A technician can now control and test all lighting, ABS and air brake circuits with the provided tablet while conducting a walk around PMI or DOT inspection.
The key to accurate diagnosis is having an enhanced scanner that will allow you to get into the system to retrieve fault codes and the appropriate data.
Indirect Tire Pressure Monitoring Systems (TPMS) are the systems that do not have air pressure sensors inside the tires. Rather, they detect a low tire by comparing relative wheel speeds via the Anti-lock Brake System (ABS) wheel speed sensors. New systems are taking advantage of better wheel speed sensors and modules to make indirect systems work. Indirect TPMS began making a comeback in 2011 on all Audi models. The highly popular Honda Accord switched to indirect TPMS for the 2013 model year.
Some customers may experience an ETC light illumination. Upon further investigation, the technician may find that DTCs P2122 – Accelerator Pedal Position Sensor 1 Circuit Low and/or P2127 – Accelerator Pedal Position Sensor 2 Circuit Low have been set.
Monday mornings are typically not very productive for me. I typically will hide in my office with the light off to avoid people asking about their latest weekend-induced car problems.
If you confirm that the ABS light is on with one or more of the following DTCs stored – C1105, C1110, C1124, C1126 – and/or the ABS system activates with normal braking, follow the Service Procedure.
The front wheel bearings listed in this Tech Tip all share a unique design feature. They are all double-row angular contact with a split inner ring. The distinctive feature on these bearings is that one of the two seals on the bearing has a built-in magnetic impulse wheel. Caution should be taken to make sure that the seal with the ABS impulse ring is installed in the correct direction.
The passive wheel speed sensor has been around a long time. It works quite differently than the active speed sensors that are found on most cars today. The passive speed sensor creates its own AC signal that changes frequency with wheel speed. This signal is only present while the wheel is turning at a rate fast enough to create the AC signal.
Some drivers may notice a howl or groan sound while driving straight after a low speed spirited turning event. On SRT vehicles only, when the vehicle has been switched to the “Full On” ESP mode, the ESP event lamp continues to flash. This does not affect the functionality of the ESP system in any way. The system can be returned to “normal Full-On” mode by briefly pressing and releasing the ESP Off switch. The system will reset itself each time the ignition is cycled.
There are two “types” of sensors generally found on the modern car – the passive speed sensor and the active speed sensor. They both perform the same function, but work entirely different. The passive speed sensor uses a magnet with fine copper wire wrapped around it to create its own alternating magnetic field. The polarity changes from positive to negative as the tone ring passes by the magnetic field. This frequency changes with wheel speed.
If you are replacing a wheel bearing on a late-model vehicle, you will be dealing with a wheel speed sensor. In the past decade, wheel speed sensors have been moving from differentials, axles and knuckles to inside or on the wheel bearing or hub unit. At this location, the sensors are more accurate and often more protected from the elements.
There was a time when advancements in brake technology were entirely hardware based. The change from drum brakes to disc brakes, the introduction of semi-metallic and ceramic brake pads, and the addition of power brakes as standard equipment were all changes that were all achieved by redesigned and improved brake system components. Today, electronics is driving most of the advancements in braking technology.