ANTI-LOCK BRAKE SYSTEM
1990 Nissan 240SX
1989-91 BRAKES
Nissan Anti-Lock Brake System
NISSAN; MAXIMA, STANZA, 240SX & 300ZX
DESCRIPTION
Anti-Lock Brake System (ABS) is designed to allow driver to
maintain steering control during heavy braking. ABS system consists of
an Electronic Control Unit (ECU), actuator (electro-hydraulic unit),
warning lights, wheel speed sensors, wiring and hydraulic lines. See
Figs. 1-4.
Actuator (electro-hydraulic unit) consists of a pump motor,
accumulator, solenoid valves for each channel, actuator relay, pump
motor relay, check valves and reservoirs. Maxima, Stanza and 300ZX use
a 4-channel system, and 240SX uses a 3-channel system. ECU has self-
diagnostic capability to alert driver in the event of a system
malfunction. An LED located on the ABS Electronic Control Unit (ECU)
will flash (indicating trouble codes) when warning light is
illuminated.
NOTE: For more information on brake system, see BRAKE SYSTEM
article in the BRAKES Section.
Fig. 1: Locating ABS Components (Maxima)
Courtesy of Nissan Motor Co., U.S.A.
Fig. 2: Locating ABS Components (Stanza)
Courtesy of Nissan Motor Co., U.S.A.
Fig. 3: Locating ABS Components (240SX)
Courtesy of Nissan Motor Co., U.S.A.
Fig. 4: Locating ABS Components (300ZX)
Courtesy of Nissan Motor Co., U.S.A.
OPERATION
As vehicle is moving, speed sensors send an AC signal to ECU.
ECU monitors the stoplight switch to determine when driver presses
brake pedal. When brake pedal is pressed, ECU monitors signals from
each speed sensor to determine rate of deceleration.
If rate of deceleration from any speed sensor reaches a
preprogrammed rate, ECU activates solenoid valves inside actuator.
Solenoid valves are cycled to apply, release or maintain hydraulic
pressure to each wheel in any combination.
Regulating hydraulic pressure to each circuit prevents wheel
lock-up. When driver releases brake pedal, ECU deactivates solenoid
valves, placing brake system back into a conventional mode until ABS
is again needed.
If a fault is detected by ECU, an ANTI-LOCK light located on
the instrument panel illuminates. Although ECU deactivates ABS when a
fault is detected, conventional brake system is not be affected.
WARNING: Failure to depressurize ABS could lead to physical injury.
ANTI-LOCK BRAKE SAFETY PRECAUTIONS
* NEVER open a bleeder valve or loosen a hydraulic line while ABS
is pressurized.
* NEVER disconnect or reconnect any electrical connectors while
ignition is on. Damage to ABS control unit may result.
* DO NOT attempt to bleed hydraulic system without first referring
to the appropriate article.
* Only use specially designed brake hoses/lines on ABS-equipped
vehicles.
* DO NOT tap on speed sensor components (sensor, sensor rings).
Speed rings must be pressed, NOT hammered into hubs. Striking
these components can cause demagnetization or a loss of
polarization, affecting the accuracy of the speed signal
returning to the ABS control unit.
* DO NOT mix tire sizes. Increasing the width, as long as tires
remain close to the original diameter, is acceptable. Rolling
diameter must be identical for all 4 tires. Some manufacturers
recommend tires of the same brand, style and type. Failure to
follow this precaution may cause inaccurate wheel speed readings.
* DO NOT contaminate speed sensor components with grease. Only use
recommended anti-corrosion coating.
* When speed sensor components have been removed, ALWAYS check
sensor-to-ring air gaps when applicable. These specifications can
be found in each appropriate article.
* ONLY use recommended brake fluids. DO NOT use silicone brake
fluids in an ABS-equipped vehicle.
* When installing transmitting devices (CB’s, telephones, etc.) on
ABS-equipped vehicles, DO NOT locate the antenna near the ABS
control unit (or any control unit).
* Disconnect all on-board computers, when using electric welding
equipment.
* DO NOT expose the ABS control unit to prolonged periods of high
heat (185 F/85 C for 2 hours is generally considered a maximum
limit).
BLEEDING BRAKE SYSTEM
To bleed system, unplug electrical connectors from actuator.
