traction control INFINITI FX35 2005 Service Manual

BRC-8
[VDC/TCS/ABS]
SYSTEM DESCRIPTION
Revision: 2005 July 2005 FX
SYSTEM DESCRIPTIONPFP:00000
System DiagramAFS001SB
VDC FunctionAFS001SC

In addition to the TCS/ABS function, the driver steering amount and brake operation amount are detected
from steering angle sensor and pressure sensor, and the vehicle's driving status (amount of under steer-
ing / over steering) is determined from information from G sensor, wheel sensor, etc., and this information
is used to improve vehicle stability by controlling the braking and engine power to all four wheels.

SLIP indicator lamp flashes to inform the driver of VDC operation.

During VDC operation, body and brake pedal lightly vibrate and mechanical noises may be heard. This is
normal.

ABS warning lamp, VDC OFF indicator lamp, and SLIP indicator lamp might turn on when vehicle is sub-
ject to strong shaking or large vibration, such as when vehicle is on a turn table, a ship or a steep slope
such as bank while engine is running. In this case, restart engine on a normal road, and if ABS warning
lamp, VDC OFF indicator lamp, and SLIP indicator lamp turn off, there is no malfunction.
TCS FunctionAFS001SD

The wheel spin of the drive wheels is detected by ABS actuator and electric unit (control unit) from the
wheel speed signals from four wheels, so if wheel spin occurs, drive wheel right and left brake fluid pres-
sure control and engine fuel cut are performed while throttle value is restricted to reduce the engine
torque and decrease the amount of wheel spin. In addition, the degree throttle is opened is controlled to
achieve the optimum engine torque.

Depending on road circumstances, the driver may have a sluggish feel. This is normal, because the opti-
mum traction has the highest priority under TCS operation.

TCS may be activated any time vehicle suddenly accelerates, suddenly down/upshifts, or is driven on a
road with a varying surface friction coefficient.

During TCS operation, it informs a driver of system operation by flashing SLIP indicator lamp.
ABS FunctionAFS001SE

The anti-lock brake system is a function that detects wheel revolution while braking, and it improves han-
dling stability during sudden braking by electrically preventing 4 wheel lock. Maneuverability is also
improved for avoiding obstacles.

If the electrical system malfunctions, then the fail-safe function starts, the ABS becomes inoperative, and
ABS warning lamp turns on.

Electrical system diagnosis by CONSULT-II is available.

During ABS operation, brake pedal lightly vibrates and a mechanical noise may be heard. This is normal.
SFIA1160E

TROUBLE DIAGNOSIS BRC-35
[VDC/TCS/ABS]
C
D E
G H
I
J
K L
M A
B
BRC
Revision: 2005 July 2005 FX
For Fast and Accurate DiagnosisAFS001SR
PRECAUTIONS FOR DIAGNOSIS

Before performing diagnosis, always read precautions. Refer to BRC-12, "How to Proceed with Diagno-
sis" .

If ABS actuator and electric unit (control unit), steering angle sensor, steering system parts or suspension
system parts have been replaced, or if alignment has been adjusted, be sure to adjust neutral position of
steering angle sensor before driving. Refer to BRC-6, "
Adjustment of Steering Angle Sensor Neutral Posi-
tion" .

After diagnosis is finished, be sure to erase memory. Refer to BRC-27, "SELF-DIAGNOSIS" .

When checking continuity and voltage between units, be sure to check for disconnection, looseness,
bend, or collapse of connector terminals. If any malfunction is found, repair or replace connector termi-
nals.

For intermittent symptoms, possible cause is malfunction in harness, harness connector, or terminals.
Move harness, harness connector, and terminals to check for poor connections.

If a circuit tester is used for the check, be careful not to forcibly extend any connector terminal.

To use CONSULT-II to perform self-diagnosis of ABS actuator and electric unit (control unit), active tests,
or work support, first stop work, then connect CONSULT-II and select “ABS”.

While self-diagnostic results of CONSULT-II shows malfunction, if CONSULT-II active test is performed,
an engine system error may be indicated. In this case, start engine to resume the normal screen.

VDC/TCS/ABS system electronically controls brake operation and engine output. The following symptoms
may be caused by normal operations:
Symptom Symptom description Result
Motor operation noise This is noise of motor inside ABS actuator and electric unit (control unit).
Slight noise may occur during VDC, TCS, and ABS operation.
Normal
When the vehicle speed goes over 20 km/h (12.5 MPH), motor and
valves operating noise may be heard. It happens only once after IGN
(ignition) is ON. This is a normal status of the system operation check.
System operation check
noise When engine starts, slight “click” noise may be heard from engine room.
This is normal and is part of system operation check. Normal
VDC/TCS operation
(SLIP indicator lamp blink-
ing) TCS may activate momentarily if wheel speed changes when driving
over location where friction coefficient varies, when up/downshifting, or
when fully depressing accelerator pedal.
Normal
Cancel the VDC/TCS
function for the
inspection on a chas-
sis dynamometer.
For inspection of speedometer or other instruments, press
VDC OFF SW to turn VDC/TCS function off.
When accelerator pedal is depressed on a chassis dynamometer (fixed
front-wheel type), vehicle speed will not increase. This is not normal. It is
result of TCS being activated by stationary front wheels. Warning lamp
may also illuminate to indicate “sensor system error”. This is also nor-
mal, and is the result of the stationary front wheels being detected. To be
certain, restart engine, and drive vehicle at 30 km/h (19 MPH) or more.
Make sure warning lamp does not illuminate.
ABS operation (Longer stop-
ping distance) On roads with low friction coefficients, such as snowy roads or gravel
roads, vehicles with ABS may require a longer stopping distance. There-
fore, when driving on such roads, avoid overconfidence and keep speed
sufficiently low. Normal
Insufficient feeling of accel-
eration Depending on road conditions, driver may feel that feeling of accelera-
tion is insufficient. This is because traction control, which controls
engine and brakes to achieve optimal traction, has the highest priority
(for safety). As a result, there may be times when acceleration is slightly
less than usual for the same accelerator pedal operation. Normal