Speedometer Cable

Replace the speedometer cable or speed sensor connector on a 2007-2013 Mercedes-Benz S65 AMG, restoring proper speedometer and odometer function.

Warnings

Tools required

Parts

• Speedometer cable or speed sensor connector assembly × 1 — A2215400417 or equivalent
• Cable grommet/seal × 1 — Use OEM specification
• Electrical connector seals (if applicable) × 1 — Use OEM specification

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect battery negative terminal using 10mm socket
3. Wait minimum 10 minutes for electrical system discharge
4. Raise vehicle on lift or support securely on jack stands if accessing from below
5. Allow transmission to cool if vehicle was recently driven

Procedure

1. 1

   Access transmission tunnel and center console
   Remove center console trim panels to access transmission tunnel area. Use trim removal tools to carefully pry up the rear console trim panel, working from back to front. Disconnect any electrical connectors for seat controls or climate vents. Remove cover screws securing the transmission tunnel cover.
2. 2

   Remove transmission tunnel insulation
   Peel back or remove the sound insulation material from the transmission tunnel to expose the top of the transmission bellhousing area. This material is typically secured with clips and adhesive. Take care not to tear the insulation for reinstallation.
3. 3

   Locate speed sensor connector at transmission
   From above or below the vehicle, locate the transmission output speed sensor on the rear section of the 7-speed automatic transmission (722.9 series). The sensor is typically mounted on the driver's side of the transmission tail housing. Identify the wiring harness routing from the sensor to the instrument cluster connector.
4. 4

   Disconnect speed sensor electrical connector
   Press the locking tab on the speed sensor electrical connector and carefully pull the connector away from the sensor. If corrosion is present, spray with electrical contact cleaner and allow to dry before disconnecting. Inspect connector pins for damage or corrosion.
5. 5

   Remove speed sensor mounting bolt
   Using a 10mm socket, remove the mounting bolt securing the speed sensor to the transmission housing. Note the position of any ground straps or brackets attached to this bolt for proper reinstallation.
6. 6

   Extract speed sensor from transmission
   Carefully pull the speed sensor straight out from the transmission housing. There may be resistance from the O-ring seal. Inspect the sensor drive gear for damage. Remove and discard the old O-ring seal from the sensor body.
   ⚠A small amount of transmission fluid may leak when sensor is removed. Have a drain pan ready and inspect fluid level after reassembly.
7. 7

   Inspect and route new wiring harness
   If replacing the wiring harness (speedometer cable equivalent), route the new harness along the same path as the original, securing it with existing clips and ties. Ensure the harness does not contact hot exhaust components or sharp edges. Install new grommets where the harness passes through the transmission tunnel or firewall.
8. 8

   Install new or cleaned speed sensor
   Install a new O-ring seal on the speed sensor, lightly lubricating it with clean transmission fluid. Insert the sensor into the transmission housing, ensuring proper alignment of the drive gear. Push firmly until the sensor seats flush against the transmission case.
9. 9

   Secure sensor mounting bolt
   Install the mounting bolt and any ground straps in their original positions. If a ground strap is present, torque the bolt to the ground bolt specification. Otherwise, use the standard mounting bolt torque. Ensure the sensor is properly seated before final tightening.
10. 10

    Connect electrical connector
    Align and push the electrical connector onto the speed sensor until it clicks into place. Verify the locking tab engages fully. Gently tug on the connector to confirm it is secured.
11. 11

    Reinstall transmission tunnel components
    Replace the sound insulation material, ensuring it is properly positioned and secured with all original clips. Install the transmission tunnel cover and secure with cover screws. Reconnect any electrical connectors that were disconnected during disassembly.
12. 12

    Reconnect battery and clear fault codes
    Reconnect the battery negative terminal using a 10mm socket. Use a Mercedes-Benz Star Diagnostic tool or compatible scanner to clear any speed sensor or transmission fault codes that may have been stored. Initialize the transmission control module if required by the diagnostic tool.

Reassembly

1. Reinstall all center console trim panels in reverse order of removal
2. Verify all electrical connectors in console area are properly seated
3. Check transmission fluid level using dipstick (engine running, transmission at operating temperature, in Park position)
4. Top off transmission fluid with Mercedes-Benz ATF 134 if needed, typically only 0.1-0.2 quarts maximum

Verification

• Start the engine and verify no warning lights appear on the instrument cluster
• With engine running and brake applied, shift through all transmission gear positions to verify proper operation
• Perform a test drive and confirm speedometer displays correct vehicle speed at various speeds (use GPS for verification)
• Verify odometer is accumulating mileage correctly during test drive
• Check for transmission fault codes using diagnostic scanner after test drive
• Inspect speed sensor area for any transmission fluid leaks after test drive

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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