Bleed brake system the same as a conventional system using appropriate
bleeding sequence. See HYDRAULIC LINE BLEEDING SEQUENCE TABLE. After
bleeding brakes, bleed front side of actuator and then rear side of
actuator. Use DOT 3 brake fluid only.
HYDRAULIC LINE BLEEDING SEQUENCE TABLE
Application Sequence
Maxima & Stanza ................. Left Rear
Right Front
Right Rear
Left Front
240SX & 300ZX ................... Left Rear
Right Rear
Right Front
Left Front
ADJUSTMENTS
BRAKE PEDAL HEIGHT & FREE PLAY
1) Measure pedal height from pressure face of pedal pad to
floor pan insulator, without carpet. See BRAKE PEDAL HEIGHT
SPECIFICATIONS TABLE.
2) To adjust to pedal height, loosen brake booster input rod
lock nut, and rotate input rod to attain proper height. Tighten lock
nut and adjust stoplight switch. Ensure pedal free play is .04-.12"
(1-3 mm).
BRAKE PEDAL HEIGHT SPECIFICATIONS TABLE
Application Pedal Height - In. (mm)
Maxima & Stanza
Auto. Trans. .................. 6.65-7.05 (169-179)
Man. Trans. ................... 6.26-6.65 (159-169)
240SX
Auto. Trans. .................. 7.32-7.72 (186-196)
Man. Trans. ................... 6.97-7.36 (177-187)
300ZX
Auto. Trans. .................. 7.68-8.07 (195-205)
Man. Trans. ................... 7.32-7.72 (186-196)
LOAD-SENSING PROPORTIONING VALVE
NOTE: If pressure cannot be adjusted to within specifications,
replace entire valve assembly as a unit.
Pressure Adjustment (Maxima)
1) With one person inside vehicle, set rear axle load to 1323
lbs. (595 kg) of weight in trunk. Attach 2 pressure gauges, one to
front and one to rear brake bleeder. Bleed air from front and rear
bleeders.
brake pedal until front brake pressure reading is
2) Depress
711 psi (50 kg/cm ). Check rear brake pressure. See LSPV PRESSURE
SPECIFICATIONS TABLE. Depress brake pedal until front brake pressure
reading is 1422 psi (100 kg/cm ). Check rear brake pressure. See LSPV
PRESSURE SPECIFICATIONS TABLE.
CAUTION: Check rear brake pressure 2 seconds after front brake
pressure reaches specified value.
LSPV PRESSURE SPECIFICATIONS TABLE
Front Brake Pressure Rear Brake Pressure
Application psi (kg/cm ) psi (kg/cm )
Maxima ................ 711 (50) ............ 555-697 (39-49)
Maxima ............... 1422 (100) ........... 739-939 (52-66)
3) If readings are not correct, adjust sensor spring length
by turning adjusting bolt. See Fig. 5. Repeat test and recheck
pressure. If pressure cannot be adjusted to specification, replace
LSPV.
Fig. 5: Adjusting Load-Sensing Proportioning Valve (Maxima)
Courtesy of Nissan Motor Co., U.S.A.
PARKING BRAKE
1) Remove parking brake lever cover. Raise and support rear
of vehicle. Pull up on parking brake lever using 44 lbs. (20 kg) of
force. Rear wheels should lock at appropriate lever stroke. See
PARKING BRAKE LEVER STROKE SPECIFICATIONS TABLE.
2) Adjust parking brake using adjusting nut beside or below
parking brake lever. After releasing lever, ensure rear wheels rotate
freely. No slack should be present at rear cables.
PARKING BRAKE LEVER STROKE SPECIFICATIONS TABLE
Application Notches
Maxima & Stanza ................................ 9-11
240SX ........................................... 6-8
300ZX ........................................... 6-7
POWER BRAKE UNIT OUTPUT ROD
1) Attach a hand-held vacuum pump to power brake unit supply
port. Apply 20 in. Hg vacuum to power brake unit. Measure length of
output rod extending from power brake unit housing. See Fig. 6.
2) Output rod length should be .40-.41" (10.3-10.5 mm).
Adjust output rod length, if necessary. See Fig. 6. If adjustment
cannot be obtained, replace power brake unit.
