Ford F-350 Rear ABS Wheel Speed Sensor Guide (1987-1998)
Solve your ABS light and erratic speedometer issues by understanding the single most important sensor in your truck's rear anti-lock brake system.
- Your F-350 has a single Rear ABS (RABS) sensor located on the rear differential.
- A faulty sensor will cause the ABS light, disable cruise control, and create speedometer and shifting problems.
- Replacement is very easy, requiring only the removal of one bolt and an electrical connector.
- Often the sensor tip just needs to be cleaned of metal shavings, but replacement with a quality aftermarket part is a reliable, inexpensive fix.
Understanding the F-350's RABS System
Your 1987-1998 Ford F-350 doesn't have a complex, four-sensor ABS system like modern trucks. It uses a simpler, more robust system called RABS (Rear Anti-lock Brake System). This system relies on a single magnetic sensor located on the top of your rear differential housing. Its job is to measure the speed of the rear wheels and prevent them from skidding. Because it also provides the vehicle speed signal for other components, a failure can cause more than just an ABS light.
Symptoms of a Failing Rear ABS Sensor
When this sensor starts to fail, your truck will give you clear signs. The most common cause of failure is the magnetic tip of the sensor becoming covered in fine metal particles from normal differential wear. This buildup interrupts the signal. Other causes include internal sensor failure or damage to the wiring harness.
- ABS Warning Light: The most obvious symptom is the amber 'ABS' light illuminating on your dashboard.
- Erratic or Dead Speedometer: The speedometer may jump around, read incorrectly, or drop to zero while driving. The odometer may also go blank.
- Harsh Transmission Shifting: If you have an automatic transmission, it may shift hard or at the wrong times because it isn't receiving an accurate speed signal.
- Cruise Control Inoperative: The cruise control system relies on this sensor's reading and will not function if the signal is lost.
Is It Safe to Drive?
You can still drive the truck, but with caution. Your standard braking system will function normally, but the anti-lock feature for the rear wheels will be disabled. This increases the risk of the rear wheels locking up and skidding during a panic stop, especially in wet or slippery conditions. The inaccurate speedometer is also a safety concern.
Choosing the Right Aftermarket ABS Sensor
Since the original Motorcraft sensor can be difficult to find for these model years, the aftermarket is your most likely source. Quality varies, but even a standard replacement is often a reliable fix for this simple part. Here’s a breakdown of available brands.
Premium Aftermarket Brands ($50 - $87.09)
These brands are known for quality materials and engineering, often meeting or exceeding original equipment (OE) specifications. They are a top choice for reliability.
- Delphi: A well-respected OE supplier for many manufacturers, Delphi is a trusted name for electronic components.
- NGK/NTK: While famous for spark plugs (NGK), their sensor line (NTK) is also regarded as a high-quality, reliable option.
- Standard Ignition (SMP): A long-standing brand in the aftermarket, Standard Motor Products is known for producing dependable sensors and ignition components.
Standard & Value Brands ($22.18 - $49)
These brands offer a balance of affordability and function, making them a popular choice for budget-conscious repairs.
- Dorman: Dorman provides a vast catalog of replacement parts and is often a suitable alternative to OEM parts, sometimes with design improvements.
- Holstein: This brand focuses on providing a cost-effective solution for repairs.
OEM vs. Aftermarket Quality
For a part like the RABS sensor on this generation of F-350, a quality aftermarket brand like Delphi or Standard is widely considered to be just as effective as the original Motorcraft part. Given the age of the vehicle and the simple magnetic design of the sensor, there is little risk in choosing a reputable aftermarket replacement.
Estimated Replacement Costs
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket Sensor | $22.18 - $87.09 |
| Shop Labor | $50 - $100 |
| Total Estimated Cost | $72.18 - $187.09 |
Cost estimates are for the part and labor only and do not include taxes, shop fees, or diagnostic charges.
Frequently Asked Questions
Where is the ABS sensor located on my 1987-1998 F-350?
It is located directly on top of the rear differential housing, in the center. It is held in by a single bolt and has a two-wire electrical connector.
Can I just clean my old sensor?
Sometimes, yes. The sensor's tip is a magnet that attracts metallic paste from the gear oil. You can remove the sensor and wipe the tip clean. If this restores function, the sensor itself is likely still good. If the symptoms return quickly or don't go away, the sensor has failed internally and must be replaced.
Is the replacement difficult to do myself?
No, this is one of the easiest repairs you can do. It requires basic hand tools to remove one bolt and unplug a connector. The entire job can typically be done in under 30 minutes.
Why did my speedometer and ABS light fail at the same time?
Because on these trucks, the single rear ABS sensor provides the speed signal for both the Rear Anti-lock Brake System and the speedometer. When the sensor fails, both systems lose their data source and stop working correctly.
Are there any recalls for this sensor?
No, there are no specific recalls from Ford or NHTSA for the ABS wheel speed sensor on the 1987-1998 Ford F-350 model years.
Technical Specifications
OEM Part Numbers: F85Z-9E731-AB
Location: Rear Differential Housing System Type: Rear Anti-lock Brake System (RABS) Quantity Required: 1
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Ford F-350:
- 🛍️ Shop This Part
- Understanding the F-350's RABS System
- Symptoms of a Failing Rear ABS Sensor
- Is It Safe to Drive?
- Choosing the Right Aftermarket ABS Sensor
- Premium Aftermarket Brands ($50 - $87.09)
- Standard & Value Brands ($22.18 - $49)
- OEM vs. Aftermarket Quality
- Estimated Replacement Costs
- Frequently Asked Questions
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