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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, 10mm socket, T30 Torx, floor jack, jack stands, wheel chocks, safety glasses, torque wrench, lug wrench

Applicable Models:

Volvo V70 (1998-01)
Volvo V70 2.4T (2001)
Volvo V70 AWD (1998-99)
Volvo V70 GLT (1998-00)
Volvo V70 GLT SE (2000)
Volvo V70 R (1998)
Volvo V70 R AWD (1999-00)
Volvo V70 T5 (1998-01)
Volvo V70 X/C (2001)
Volvo V70 X/C AWD (1998-00)
Volvo V70 X/C AWD SE (2000)

Parts Required:

ABS wheel speed sensor, Molykote Longterm 2 grease

Hot Tip:

Check for fault codes before replacing

Performance Gain:

Repair faulty ABS sensor

Complementary Modification:

Properly route wiring, use new clips if needed

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. Sensors are bolted to each wheel hub and are therefore susceptible to damage from impacts, road grime and brake dust.

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, other problems can illuminate the ABS/DSC warning light. Be sure to scan and read fault codes before replacing parts.

You can use a scan tool while monitoring wheel speed signals to check for a slower or faster wheel. This can help to pinpoint a faulty sensor. Compare all four-wheel speed signals together. Look for one that doesn't match the others. Another way to test the sensor is with a digital oscilloscope and monitor the waveform (the voltage output over time that the sensor creates).

In this tech article, I will go over how to replace the front and rear wheel speed sensors. The rear sensors are combined into one wiring harness and have to be replaced in pairs.

Remember that your car may have been serviced before and had 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 you're 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. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

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

Front sensor: Working between the front strut and brake rotor, remove the 10mm sensor mounting fastener (red arrow).
Figure 1

Front sensor: Working between the front strut and brake rotor, remove the 10mm sensor mounting fastener (red arrow).

Front sensor: Then remove the sensor wiring harness from the mounts (red arrows) on the strut by pulling them straight out.
Figure 2

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

Front sensor: Using a flathead screwdriver (red arrow), lever the sensor flange (green arrow) side to side to free the sensor from the wheel bearing carrier.
Figure 3

Front sensor: Using a flathead screwdriver (red arrow), lever the sensor flange (green arrow) side to side to free the sensor from the wheel bearing carrier.

Front sensor: Pull the ABS sensor out of the steering knuckle.
Figure 4

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

Front sensor: Working in the engine compartment, disconnect the electrical connector by pressing the release tab (green arrow) and sliding the sensor side connector out of the housing (inset).
Figure 5

Front sensor: Working in the engine compartment, disconnect the electrical connector by pressing the release tab (green arrow) and sliding the sensor side connector out of the housing (inset). The left side connector (red arrow) is located below the electrical box, just in front of the brake master cylinder. Install a new sensor with a thin coating of Molykote Longterm 2 or similar grease to the ABS sensor and housing. Install the fastener and tighten. Then route the wiring harness as it was before and reconnect it at the housing.

Front sensor: The right side electrical connector is located at the firewall, near the right side strut tower (red arrow).
Figure 6

Front sensor: The right side electrical connector is located at the firewall, near the right side strut tower (red arrow).

Rear sensor: Working behind the rear brake rotor, clean out the Torx fastener using a small pick.
Figure 7

Rear sensor: Working behind the rear brake rotor, clean out the Torx fastener using a small pick. I find they get quite dirty in my area and not clearing the dirt can lead to stripped fasteners. Use a T30 Torx bit and remove the sensor fastener (red arrow). Repeat these steps for the right side sensor.

Rear sensor: Pull the ABS sensor out of the wheel bearing carrier (red arrow).
Figure 8

Rear sensor: Pull the ABS sensor out of the wheel bearing carrier (red arrow). If the sensor does not slide out easily, lever it out using a flathead screwdriver. Lever close to the sensor (yellow arrow) and wiggle it out slowly. Repeat these steps for the right side sensor.

Rear sensor: Then remove the sensor wiring harness from the mounts (red arrows) on the trailing arm by pulling them straight out.
Figure 9

Rear sensor: Then remove the sensor wiring harness from the mounts (red arrows) on the trailing arm by pulling them straight out. Then unclip the wiring harness from the brake lines running along the trailing arm. Repeat these steps for the right side sensor.

Rear sensor: Working in the cargo compartment, remove the storage compartment lid by opening it and lifting it (green arrow) out of the mount (red arrow).
Figure 10

Rear sensor: Working in the cargo compartment, remove the storage compartment lid by opening it and lifting it (green arrow) out of the mount (red arrow).

Rear sensor: Slide the carpet panel out of the storage compartment (red arrow).
Figure 11

Rear sensor: Slide the carpet panel out of the storage compartment (red arrow).

Rear sensor: Pull the side trim panel (red arrow) up to remove it.
Figure 12

Rear sensor: Pull the side trim panel (red arrow) up to remove it. The right side is shown. Repeat this step for the left side.

Rear sensor: Remove the two 10mm storage lid fasteners (red arrows).
Figure 13

Rear sensor: Remove the two 10mm storage lid fasteners (red arrows). The right side is shown. Repeat this step for the left side.

Rear sensor: Remove the storage lid from the vehicle (red arrow) to expose the wiring harness junction (green arrow).
Figure 14

Rear sensor: Remove the storage lid from the vehicle (red arrow) to expose the wiring harness junction (green arrow).

Rear sensor: Working at the fuel pump access panel, remove the five 10mm fasteners (red arrows).
Figure 15

Rear sensor: Working at the fuel pump access panel, remove the five 10mm fasteners (red arrows). Then remove the access panel from the vehicle (inset).

Rear sensor: Unplug the wheel speed sensor connector (red arrow) by opening the clips (green arrows) and pulling it apart.
Figure 16

Rear sensor: Unplug the wheel speed sensor connector (red arrow) by opening the clips (green arrows) and pulling it apart. Then remove the wiring harness from the insulation (green arrow).

Rear sensor: Attach mechanic's wire to the electrical connector (green arrow).
Figure 17

Rear sensor: Attach mechanic's wire to the electrical connector (green arrow). This will help with reinstalling the new sensors.

Rear sensor: Working at the right corner of the fuel tank (green arrow), pull the wiring harness down and out of the mount (red arrow).
Figure 18

Rear sensor: Working at the right corner of the fuel tank (green arrow), pull the wiring harness down and out of the mount (red arrow). Then feed the sensor harness out of the vehicle. Be careful not to pull it too far. You don't want the mechanic's wire to fall through the fuel pump hole.

Rear sensor: Install the new sensors with a thin coating of Molykote Longterm 2 or similar grease to the ABS sensor and housing.
Figure 19

Rear sensor: Install the new sensors with a thin coating of Molykote Longterm 2 or similar grease to the ABS sensor and housing. Route the wiring harness near all he mounts; do not attach it yet. Note the yellow stripes on the harness. This indicates the areas it attaches to the mounts on the trailing arm. Attach the mechanic's wire to the new sensor electrical connector. Pull the new harness up through the access hole (red arrow). I like to feed it up the right side of the tank, as there is more room there. Connect the connector. Then attach the wiring harness to the mounts under the vehicle. Reassemble the interior and clear any fault codes.

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Page last updated: Wed 12/7/2016 02:49:11 AM