Car Stereo Radio Wiring Diagram and Wire Colors – 1999 BMW Z3 Whether your an expert installer or a novice enthusiast with a 1999 BMW Z3, an automotive wiring diagram can save yourself time and headaches. One of the most time consuming tasks with installing a car stereo, car radio, car speakers, car amplifier, car navigation or any mobile electronics is identifying the correct wires for a 1999 BMW Z3. The Modified Life staff has put their heads together 1999 BMW Z3 OE Wiring Harnesses & Stereo Adapters — BMW Z3 1999, Factory Replacement Wiring Harness by Metra®, with OEM Radio Plug. For factory stereo. This high-quality Metra wiring harness is just what you need to replace your defective or aged factory wiring harness.