Fig. 6: Measuring Length of Output Rod Extending from Power Brake
Unit Housing. Courtesy of Nissan Motor Co., U.S.A.
STOPLIGHT SWITCH & AUTOMATIC SPEED CONTROL DEVICE SWITCH
Clearance Adjustment
1) Both switches are located below dash panel at brake pedal
bracket. Adjust brake pedal height. See BRAKE PEDAL HEIGHT & FREE PLAY
under ADJUSTMENTS.
2) Check clearance and position of switches. Clearance
between brake pedal stopper rubber and threaded end of switch should
be .01-.04" (.3-1 mm). To adjust, loosen lock nut and turn switch
body. After adjustment, tighten lock nut.
TROUBLE SHOOTING
SYMPTOMS
Pedal Vibration & Noise - See Fig. 8.
Long Stopping Distance - See Fig. 9.
Abnormal Pedal Action - See Fig. 10.
ABS Does Not Work - See Fig. 11.
ABS Works But ANTI-LOCK Light Activates - See Fig. 12.
ABS Works Too Frequently - See Fig. 13, 14, 15, or 16.
ANTI-LOCK Light On, LED Does Not Flash - See Fig. 17.
DIAGNOSIS & TESTING
NOTE: Actuator testing requires the use of Tester (KV999P1000) and
Adapter (KV999P1010).
PRE-INSPECTION
1) To correctly diagnose system, inspect all brake components
for wear or damage. Ensure hydraulic system is full and no leaks
exist. Ensure brake booster is functioning properly. Check air gap at
each speed sensor. See WHEEL SPEED SENSOR AIR GAP TABLE.
2) On 240SX, measure rear speed sensor air gap by inserting
feeler gauge between sensor mating face on differential to exciter
ring on pinion flange. Measure speed sensor pole piece from sensor
mating face to pole piece tip. Subtract sensor measurement from
differential measurement to obtain air gap.
3) On all models, if air gap exceeds specification, replace
speed sensor, pinion flange (240SX) or wheel hub assembly. Inspect
rotor teeth. Replace rotor (and companion flange, if necessary) if
teeth are damaged. Go to PRELIMINARY CHECK.
WHEEL SPEED SENSOR AIR GAP TABLE
Application In. (mm)
Maxima & Stanza
Front & Rear ................. .008-.039 (.20-1.00)
240SX
Front ......................... .011-.030 (.28-.75)
Rear .......................... .014-.025 (.35-.63)
300ZX
Front ......................... .009-.028 (.23-.71)
Rear .......................... .002-.037 (.05-.94)
PRELIMINARY CHECK
1) After completing PRE-INSPECTION, check resistance of each
wheel speed sensor. If resistance is not 800-1200 ohms, replace
sensor, and retest. If resistance is okay, turn ignition on and check
ANTI-LOCK warning light operation. Light should illuminate when
ignition is turned on. If light does not come on, check fuse, wiring
and bulb for fault.
2) If warning light comes on, start engine and observe ANTI-
LOCK warning light. Warning light should go out when engine is
started. If warning light stays on after starting engine, leave
ignition on and go to RETRIEVING TROUBLE CODES. If light goes off
after starting engine, go to next step.
3) Drive vehicle for at least one minute at a minimum speed
of 19 MPH. If warning light stays off during road test, no fault is
present in ABS. If light comes on and stays on during road test, leave
ignition on and go to RETRIEVING TROUBLE CODES. Ensure shielding wire
ground for each sensor and ground for pump motors have continuity to
ground.
RETRIEVING TROUBLE CODES
NOTE: ECU can store (and indicate with LED) only one trouble code
at a time. After indicated code circuit is repaired, road
test vehicle and recheck codes for additional indicated
faults.
If ANTI-LOCK light on instrument panel is on, a trouble code
has been set. DO NOT turn ignition off. To retrieve trouble code,
locate ECU. See Figs. 1-4. Count number of times LED on ECU flashes.
See Fig. 7. See appropriate ABS TROUBLE CODES TABLE and go to
appropriate trouble shooting chart to properly diagnose problem.
Fig. 7: Identifying Codes by Counting LED Flashes
Courtesy of Nissan Motor Co., U.S.A.
