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ABS Wheel Speed Sensor Replacement
 
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Pelican Technical Article:

ABS Wheel Speed Sensor Replacement

Nick Czerula

Time:

2 hours2 hrs

Tab:

$150

Talent:

****

Tools:

Flathead screwdriver, 5mm Allen bit, '-inch drive ratchet with 4-inch extension, floor jack, two jack stands, two wheel chocks, safety glasses

Applicable Models:

BMW X5 (2000-06)

Parts Required:

ABS wheel speed sensor (front or rear), Molykote Long Term 2 grease

Hot Tip:

Check for fault codes before replacing

Performance Gain:

Repair faulty ABS sensor

Complementary Modification:

Properly route wiring and use new clips if needed

One of the most important safety developments for automobiles are anti-lock brake systems. In an ABS system there is a sensor mounted in the hub that measures the individual wheel speeds of all four wheels. Under braking, if one wheel is traveling slower than the others the ABS computer realizes the wheel is locking up. A locked up wheel no longer reacts to steering inputs and the car will slide until it stops. This reduces the ability of the driver to control the car. Here the ABS computer can control the brake pressure to the locked up wheel. If the wheel is locked up the ABS computer can reduce brake pressure to that wheel. As the wheel speed sensor indicates the wheel is traveling at the same speed as the others, the ABS computer allows pressurized brake fluid to the caliper to continue to slow down the wheels. This process alternates back and forth until the wheel speeds are under control. This allows the driver to come to a safe and controlled stop.

The ABS wheel speed sensor monitors road wheel movement and sends an electronic signal to the ABS / DSC module. This signal is used to calculate road wheel speed to help with ABS braking and stability control features. BMW E53 models utilize a magneto resistive style sensor. When an ABS wheel speed sensor fails, the ABS/DSC module loses road wheel speed for the corresponding wheel and sets a fault code for the ABS wheel speed signal. When a fault code is set, the ABS/DSC warning light will illuminate. You will have to scan the module and read the fault codes to determine which speed sensor is the problem. Keep in mind that other problems can illuminate the ABS/DSC warning light. Be sure to scan and read fault codes before replacing parts.

Remember your car may have been serviced before and parts replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

Our vehicle may vary slightly from yours as models do change and evolve as they grow older. If something seems different, let us know and share your info to help other users. Questions or want to add to the article? Leave a comment below.

In this tech article, I will go over how to replace the front and rear ABS wheel speed sensors on BMW E53 vehicles.

Lift the axle of the vehicle you are replacing the ABS sensor on. See our tech article on jacking up your vehicle.

Front sensor: 
Front sensor: The front ABS wheel speed sensor is mounted to the front of the wheel bearing carrier (red arrow).
Figure 1

Front sensor: The front ABS wheel speed sensor is mounted to the front of the wheel bearing carrier (red arrow).

Front sensor: Working behind the front strut (red arrow), open the plastic door (green arrow) for the ABS sensor electrical connector.
Figure 2

Front sensor: Working behind the front strut (red arrow), open the plastic door (green arrow) for the ABS sensor electrical connector.

Front sensor: Pull the ABS sensor electrical connector (red arrow) out of its holder.
Figure 3

Front sensor: Pull the ABS sensor electrical connector (red arrow) out of its holder. Disconnect it by pressing the release tab and pulling it apart. Be careful, these connectors become brittle over time and can crack if squeezed too hard. 

Front sensor: Then remove the sensor wiring harness from its mounts (red arrows) on the strut by pulling it straight out.
Figure 4

Front sensor: Then remove the sensor wiring harness from its mounts (red arrows) on the strut by pulling it straight out.

Front sensor: Working at the steering knuckle, remove the ABS sensor 5mm Allen fastener (red arrow).
Figure 5

Front sensor: Working at the steering knuckle, remove the ABS sensor 5mm Allen fastener (red arrow).

Front sensor: Pull the ABS sensor out of the steering knuckle.
Figure 6

Front sensor: Pull the ABS sensor out of the steering knuckle. Then remove it from the vehicle. If the sensor does not slide out easily, pull it out using a pair of pliers. Grab the sensor and twist it to break it free. Install the new sensor with a thin coating of Molykote Long Term 2 or similar grease to the ABS sensor and housing. Install the fastener and tighten it. Then route the wiring harness as it was before and reconnect it at the housing.

Rear sensor:
Rear sensor: The rear ABS sensor is mounted in the top of the rear wheel bearing carrier.
Figure 7

Rear sensor: The rear ABS sensor is mounted in the top of the rear wheel bearing carrier. This photo shows the sensor (red arrow) viewed from above.

Rear sensor: Working in front of the rear strut (yellow arrow), open the plastic door (red arrow) for the ABS sensor electrical connector.
Figure 8

Rear sensor: Working in front of the rear strut (yellow arrow), open the plastic door (red arrow) for the ABS sensor electrical connector.

Rear sensor: Pull the ABS sensor electrical connector out of the holder.
Figure 9

Rear sensor: Pull the ABS sensor electrical connector out of the holder. Disconnect it by pressing the release tab and pulling it apart. Be careful as these connectors become brittle over time and can crack if squeezed too hard. 

Rear sensor: Then remove the sensor wiring harness from the mounts (red arrows) and feed it out from behind the strut.
Figure 10

Rear sensor: Then remove the sensor wiring harness from the mounts (red arrows) and feed it out from behind the strut.

Rear sensor: Then open the wiring harness mounts (red arrows) using a flathead screwdriver.
Figure 11

Rear sensor: Then open the wiring harness mounts (red arrows) using a flathead screwdriver. Unclip and remove the ABS wheel speed sensor from its mounts.

Rear sensor: Working at the rear wheel bearing carrier, remove the ABS sensor 5mm Allen fastener (red arrow).
Figure 12

Rear sensor: Working at the rear wheel bearing carrier, remove the ABS sensor 5mm Allen fastener (red arrow). Using a 1/4-inch drive ratchet with a 4-inch extension makes it easier to get to the fastener.

Rear sensor: Pull the ABS sensor out of the wheel bearing carrier.
Figure 13

Rear sensor: Pull the ABS sensor out of the wheel bearing carrier. If the sensor does not slide out easily, pull it out using a pair of pliers. Grab the sensor and twist it to break it free. Install the new sensor with a thin coating of Molykote Long Term 2 or similar grease to ABS sensor and housing. Install the fastener and tighten it. Then route the wiring harness as it was before.

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Comments and Suggestions:
Hai Comments: If I'm correct a BMW e53 uses the following sensors:
- 2x speed sensors
- 2x brake sensors

Please confirm if this is correct
September 26, 2016
  Followup from the Pelican Staff: four wheel speed sensors. Two brake pad wear sensors. - Nick at Pelican Parts  
Lx2 Comments: I have a 2005 X5 and the front speed sensors are reading half the speed from the back and the actual MPH. These are new sensors that I have just installed. On my SnapOn Solus it is giving me a fault code of 5E24, 5E4E, and 5E5C Wheel speed sensor front left supply, Wheel Speed sensor front right supply and Wheel speed sensor generic. Any ideas on what type problem I am having and a solution to the problem. Thanks
December 15, 2014
  Followup from the Pelican Staff: Could be a faulty grounds to the sensors. I would check the signals of the good sensors using a lab scope, then compare them to the bad ones. - Nick at Pelican Parts  

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Page last updated: Sat 12/3/2016 02:44:24 AM