The steering wheel module is at the top of the steering column and controls signals for many things such as steering wheel angle information, audio system volume control, phone module menu selection, traffic information, wipers, cruise control, and lighting indicators. It is in constant communication with other control modules in the vehicle via a Databus and has a self-diagnosis facility that can be accessed via the diagnostic connector in the vehicle. To remove the module requires removing the steering wheel, then unscrewing the Torx screws from the steering column lower shroud, unclipping the gaiter and disconnecting the upper and lower shrouds. The wiper/washer and turn indicator switches are thereafter removed and access is gained to the module, which is undone by undoing screws and disconnecting wiring plugs. Refitting means reversing the steps of removing the modules, and if a new module is installed, new software will have to be downloaded from Volvo. For the keyless vehicle module the front left-hand seat is removed and wiring plugs removed and screws undone for removal of the module with the reverse being the process for refitting. The rain sensor module requires careful removal of the interior mirror mounting cover, disconnecting the sensor wiring plug, and release catches to remove the module, refitting being the reverse of removal. The seat heating module is accessible from the underside of the front seats, so the seat must then be raised or removed, and the center pin then prised up to remove the module, with refitting being a reversal of the removal process.