ABS Wheel Speed Sensor - Rear

This procedure covers the removal and replacement of a rear ABS wheel speed sensor on a 2007 Ram 3500 with the 5.9L Cummins diesel engine and 4WD.

Warnings

Tools required

Parts

• Rear ABS wheel speed sensor × 1 — Use OEM specification
• Sensor mounting bolt (if corroded) × 1 — Use OEM specification

Preparation

1. Park vehicle on level surface and apply parking brake
2. Place wheel chocks in front of front tires
3. If desired, connect scan tool to note which wheel is showing the fault code before beginning work
4. Loosen rear wheel lug nuts while vehicle is still on ground (do not remove)
5. Raise rear of vehicle and support securely on jack stands rated for vehicle weight
6. Remove rear wheel completely

Procedure

1. 1

   Locate the ABS wheel speed sensor
   On the 2007 Ram 3500, the rear ABS speed sensor is a single sensor mounted at the rear differential housing (near the pinion/center section of the AAM 11.5 axle), reading a tone ring inside the differential rather than at each wheel. Trace the sensor wire from the harness connector back to the sensor body at the differential.
2. 2

   Disconnect the sensor electrical connector
   Follow the sensor wire harness to locate the electrical connector, which is typically mounted to a bracket on the axle housing or frame rail. Press the connector release tab and pull the connector halves apart. Inspect the connector terminals for corrosion or damage.
3. 3

   Remove sensor wire harness clips
   Carefully release any wire harness clips or retaining brackets that secure the sensor wire to the axle housing, brake line, or frame. Note the routing of the wire for reinstallation. Use a flathead screwdriver to gently pry clips if necessary.
4. 4

   Remove sensor mounting bolt
   Remove the single retaining bolt that secures the ABS sensor to the differential/axle housing (verify bolt head size, commonly 8mm or 10mm, against the vehicle). If the bolt is corroded or difficult to turn, apply penetrating oil and allow it to soak. The bolt threads into the housing and may be seized.
5. 5

   Extract the ABS sensor
   Carefully pull the sensor straight out of the axle housing bore. If the sensor is seized, apply penetrating oil around the sensor body and allow it to penetrate for several minutes. Gently rock the sensor side-to-side while pulling outward. Do not use excessive force or pry against the sensor as this can damage the tone ring inside the axle.
6. 6

   Clean the sensor mounting bore
   Use a wire brush and brake cleaner to thoroughly clean the sensor mounting bore in the axle housing. Remove all rust, dirt, and debris. Ensure the bore is clean and smooth to allow proper seating of the new sensor and to prevent future seizing.
7. 7

   Prepare the new sensor
   Inspect the new ABS sensor to ensure it matches the old unit. Apply a thin coat of anti-seize compound to the sensor body (not the tip) to prevent future corrosion and ease future removal. Apply dielectric grease to the electrical connector terminals to protect against moisture.
8. 8

   Install the new sensor
   Carefully insert the new sensor straight into the axle housing bore, ensuring it seats fully. The sensor should slide in smoothly without force. If resistance is felt, remove and check for obstructions in the bore. The sensor tip must be positioned close to the tone ring but not touching it.
9. 9

   Install and tighten the mounting bolt
   Thread the mounting bolt by hand to prevent cross-threading, then tighten with the appropriate socket. If a torque specification is not available, tighten the bolt firmly (approximately 7-9 ft-lbs) but do not overtighten as this can crack the sensor body or strip the threads in the housing.
10. 10

    Route and secure the sensor harness
    Route the sensor wire harness along the original path, ensuring it does not contact any moving parts, sharp edges, or heat sources. Secure all wire harness clips and brackets. Ensure there is adequate slack for axle movement but not so much that the wire can hang down.
11. 11

    Reconnect the electrical connector
    Connect the sensor electrical connector to the vehicle harness, ensuring it clicks firmly into place. Gently tug on the connection to verify it is secure. Ensure the connector is properly sealed to prevent moisture intrusion.
12. 12

    Reinstall the wheel
    Reinstall the rear wheel and thread the lug nuts by hand. Tighten the lug nuts in a star pattern while the vehicle is still on jack stands, then lower the vehicle to the ground. Torque the lug nuts to the OEM specification (approximately 145 ft-lbs for single-rear-wheel; follow the dual-rear-wheel two-stage procedure if equipped) in a star pattern. Lug nut socket sized to the vehicle (verify — commonly 22mm on single-rear-wheel or 33mm on dual-rear-wheel Ram 3500).

Reassembly

1. Ensure all wire harness clips are properly secured and the sensor wire is not pinched or rubbing
2. Verify the electrical connector is fully seated and locked
3. Check that the sensor mounting bolt is tight and the sensor is not loose in the bore

Verification

• Start the engine and verify the ABS warning light on the instrument cluster goes off after a few seconds (indicating successful initialization)
• If equipped with a scan tool, clear any stored ABS codes and verify no new codes are present
• Test drive the vehicle at low speed (15-25 mph) to allow the ABS system to perform a self-check and verify proper sensor operation
• After test drive, use scan tool to verify the rear wheel speed sensor is reading correctly and matches the opposite side sensor reading
• Perform a controlled ABS activation test in a safe area if necessary to confirm full system function

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

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