My ABS, VDC and Slip lights come on immediately upon starting my 2008 Nissan
Pathfinder and remain illuminated as soon as I drive it off the lot. Additionally, my
service engine light illuminates.
This error indicates that one or more ABS wheel speed sensors is malfunctioning and
sending false data to the vehicle’s computer, possibly as a result of:
Faulty ABS Sensors
When your ABS or traction control lights illuminate, they indicate that your vehicle’s
computer has detected a problem with an ABS sensor. This often happens when
road debris gets lodged inside it, stopping accurate signals from reaching your
computer. You can test this sensor using a multimeter in AC voltage mode with
probe attached – if its tip no longer detects voltage readings it must be replaced
immediately.
These sensors use a toothed metal ring and magnet to provide information about
wheel speed to an ABS module, sending data about how fast each wheel is rotating
to activate your brakes or any other modules that rely on ABS information. If just one
sensor fails, however, your brakes or any other modules that rely on its information
won’t function as intended.
Switching out an ABS sensor is generally straightforward, although you should refer
to your vehicle’s owner’s manual for specific instructions on its make and model.
Start by disconnecting your car’s positive cable before raising it on jack stands and
using a ratchet to detach its mounting bolt as well as remove any fasteners holding
the wiring harness together.
Faulty ABS Rings
The ABS system can respond rapidly to vehicle movements thanks to wheel speed
sensors that are attached to all four of your car’s wheels and monitor their speeds. If
one of these sensors malfunctions unexpectedly, PCM signals the traction
control/ABS light to illuminate.
The sensor itself consists of a tone ring with regularly spaced holes or teeth. Ferrous
metals such as cast iron and steel work best to transmit sensor signals to an
electronic control unit for use by programming software in activating brakes under
certain circumstances as determined by this electronic control unit.
If the tone ring on your car has broken, you should remove and inspect it closely for
corrosion damage. If this is present, a new tone ring may need to be purchased;
additionally, make sure that you use appropriate brake fluid in accordance with your
car model.
Faulty Wires
Your ABS and traction control systems rely on sensor data provided by wheel speed
sensors. These sensors track rate of speed change at each wheel, relaying that
information back to the ECU controlled ABS/traction control system. However, should
any of these sensors become defective they could send incorrect data that disables
these systems altogether.
When this occurs, it disables your system and prevents its use. This constitutes a
system failure and should be examined as quickly as possible by a certified
mechanic in order to identify and address its underlying issues – this may be either
mechanical or electronic in nature; if brake fluid levels drop significantly due to worn
pads reducing reservoir levels to their minimum or from overheated fluid being
introduced through worn tubes; switching out for one that is less prone to boiling
can help solve this problem.
Bad Camshaft Sensors
Camshaft sensors may sometimes malfunction and lead to these symptoms. When
their signal goes wrong, the onboard diagnostics system interprets it as mechanical
failure and shuts off Vehicle Dynamic Control system accordingly.
Over time, sensors may become contaminated with oil or debris and develop
corrosion on their electrical connectors and wires that connect them to the PCM,
leading to poor or no signals being sent back from them. This may result in
decreased signal strength or no signals at all being received back from them.
Replacing a camshaft sensor isn’t complicated or expensive; in fact, it’s usually one
of the simpler components on the car to replace. But before trying this DIY fix
yourself, always get professional help to evaluate and diagnose any potential
damage using an OBD 2 scan tool to read codes and get more accurate diagnosis of
damage; this can save money in the long run as they can also inspect for signs that
a bad camshaft sensor exists within your engine.