BMW have a number of options for the 5 and 7 series vehicles stereo and advanced functions (sat nav etc). What is less well known is the inter-compatibility of component items. Now before we go any further, the ultimate responsibility for any purchase and compatibilty remains with the buyer so if you are in any doubt, check as these can be expensive mistakes to make.
BMW monitors come in two sizes 16:9 widescreen and 4:3. Both have the ability to display the car's on-board computer and both are driven by the equipment located in the trunk (boot) space on the nearside. This guide DOES NOT address any issues with the 16:9 screens.
The 4:3 monitors can be used from virtually any car (left or right hand drive) and from virtually any age. However, you cannot place a 16:9 monitor into a 4:3 console - it may sound stupid to say it, but there will be people who try it! You cannot put a LHD console in an RHD car, but you can put a LHD monitor into a RHD console.
In order to replace the monitor, you will have to remove the entire centre stereo system from the dashboard. To do this, you need to drop the glovebox and then remove the dashboard trim above the glovebox and the trim to the right of the stereo system. Next, you need to remove the console bezel by removing two screws at the top of the unit and a single screw underneath the bezel. These are simple cross-heads. The centre stereo is held in place by four cross-head screws. Remove these carefully and then slide the assembly out enough to remove the two plugs from the rear of the stereo and the monitor. Once removed, you need to remove the black plastic bezel that holds the controls for the casette, radio and the surround for the monitor. These are Torx 8 screws (4 of). At the rear of the monitor, you may find a warranty sticker. When this is removed, you will see the words 'void' so beware - if you have a warranty, removing this removes that! Under the sticker is a large cross-head screw, remove this. At the top are two others, remove these and the monitor is now free to slide out.
At this point, it is probably a good idea to make sure that your replacement monitor is working. Plug the monitor cable into the rear of the new unit and switch on the ignition. If all is well, you should get a display, if not, then either your new monitor is not working, or the video unit in the rear of the car is bust. Assuming all is well, re-installation is simply the reverse of taking it out.
Monitors from BMW are not cheap (around £1,000 or more) so eBay is a very good place to seek out replacements, however, watch out for the sources and the conditions of the units. If someone advertises as 'untested' or 'broken' then be sure that the price reflects this. Those people with moderate or high electronics skills can repair these units, but most cannot. The equipment in the rear of the 5s and 7s is as important as the display equipment and if you replace items such as the DSP Amplifier, Dashboard clocks, Sat Nav, Video Module etc, you will almost certainly have to go to a BMW dealer to get the car re-programmed to make these devices work. Finally, if you have a car that suffers from 'pixelation' of the display consoles, then there are web sites that can help you see if these are real faults or simply age-related. Before you try any DIY work on these cars, it is safer to pay a little to get a BMW dealer to check out the severity of electronic issues as you could spend a fortune replacing parts unnecessarily.