When it was introduced in 1995, the BMW Z roadster was a bold declaration. Right in its name was the implication: "Z" stood for "zunkenft," which means "future" in German. That future might have included beating its neighbor Porsche in its own backyard, challenging its new Boxter for the entry-level, open-air performance market. Then, much as now, the Z roadster countered the Boxter's mid-engine poise with pure, brute power -- and maybe that was the "future" BMW was talking about.
Open the hood of your BMW. Use the enclosed metal prop to hold the hood up as you work. Locate the diagnostic data port. It looks like a giant black screw cap, and it is located on the right side of the hood near the strut tower.
Open the cap, and inspect the interior. There should be 20 small holes and one larger hole in the center with a pointed "peak" in the middle. You want pins No. 7 in the connector. If you point the peak in the center hole straight up, Pin 7 is at the 6 o'clock position on the bottom-outer row. If you look closely at the connector, you may see tiny numbers denoting the pin next to each hole.
Cut a length of 12-gauge jumper wire long enough to reach from the connector to one of the studs on the strut tower. Strip approximately 1 inch of insulation from one end of the wire with wire strippers. Twist the wire with your fingers. Wrap the bare wire around one of the strut tower studs, and spin a nut down over it. Tighten the nut down with a wrench or socket to ensure a solid ground.
Strip about 1/2-inch insulation from the other end of the jumper wire, and twist the wire strands together with your fingers. Turn the car on, but only turn the key enough to start the electrical systems in the car and not the engine.
Push the bared end of the grounded jumper wire into the No. 7 pin hole identified earlier, and count to four. After exactly four seconds, quickly pull the wire out of the pin port. If you leave it in for 10 seconds or more, the computer will reset all of other service intervals as well. Check the oil light to see if it has turned off. If it hasn't, try the process again. Reinstall the port cap when you're finished.