ABS TROUBLE CODES TABLE (MAXIMA & STANZA)
Trouble Code Circuit Go To
1 .................... L/F Actuator Solenoid ........ Fig. 18
2 .................... R/F Actuator Solenoid ........ Fig. 18
3 .................... R/R Actuator Solenoid ........ Fig. 18
4 .................... L/R Actuator Solenoid ........ Fig. 18
5 .................... L/F Wheel Speed Sensor ....... Fig. 20
6 .................... R/F Wheel Speed Sensor ....... Fig. 20
7 .................... R/R Wheel Speed Sensor ....... Fig. 20
8 .................... L/R Wheel Speed Sensor ....... Fig. 20
9 ......................... Pump Motor .............. Fig. 23
10 ...................... Solenoid Valve ......... Fig. 26/27
16 Or Continuous .............. ECU ..................... ( 1)
(1) - Replace ABS control unit (ECU).
ABS TROUBLE CODES TABLE (240SX)
Trouble Code Circuit Go To
1 .................... L/F Actuator Solenoid ........ Fig. 19
2 .................... R/F Actuator Solenoid ........ Fig. 19
3 Or 4 .............. Rear Actuator Solenoid ........ Fig. 19
5 ................... L/F Wheel Speed Sensor ........ Fig. 21
6 ................... R/F Wheel Speed Sensor ........ Fig. 21
7 Or 8 .............. R/R Wheel Speed Sensor ........ Fig. 21
9 ......................... Pump Motor .............. Fig. 24
10 ...................... Solenoid Valve ............ Fig. 28
16 Or Continuous .............. ECU ..................... ( 1)
(1) - Replace ABS control unit (ECU).
ABS TROUBLE CODES TABLE (300ZX)
Code Circuit Go To
1 ...................... L/F Actuator Solenoid ...... Fig. 19
2 ...................... R/F Actuator Solenoid ...... Fig. 19
3 Or 4 ................ Rear Actuator Solenoid ...... Fig. 19
5 ...................... L/F Speed Sensor ........... Fig. 22
6 ...................... R/F Speed Sensor ........... Fig. 22
7 ...................... R/R Speed Sensor ........... Fig. 22
8 ...................... L/R Speed Sensor ........... Fig. 22
9 ................ Actuator Motor, Motor Relay ...... Fig. 25
10 .................... Actuator Sol. Relay ......... Fig. 29
16 ............................ ECU .................... ( 1)
(1) - Replace ABS control unit (ECU).
REMOVAL & INSTALLATION
ACTUATOR
Removal & Installation
Disconnect negative battery cable. Disconnect electrical
connectors and hydraulic lines at actuator. Remove mounting bolts and
actuator. To install, reverse removal procedure. Bleed brake system.
See BLEEDING BRAKE SYSTEM.
ELECTRONIC CONTROL UNIT (ECU)
CAUTION: Before servicing ECU, ground yourself and ground the work
area to discharge stored electricity. As little as a
30-volt charge created by static electricity can cause a
total or degrading failure in ECU or other electronic
components containing integrated circuits.
Removal & Installation
Disconnect negative battery cable. Locate ECU. See Figs. 1-4.
Disconnect electrical connector and remove ECU. To install, reverse
removal procedure.
WHEEL SPEED SENSORS
Removal & Installation
To remove front sensor or rear wheel speed sensor, remove
sensor retaining bolt and sensor. To install, reverse removal
procedure. Tighten sensor mounting bolts to specification. See TORQUE
SPECIFICATIONS TABLE.
WHEEL SPEED SENSOR ROTORS
Removal & Installation
1) To remove front wheel speed sensor rotor, remove steering
hub and axle assembly. To remove rear wheel speed sensor rotor on
Maxima and Stanza, remove rear wheel hub bearing.
2) To remove rear speed sensor rotor on 240SX, remove drive
shaft and drive pinion flange. To remove rear speed sensor rotor on
300ZX, remove with differential side flange after removing axle shaft.
To install components, reverse removal procedure.
DIAGNOSTIC TROUBLE SHOOTING CHARTS
Fig. 8: No Code - Pedal Vibration & Noise Trouble Shooting Chart
Courtesy of Nissan Motor Co., U.S.A.
Fig. 9: No Code - Long Stopping Distance Trouble Shooting Chart
Courtesy of Nissan Motor Co., U.S.A.
