The BMW 7 series has many convenience features. However, after time some of these can become out of date. The 1998 BMW 740i, for instance, has a cassette/CD player that some drivers may find suitable for their needs. Others may want more modern conveniences, requiring installing a new stereo unit. Replacing the stereo in a 1998 BMW 740i will require some mechanical experience and isn't recommended for novices.
Open the vehicle's hood and locate the battery. Use an adjustable crescent wrench to remove the cable connected to the negative battery terminal. Wrap the metal ending with a cloth and lay to the side.
Locate the two trim squares positioned on each side of the stock stereo. Wrap a slot-head screwdriver in a clean shop rag and gently pry off the trim squares. Remove the two exposed screws on each side of the stereo using a Phillips screwdriver. Gently remove the stereo by pulling it away from the console.
Remove all the wires connected to the stereo as well as the antenna plug. Install the installation brackets found in the aftermarket stereo trim kit to the new stereo unit. Plug the aftermarket wire harness and antenna plug into the back of the new stereo. Connect the original wire plug into the female end of the after-market wire harness.
Gently route the wires behind the unit into the dashboard opening. Slide the new stereo unit into the opening, ensuring that the wires aren't pinched or caught between the bracket rails. Secure the new unit using the supplied screws. Clip the new trimwork included in the aftermarket stereo trim kit to fill in the exposed spaces in the dashboard.
Remove the shop cloth from the battery cable. Reinstall the cable on the negative battery terminal and tighten it using the adjustable crescent wrench. Ensure that the cable is properly tightened by using your hand to attempt to twist it. Tighten the mount until the cable cannot be twisted.
