Saturn Repair Questions? Ask a Mechanic for Answers ASAP
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First thing to do is to check all the fuses.
Since Saturn is/was made by GM, the ABS/TRAC systems are basically the same. GM system.
The Traction Control and Anti lock brake systems are linked together on this vehicle. The system is complex, quite advanced, and very precise. But, since it is so precise, this problem is rather common on this vehicle and the diagnostic process is not all that simple if no code is stored.
The Anti lock Brake and Traction Control computer (ABS/TRAC Module) reads all 4 wheel speed sensor readings. If the module notices that one wheel is spinning faster than the rest, it will apply brake pressure to that wheel to slow it down and a message will appear on the driver information center. If the Module notices that a wheel is spinning slower than the rest, it will release brake pressure to that wheel to keep it from skidding.
The WHEEL SPEED sensors are quite simple. They consist of a magnet and 2 wires. A tone ring is used as a rotating device attached to each wheel hub. As the tone ring rotates next to the magnet, an A/C voltage is induced. The faster the wheel rotates, the faster the tone ring rotates past the magnetic sensor, the higher the A/C voltage.
These sensors are common to fail intermittently sending a higher or lower voltage to the module. The module then believes that a wheel is spinning faster or slower than it actually is. As a result, the ABS/TRAC Module performs its duties and releases or applies brake pressure to the corresponding wheel. In some cases it is common for the vehicle to lose power and even stall due to the brake pressure applied to the wheels, especially the front drive wheels.
Since the Module simply sees a higher voltage or lower voltage, it assumes that the wheel(s) have spun or locked up as normal driving characteristics. Therefore, a diagnostic trouble code is often not set by the Module since the condition is assumed to be not a failure but a normal operational characteristic. In my opinion, the system could have been better designed with better software in the Module. But, that's GM for you...
Now, for diagnosing the problem...
The easiest was is with a scan tool which has the capabilities to access the live data from the ABS/TRAC Module. You set up the 4 wheel speed sensors on the scan tool screen in graph form. When the problem occurs, a speed sensor reading will spike up or down depending on the failure type. You have now found the affected wheel.
The other way is to use an oscilloscope with 2 or (better) 4 channels. By hooking up the scope to the sensors, you can see the A/C voltage pattern on the screen. When the sensor acts up, it will be clear as the clean waveform of an A/C voltage pattern will turn spiky or drop out.
The third way will be trickier and will require at least one volt meter and an assistant. You hook up the volt meter or volt meters to the sensor(s) and set the voltage reading to A/C voltage. While driving the vehicle, when the problem occurs you will notice that the voltage will spike or drop out for the faulty sensor. But, if you only have one volt meter, you will repeat and duplicate the process up to 4 times to pinpoint the faulty sensor.
Once you find which wheel is affected, CLOSELY inspect the connections and the wiring from the sensor to the Module. If the wiring looks good, replace the sensor.