2011 Volvo XC90 R-Design, FWDFACTORY OEM SERVICE PROCEDURE

Electrical Components - Design And Function: Transmission: Overview

Fig 1: Identifying Transmission
GLL157500Courtesy of VOLVO CARS CORPORATION

AW55-51 is a 5 speed electronically controlled automatic transmission with a lock-up function for the three highest gears. The transmission control module (TCM) adapts the gear changes to ensure that the correct gear is selected for the driving mode, engine load, driver requirements, speed etc. This gives good fuel economy combined with increased comfort by ensuring smoother gear changes and lower noise levels.

In a vehicle with an automatic transmission, the driver neither needs to decide which gear should be used nor shift gear. There is a operating system in the AW55-51 which uses a torque converter and gear shift system to do this.

Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.

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