Transmission Speed Sensor - Input

This procedure covers the removal and replacement of the input speed sensor on the 48RE automatic transmission in a 2007 Ram 3500 with the 5.9L Cummins diesel engine.

Warnings

Tools required

Parts

• Input speed sensor × 1 — Use OEM Mopar specification or quality equivalent
• O-ring seal for sensor × 1 — Often included with sensor

Fluids

• ATF+4 — 1 qt

Preparation

1. Park vehicle on level ground and engage parking brake
2. Allow transmission to cool if recently driven
3. Raise and safely support the front of the vehicle on jack stands
4. Place wheel chocks behind rear wheels
5. Disconnect negative battery cable to prevent fault code issues during sensor replacement

Procedure

1. 1

   Locate the input speed sensor
   From under the vehicle, locate the input speed sensor on the driver's side of the 48RE transmission case. Refer to factory service documentation to confirm the exact sensor location and orientation before removal, as it differs from the output speed sensor.
2. 2

   Disconnect the electrical connector
   Press the locking tab on the electrical connector and pull it straight off the input speed sensor. If the connector is stuck due to corrosion, gently wiggle it while pulling. Do not use excessive force on the wiring harness.
3. 3

   Position drain pan
   Place a drain pan directly beneath the sensor location. Expect approximately 1-2 cups of ATF+4 fluid to drain when the sensor is removed.
4. 4

   Remove the sensor retaining bolt
   Using a metric socket, remove the single bolt that secures the input speed sensor to the transmission case. Verify the bolt size against factory documentation. Keep the bolt for reinstallation.
5. 5

   Extract the sensor
   Carefully pull the input speed sensor straight out of the transmission case. Do not twist or rock excessively. If stuck, use a slight twisting motion while pulling. Allow fluid to drain into the pan.
6. 6

   Clean the mounting bore
   Using a shop towel and wire brush if needed, clean the sensor mounting bore in the transmission case. Remove any old O-ring material, debris, or metal particles. Ensure the surface is clean and free of damage.
7. 7

   Inspect and prepare the new sensor
   Verify the new input speed sensor matches the old unit. Check that a new O-ring is installed on the sensor body. Lightly lubricate the O-ring with clean ATF+4 to ease installation and prevent damage.
8. 8

   Install the new sensor
   Carefully insert the new input speed sensor straight into the transmission case bore. Push firmly until the sensor seats fully and the mounting flange is flush against the transmission case. Do not force or cross-thread.
9. 9

   Secure the sensor
   Install the retaining bolt and tighten to the factory-specified torque (typically around 8-10 ft-lbs for this M6-class fastener; verify against factory documentation). Do not overtighten as this can crack the sensor body or damage the transmission case threads.
10. 10

    Reconnect the electrical connector
    Push the electrical connector onto the sensor until it clicks into place. Verify the locking tab is fully engaged. Gently tug on the connector to confirm it is secure.
11. 11

    Check and top off transmission fluid
    Lower the vehicle and check the transmission fluid level with the engine running and transmission at operating temperature. Add ATF+4 as needed to bring the level to the proper range on the dipstick. Typically 0.5-1 quart will replace what was lost.
12. 12

    Reconnect battery and clear codes
    Reconnect the negative battery cable. Start the engine and verify no transmission warning lights are illuminated. If a check engine light is present, use a scan tool to clear any speed sensor related fault codes that were set during the repair.

Reassembly

1. Ensure the sensor retaining bolt is tight and the electrical connector is fully seated
2. Confirm transmission fluid level is correct after test drive
3. Inspect for any fluid leaks around the sensor after running the vehicle

Verification

• Start the engine and shift through all gear ranges to verify normal operation
• Test drive the vehicle and confirm smooth shifting with no transmission faults
• Use a scan tool to verify the input speed sensor is reading properly and providing data to the PCM
• Check for any fluid leaks around the sensor after the test drive
• Verify no check engine light or transmission warning lights are present

Related trouble codes on this vehicle

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

Chasing one of these codes and not sure which part is guilty? Ask a master mechanic about YOUR car →

More procedures for this vehicle