This procedure covers the removal and replacement of the output shaft speed sensor on the 10R80 automatic transmission, accessed from underneath the vehicle.

Warnings

Tools required

Parts

• Output shaft speed sensor (OSS) × 1 — Motorcraft DY-1282 or equivalent
• Transmission fluid (top-off) × 1 — Motorcraft MERCON LV ATF

Fluids

• Motorcraft MERCON LV ATF — 0.5 qt

Preparation

1. Park vehicle on level ground, engage parking brake, and place wheel chocks behind rear wheels
2. Allow transmission and exhaust system to cool completely (minimum 30 minutes after engine shutdown)
3. Raise front of vehicle with floor jack and support securely on jack stands rated for vehicle weight
4. Verify vehicle is stable before working underneath
5. Locate the output shaft speed sensor on the driver's side rear of the transmission case, near the tailshaft housing

Procedure

1. 1

   Access the output shaft speed sensor
   Position yourself under the vehicle with adequate lighting. Locate the output shaft speed sensor on the driver's side of the transmission, near the rear tailshaft housing. It will have a single electrical connector and is secured by one 10mm bolt. Clean any dirt or debris from around the sensor area with a wire brush or shop towel to prevent contamination.
2. 2

   Disconnect electrical connector
   Press the locking tab on the electrical connector and carefully pull the connector away from the sensor. If the connector is stuck due to corrosion or debris, gently wiggle it while pulling. Do not force or pull on the wiring harness itself. Inspect the connector terminals for corrosion or damage.
3. 3

   Position drain pan
   Place a small drain pan or shop towels directly beneath the sensor location. When the sensor is removed, transmission fluid will drain from the sensor bore. Expect approximately 0.25 to 0.5 quarts of fluid loss depending on fluid level and vehicle orientation.
4. 4

   Remove sensor retaining bolt
   Using a 10mm socket and ratchet, remove the single bolt securing the output shaft speed sensor to the transmission case. Keep the bolt in a safe location for reinstallation or replacement with the new sensor if a bolt is included.
5. 5

   Extract the sensor
   Carefully pull the sensor straight out from the transmission case. If the sensor is stuck, gently twist it while pulling outward. Do not pry against the transmission case as this may cause damage. Fluid will begin to drain once the sensor is removed. Allow fluid to drain into the pan for 1-2 minutes.
6. 6

   Inspect sensor bore and O-ring
   Examine the sensor bore in the transmission case for debris, metal shavings, or damage. If present, carefully clean with a lint-free shop towel. Do not insert anything deep into the bore. Inspect the old sensor O-ring (located on the sensor body) for damage, cuts, or deterioration. The new sensor should come with a new O-ring pre-installed.
7. 7

   Prepare new sensor
   Remove the new output shaft speed sensor from packaging. Verify the new O-ring is properly seated in the groove on the sensor body. Lightly coat the O-ring with clean MERCON LV transmission fluid to aid installation and prevent O-ring damage. Do not use petroleum-based lubricants.
8. 8

   Install new sensor
   Carefully insert the new sensor straight into the transmission case bore, ensuring proper alignment. Push the sensor in until it seats fully against the transmission case. The sensor should slide in smoothly without excessive force. Do not twist or force the sensor as this may damage the O-ring or sensor tip.
   Torque spec

   Sensor Bolts14 Nm (10 lb-ft)
9. 9

   Secure sensor with retaining bolt
   Install the sensor retaining bolt and hand-tighten. Using a torque wrench, tighten the bolt to 14.0 Nm (10.0 lb-ft) per specification. Do not overtighten as this may crack the sensor body or strip the threads in the aluminum transmission case.
   Torque spec

   Sensor Bolts14 Nm (10 lb-ft)
10. 10

    Reconnect electrical connector
    Push the electrical connector firmly onto the new sensor until you hear or feel a positive click, indicating the locking tab has engaged. Gently tug on the connector (not the wiring) to verify it is fully locked in place. Route any wiring away from hot exhaust components and sharp edges.
11. 11

    Check and top off transmission fluid
    Lower the vehicle to the ground. Start the engine and allow it to reach normal operating temperature. With the engine running and transmission in Park on level ground, check the transmission fluid level using the dipstick or fill plug procedure per manufacturer specifications. Add MERCON LV fluid as needed to bring level to the proper range, typically 0.25-0.5 quarts to replace what was lost.

Reassembly

1. Ensure electrical connector is fully engaged with locking tab secured
2. Verify sensor mounting bolt is torqued to specification and sensor is seated flush
3. Clean up any spilled transmission fluid from undercarriage components
4. Remove jack stands and lower vehicle completely to ground

Verification

• Start the engine and verify no transmission fluid leaks are present around the sensor
• Use a scan tool to verify the transmission control module is receiving output shaft speed sensor signal (should read 0 RPM in Park with engine running, and display speed when driving)
• Clear any stored diagnostic trouble codes related to the output shaft speed sensor
• Test drive the vehicle at various speeds and verify transmission shifts normally without slipping or harsh engagement
• Verify no check engine light or transmission warning lights are illuminated after test drive
• Recheck transmission fluid level after test drive and top off if necessary

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