How to Identify Which ABS Sensor Is Bad in a 2005 F-150

The anti-lock braking system on a 2005 Ford F-150 has three sensors that relay information to the ABS computer about the rotational speed of the wheels. The front wheels have an individual ABS sensor attached to each wheel hub. The rear wheels use a single ABS sensor that attaches to the top of the differential housing. Because these sensors are computer-controlled components, an automotive scan tool with ABS functionality must be used to determine which sensor is not properly communicating with the ABS computer.

Things You'll Need

• Automotive scan tool
• Pen
• Paper

Instructions

1. Drive the vehicle to an empty parking lot or vacant street for testing. You’ll need to briefly read the scan tool while operating the vehicle, so choose a safe location for this procedure.

2. Shift the transmission into park and connect the scan tool’s data cable to the truck’s diagnostic data port, mounted under the leading edge of the lower dashboard panel about two inches to the right of the steering column centerline.

3. Turn on the scan tool and navigate to the ABS menu. From the ABS menu, select the live data screen. The live data screen shows real-time information from all of the anti-lock braking system’s electronic components, including the individual wheel speed sensors. The exact menu structure of your scan tool may differ slightly depending upon its brand and specific functionality.

4. Make sure the road ahead is clear and then drive the truck forward 50 to 100 feet. Glance down at the scan tool while the truck is moving and look at the speed listed for each ABS sensor on the scan tool’s screen. All of the sensors should match the reading on the truck’s speedometer and also agree with each other. The faulty sensor will show a speed of zero while the other sensors show the truck’s current speed.

5. Stop the truck and shift the transmission back into park. Note which sensor is faulty on a piece of paper; this is the sensor that needs to be replaced. Power down the scan tool and disconnect its data cable.

Tips & Warnings

• Automotive scan tools can be rented or purchased at most auto parts stores. However, many scan tools do not have ABS capabilities. You’ll need a scan tool that can communicate with the anti-lock braking system to properly determine which sensor is malfunctioning. The scan tools with ABS capabilities generally cost more to purchase but offer a much wider range of diagnostic abilities.

• Do not perform this test on a public street near pedestrians or other vehicles. Because it requires you to take your eyes off the road ahead for a moment, be sure that you're in a controlled area such as a parking lot or vacant street.

References

• Haynes Repair Manual: Ford Full Size Pick-Ups: 2004 Thru 2009; John Haynes and Jay Storer
• AllData Repair Database: 2005 Ford F-150