off when the brake pedal is released.
(l) After adjusting the pedal height, check the pedal free±play.
HINT: If clearance (A) between the stop light switch and the
brake pedal stopper has been adjusted correctly, the pedal
freeplay will meet the specifications.
3. CHECK THAT PEDAL FREEPLAY IS CORRECT, AS SHOWN
(a) Stop the engine and depress the brake pedal several times until there is no more vacuum left in the booster.
(b) Push in the pedal by hand until the beginning of the second point of resistance is felt, then measure the distance, as
shown.
Pedal freeplay:
1±6 mm (0.04±0.24 in.)
If incorrect, check the stop light switch clearance. And if the
clearance is OK, then troubleshoot the brake system.
HINT: The freeplay to the first point of resistance is due to the
play between the clevis and pin. It is 1±3 mm (0.04±0.12 in.)
on the pedal.
±
BRAKE SYSTEM CHECK AND ADJUSTMENTBR±7
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4. CHECK THAT PEDAL RESERVE DISTANCE IS CORRECT,
AS SHOWN
Release the parking brake.
With the engine running, depress the pedal and measure the
pedal reserve distance, as shown.
Pedal reserve distance at 490 N (50 kgf, 110.2 lbf):
More than 89 mm (3.50 in.)
If the reserve distance is incorrect, troubleshoot the brake
system.
BRAKE BOOSTER OPERATIONAL TEST
BR03P±0B
1. OPERATING CHECK
(a) Depress the bake pedal several times with the engine off and
check that there is no change in the pedal reserve distance.
(b) Depress the brake pedal and start the engine. If the pedal goes down slightly, operation is normal.
2. AIR TIGHTNESS CHECK
(a) Start the engine and stop it after 1 or 2 minutes. Depress the brake pedal several times slowly. If the pedal goes down the
farthest the 1st time, but gradually rises after the 2nd or 3rd
time, the booster is air tight.
(b) Depress the brake pedal while the engine is running, and stop the engine with the pedal depressed. If there is no
change in the pedal reserve travel after holding the pedal for
30 seconds, the booster is air tight.
BRAKE SYSTEM BLEEDING
BR0ED±04
HINT: If any work is done on the brake system or if air in the
brake lines is suspected, bleed the system of air.
NOTICE: Do not let brake fluid remain on painted sur-
faces. Wash it off immediately.
1. REMOVE RESERVOIR CAP Turn the reservoir cap to the ªopenº side and remove it.
2. FILL RESERVOIR WITH BRAKE FLUID
Fluid: SAE J1703 or FMVSS NO.116DOT3
BR±8±
BRAKE SYSTEM CHECK AND ADJUSTMENT
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3. REMOVE RESERVOIRRemove the set screw and pull out the reservoir.
4. REMOVE 2 GROMMETS
5. PLACE CYLINDER IN VISE
6. w/ TRAC: REMOVE NO.1 PISTON STOPPER BOLT
Using a screwdriver, push the pistons in all the way and re-
move the No.1 piston stopper bolt and gasket.
HINT: Tape the screwdriver tip before use.
7. REMOVE NO.2 PISTON STOPPER BOLT Using a screwdriver, push the pistons in all the way and re-
move the No.2 piston stopper bolt and gasket.
8. REMOVE PISTONS
(a) Push in the piston with a screwdriver and remove the snap ring with snap ring pliers.
(b) Remove the No. 1 piston and spring by hand, pulling straight out, not at an angle.
NOTICE: If pulled out at an angle, there is a possibility that the
cylinder bore could be damaged.
(c) Place a rag and 2 wooden blocks on the work table and lightly
tap the cylinder flange against the block edges until the piston
drops out of the cylinder.
HINT: Make sure the distance (A) from the rag to the top of
the blocks is at least 100 mm (3.94 in.).
MASTER CYLINDER COMPONENTS
INSPECTION
BR03V±05
HINT: Clean the disassembled parts with compressed air.
1. INSPECT CYLINDER BORE FOR RUST OR SCORING
2. INSPECT CYLINDER FOR WEAR OR DAMAGE If necessary, clean or replace the cylinder.
±
BRAKE SYSTEM MASTER CYLINDERBR±15
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3. REMOVE BRAKE BOOSTER
(a) Remove the booster installation nuts.
(b) Remove the booster and gasket.
BRAKE BOOSTER INSTALLATION
BR03Z±08
1. INSTALL BRAKE BOOSTER
(a) Install the booster and gasket.
(b) Install and torque the booster installation nuts.
Torque: 12 NVm (125 kgf Vcm, 9 ft Vlbf)
(c) Insert the clevis pin into the clevis and brake pedal, and install
the clip to the clevis pin.
(d) Install the pedal return spring.
2. ADJUST LENGTH OF BOOSTER PUSH ROD
(a) Install the gasket on the master cylinder.
(b) Set the SST on the gasket, and lower the pin until its tip slightly touches the piston.
SST 09737±00010
(c) Turn the SST upside down, and set it on the booster. SST 09737±00010
(d) Measure the clearance between the booster push rod and
pin head (SST).
Clearance:
0 mm (0 in.)
(e) Adjust the booster push rod length until the push rod lightlytouches the pin head.
HINT: When adjusting the push rod, depress the brake pedal
enough so that the push rod sticks out.
3. INSTALL FOLLOWING PARTS: wVacuum hose
w Master cylinder
(See page BR±12)
w w/ TRAC:
TRAC pump assembly
(See page BR±162)
±
BRAKE SYSTEM BRAKE BOOSTERBR±19
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BR0EY±05
ECU TERMINALS STANDARD VALUE
w/o TRAC:
 