Fig. 10: No Code - Abnormal Pedal Action Trouble Shooting Chart
Courtesy of Nissan Motor Co., U.S.A.
Fig. 11: ABS Does Not Work Trouble Shooting Chart
Courtesy of Nissan Motor Co., U.S.A.
Fig. 12: No-Code - ABS Works, But ANTI-LOCK Light Activates Trouble
Shooting Chart. Courtesy of Nissan Motor Co., U.S.A.
Fig. 13: No Code - ABS Works Too Frequently Trouble Shooting
Chart Maxima. Courtesy of Nissan Motor Co., U.S.A.
Fig. 14: No Code - ABS Works Too Frequently Trouble Shooting Chart
Stanza. Courtesy of Nissan Motor Co., U.S.A.
Fig. 15: No Code - ABS Works Too Frequently Trouble Shooting Chart
240SX. Courtesy of Nissan Motor Co., U.S.A.
Fig. 16: No Code - ABS Works Too Frequently Trouble Shooting Chart
300ZX. Courtesy of Nissan Motor Co., U.S.A.
Fig. 17: No Code - ANTI-LOCK Light On, LED Does Not Flash Trouble
Shooting Chart. Courtesy of Nissan Motor Co., U.S.A.
Fig. 18: Codes 1-4 - Actuator Solenoid Circuit Trouble Shooting
Chart Maxima & Stanza. Courtesy of Nissan Motor Co., U.S.A.
Fig. 19: Codes 1-4 - Actuator Solenoid Circuit Trouble Shooting
Chart 240SX & 300ZX. Courtesy of Nissan Motor Co., U.S.A.
Fig. 20: Codes 5-8 - Wheel Speed Sensor Circuit Trouble Shooting
Chart Maxima & Stanza. Courtesy of Nissan Motor Co., U.S.A.
Fig. 21: Codes 5-8 - Wheel Speed Sensor Circuit Trouble
Shooting Chart 240SX. Courtesy of Nissan Motor Co., U.S.A.
Fig. 22: Codes 5-8 - Wheel Speed Sensor Circuit Trouble Shooting
Chart 300ZX. Courtesy of Nissan Motor Co., U.S.A.
Fig. 23: Code 9 - Pump Motor Circuit Trouble Shooting Chart
Maxima & Stanza. Courtesy of Nissan Motor Co., U.S.A.
Fig. 24: Code 9 - Pump Motor Circuit Trouble Shooting Chart (240SX)
Courtesy of Nissan Motor Co., U.S.A.
Fig. 25: Code 9 - Pump Motor Circuit Trouble Shooting Chart (300ZX)
Courtesy of Nissan Motor Co., U.S.A.
Fig. 26: Code 10 - Solenoid Valve Circuit Trouble Shooting
Chart Maxima. Courtesy of Nissan Motor Co., U.S.A.
Fig. 27: Code 10 - Solenoid Valve Circuit Trouble Shooting Chart
Stanza. Courtesy of Nissan Motor Co., U.S.A.
Fig. 28: Code 10 - Solenoid Valve Circuit Trouble Shooting Chart
240SX. Courtesy of Nissan Motor Co., U.S.A.
Fig. 29: Code 10 - Solenoid Valve Circuit Trouble Shooting Chart
300ZX. Courtesy of Nissan Motor Co., U.S.A.
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS TABLE
Application Ft. Lbs. (N.m)
Hydraulic Brake Lines At Actuator ..... 14-18 (19-24)
Wheel Lug Nuts ....................... 72-87 (98-118)
Wheel Speed Sensor Mounting Bolt
Maxima & Stanza ..................... 13-17 (18-23)
240SX & 300ZX ....................... 13-20 (18-27)
WIRING DIAGRAMS
For additional wiring diagrams, see appropriate chassis
wiring in WIRING DIAGRAMS.
Fig. 30: ABS Wiring Diagram (1989-90 Maxima)
Fig. 31: Anti-Lock Brake (ABS) Wiring Diagram (1990 Stanza)
Fig. 32: Anti-Lock Brake (ABS) Wiring Diagram (Stanza)
Fig. 33: Anti-Lock Brake (ABS) Wiring Diagram (1989 240SX)
Fig. 34: Anti-Lock Brake (ABS) Wiring Diagram (300ZX)
