Troubleshooting Ford Taurus Anti-Lock Brakes

The 1990 through 1995 Ford Taurus came equipped with the Teves Mark 4 four wheel anti-lock brake system. This system was replaced in 1996 with the more compact Bosch 5.0 four wheel ABS system. Both systems control the front wheels independently and the rear wheels in tandem, and troubleshooting them is identical.

Testing with Scan Tools

Testing these anti-lock brake systems begins with a scan tool. It tells you where to start troubleshooting. The codes stored in the ABS computer indicate which sensor or circuit in the system has a problem. Datastream mode will allow you to see if the sensors are working, or not supplying the signal needed by the computer to control the system.

ABS-capable scan tools are available at your local auto parts store, and these days, troubleshooting many systems requires one. Look for one capable of interfacing your Taurus' ABS system.

There are two tests available with the scan tool. First, read trouble codes. This test will tell you which code(s) are stored in the computer's memory, and a description of the circuit or component that has the failure.

The datastream allows you to monitor the sensor signals as you drive the car. Scroll down to see the wheel speed sensor readings and drive. All four sensors should read roughly the same, and rise and fall steadily with the vehicle's speed.

Wheel Speed Sensor Testing

The most common cause of wheel speed sensor failures in the Taurus are contamination by metal particles from the brake system. If a trouble code for a sensor comes up, make removing and cleaning the sensor of metal the first thing you do. This will eliminate most failures here. The next test is a resistance test. Check for resistance at the sensor itself by measuring with an ohm meter. The sensor should have some resistance but be low. If a sensor has zero resistance or infinite resistance, replace it.

Modulator Valve Assembly Testing

The modulator valve assembly contains the solenoid valves that the computer opens and closes to control brake pressure at the wheels. To test those valves , unplug the electrical connector, and do a resistance check at each solenoid valve. Again, as with the wheel speed sensor, there will be some resistance. If a solenoid is found to have no resistance or infinite resistance, replace it.