How to Upgrade a Stereo in a 1989 BMW 325i


1. Disconnect the battery from the vehicle by removing the nuts that secure the cables with a wrench.
2. Examine the dash of the vehicle. Look for grooves between the dash and the body of the car around the radio. The dash is a separate piece that can be pried off. Insert a flat head screwdriver between the dash and the radio. Gently pull the dash off of the body. Repeat this process every few inches in the groove to loosen the entire dash panel. Once the panel is sufficiently loose, it can be removed by hand.
3. Remove the screws that secure the radio in place with a flat head screwdriver. These screws are located on either side of the radio. Pull out the stock radio. Disconnect all of the wires from the back of the radio then set it aside.
4. Purchase a wiring harness for the new head unit. The wiring harness will connect the previous stereo's connector wires to the new head unit. The old wires can be hard-wired to the new head unit. The wire color codes for the 1989 BMW 325 are:Constant 12V+: Red/WhiteSwitched 12V+: Purple/WhiteGround: BrownAntenna Trigger: WhiteFor the front speakers (5 1/4-inch kick panels)Left Front (+):WhiteLeft Front (-):BlackRight Front (+): WhiteRight Front (-): BlackFor the rear speakers(5 1/4-inch side panels)Left Rear (+):WhiteLeft Rear (-): BlackRight Rear (+): WhiteRight Rear (-): Black
5. Connect the BMW's stereo wires to the new head unit. Insert the new head unit into the body of the car and screw it in. Reattach the dashboard. Reconnect the battery. Turn on the car and test the stereo.