Symbols
(Terminals No.) 

STD Voltage (V)\
 
\

\
Condition
 


BAT
(A23±22) 
± 


GND
(A23±13) 


10±14\
 
\

\

Always
 IG
(A23±11) ± GND
(A23±2) 10±14\
 \
IG switch ON
 

SR
(A22±5) 

±
 

R±
(A22±4) 

8.3±14
\
 
\

\
IG switch ON, ABS warning light OFF
 

MR
(A22±11) 

±
 

R±
(A22±4) 

Below 1.0
\
 
\

\
IG switch ON
 


SFR
(A23±1) 

±
 


GND
(A23±2) 

10±14
\
 
\

\
IG switch ON, ABS warning light OFF
 


SFL
(A22±6) 
± 


GND
(A23±13) 

10±14\
 
\

\
IG switch ON, ABS warning light OFF
 


SRR
(A22±12) 
± 


GND
(A23±13) 

10±14\
 
\

\
IG switch ON, ABS warning light OFF
 AST
(A22±8) ± GND
(A23±13) 10±14\
 \
IG switch ON, ABS warning light OFF
 

WA
 

±
 

GND
 

Below 2.0
\
 
\

\
IG switch ON, ABS warning light ON
 
WA
(A23±10) 
±
 
GND
(A23±13) 10±14\
 \
IG switch ON, ABS warning light OFF
 PKB ± GND Below 1.5\
 \
IG switch ON, PKB switch ON
 
PKB
(A23±16) ± 
GND
(A23±13) 10±14\
 \
IG switch ON, PKB switch OFF
 STP 
±
 GND Below 1.5\
 \
Stop light switch OFF
 STP
(A23±7) ± GND
(A23±2) 8±14\
 \
Stop light switch ON
 

D/G
(A23±21) 

±
 

GND
(A23±13) 

10±14
\
 
\

\
IG switch ON, ABS warning light OFF
 


Tc
(A23±17) 

±
 


GND
(A23±13) 

10±14
\
 
\

\
IG switch ON
 


Ts
(A23±6) 
± 


GND
(A23±2) 

10±14\
 
\

\
IG switch ON
 


FR+
(A22±1) 
± 


FR±
(A22±7) 


AC generation\
 
\

\

IG switch ON
Slowly turn right front wheel
 FL+
(A22±3) ± FL±
(A22±10) AC generation\
 \
IG switch ON
Slowly turn left front wheel
 

RR+
(A23±19)
 

±
 

RR±
(A23±20)
 

AC generation
\
 
\

\
IG switch ON
Slowly turn right rear wheel
 

RL+
(A23±14) 

±
 

RL±
(A23±3) 

AC generation
\
 
\

\
IG switch ON
Slowly turn left rear wheel
±
BRAKE SYSTEM ANTI±LOCK BRAKE SYSTEM (ABS)BR±59
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