Replace the input speed sensor (turbine shaft speed sensor) on the 10R80 transmission, typically accessed from underneath the vehicle.

Warnings

Tools required

Parts

• Transmission Input/Turbine Speed Sensor × 1 — Ford BC3Z-7H103-B or equivalent
• Transmission fluid (for top-off) × 1 — Use OEM specification

Fluids

• Motorcraft MERCON LV ATF — 2 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Place wheel chocks behind rear wheels
3. If vehicle was recently driven, allow transmission to cool for at least 30 minutes
4. Raise front of vehicle using floor jack at designated lift points
5. Secure vehicle on jack stands at frame rails
6. Verify vehicle is stable before working underneath
7. Remove plastic engine undershield if equipped (multiple 8mm screws and push clips)

Procedure

1. 1

   Locate the input speed sensor
   From underneath the vehicle, locate the input speed sensor on the driver's side of the transmission bell housing area. The sensor is positioned near the front of the transmission case, typically identifiable by its electrical connector and single mounting bolt. On the 10R80 transmission, this is the turbine shaft speed sensor.
2. 2

   Position drain pan
   Place a drain pan directly beneath the input speed sensor location. Position it to catch approximately 1-2 quarts of transmission fluid that will drain when the sensor is removed. Ensure the pan has adequate capacity and is positioned to account for fluid flow.
3. 3

   Disconnect sensor electrical connector
   Press the locking tab on the electrical connector and carefully pull the connector away from the sensor. The connector may have a secondary lock or slide that must be released first. Inspect the connector pins for corrosion or damage. Move the harness aside to provide working clearance.
4. 4

   Remove sensor mounting bolt
   Using a 10mm socket, remove the single bolt securing the input speed sensor to the transmission case. Keep the bolt clean and inspect threads for damage. The bolt will be tight due to the sensor seal.
5. 5

   Extract the sensor
   Carefully pull the sensor straight out from the transmission case. You may need to gently wiggle and rotate the sensor to break the seal. Transmission fluid will begin draining immediately once the sensor is removed. Allow fluid to drain completely into the pan. Inspect the old sensor for metal shavings or debris on the magnetic tip, which could indicate internal transmission wear.
   ⚠Excessive metal debris on sensor tip may indicate transmission damage requiring further diagnosis.
6. 6

   Clean sensor bore
   Using a clean shop towel, carefully wipe the sensor mounting bore in the transmission case to remove any old seal material or debris. Do not insert anything into the bore that could fall into the transmission. Inspect the bore for damage to the sealing surface.
7. 7

   Prepare new sensor
   Remove the new sensor from packaging and verify it matches the old sensor design. Check that the O-ring seal is properly seated in the sensor groove. Lightly lubricate the O-ring with clean MERCON LV ATF to ease installation and prevent seal damage. Do not use petroleum-based lubricants.
8. 8

   Install new sensor
   Insert the new sensor straight into the transmission case bore, ensuring proper alignment. Push the sensor fully into position until it seats against the transmission case. The sensor should slide in smoothly without excessive force. Misalignment will prevent proper seating.
9. 9

   Install and torque mounting bolt
   Start the sensor mounting bolt by hand to ensure proper threading. Using a torque wrench, tighten the bolt to specification. Do not overtighten as this can damage the sensor housing or crack the transmission case.
   Torque spec

   Sensor Bolts12 Nm (9 lb-ft)
10. 10

    Reconnect electrical connector
    Align the electrical connector with the sensor terminals and push firmly until you hear or feel a click indicating the locking tab has engaged. Verify the connection is secure by gently pulling on the connector. If equipped with a secondary lock, ensure it is fully engaged.
11. 11

    Refill transmission fluid
    Locate the transmission dipstick tube (driver's side of engine bay on 3.5L EcoBoost). Remove the dipstick and insert a funnel. Add approximately 1.5-2.0 quarts of Motorcraft MERCON LV ATF to compensate for fluid lost during sensor replacement. Do not overfill at this stage.
12. 12

    Reinstall undershield and lower vehicle
    Reinstall the plastic engine undershield if it was removed, securing all fasteners and clips. Carefully raise the vehicle slightly to remove jack stands, then lower the vehicle completely to the ground.

Reassembly

1. Ensure all tools and drain pan are removed from underneath vehicle before lowering
2. Verify sensor electrical connector is fully seated and locked
3. Double-check torque on sensor mounting bolt
4. Properly dispose of old transmission fluid according to local regulations

Verification

• Start the engine and allow it to idle for 1-2 minutes
• With engine running and transmission in Park, check for transmission fluid leaks around the sensor installation area
• With parking brake engaged and foot on brake, shift through all gear positions (P-R-N-D and back to P), pausing 2-3 seconds in each position
• Check transmission fluid level with engine running at operating temperature and transmission in Park on level ground. Add fluid as needed to bring level to the HOT range
• Clear any diagnostic trouble codes using a scan tool if check engine light is illuminated
• Test drive vehicle to verify proper transmission operation and confirm no speed sensor related codes return
• Recheck fluid level after test drive and top off if necessary
• Final inspection underneath vehicle for any fluid leaks after test drive

More procedures for this vehicle