Ignition Lock Replacement

by Jeffrey W. Baker - jwbaker@acm.org 

This article describes the procedure for replacing the ignition lock in your 2000 Mazda Miata. You might need to do this if someone tries and fails to steal your car, or if the switch stops working. The procedure involves removing the air bag, steering wheel, and combination switch, cutting off the old ignition switch, and mounting a new one. The procedure takes from one to two hours.

Tools you will need


  1. Unplug the battery

    Use the 12mm wrench to remove the negative cable from the battery. You must do this to remove power from the air bag, and to eliminate the risk of electrical shock. The battery is in the trunk on the passenger side.

  2. Remove the steering column trim

    Remove the trim that runs from behind the combination switch to the foot well. It is secured with two Phillips screws on the bottom. Remove them and pull the trim down. Set aside.

  3. Remove the combination switch trim

    The combination switch cowl breaks apart in the middle. Gently remove the top piece by grasping it in the stalk cut-outs and lifting up. The bottom piece is secured with three Phillips screws. Remove them, and set aside.

  4. Remove the air bag

    Be very careful when removing the air bag. It is explosive. Remove the two rubber screw covers on each side of the steering wheel. Use the 12mm socket wrench to remove the two screws which hold the air bag to the steering wheel. Lift the air bag out of the steering wheel a few inches, and disconnect the yellow connector. Set the air bag face up away from your work area.

  5. Remove the steering wheel

    Use the 21mm socket to remove the nut from the steering wheel. Mark the steering wheel and the shaft, so you can get the steering wheel back on straight. Set it aside.

  6. Remove the combination switch

    The combination switch is attached to the ignition switch with three Phillips screws. Remove them and disconnect the two electrical connectors on the bottom rear. Beneath the steering column is a nylon hold-down that secures the wiring trunk. You will need to free the hold-down before you can remove the combination switch. Rest the combination switch in the driver's foot well.

  7. Cut the ignition switch off

    The ignition switch is held on by two screws from the top. The screw heads are broken off so they look like two domes. Use your Dremel tool to cut a deep slot in each screw perpendicular to the steering column. You will also have to cut some material from the switch, but you are going to throw it away so don't worry. When you have cut a good, deep slot in each screw, use your offset screwdriver to remove the two screws. Remove the electrical connectors and throw away the ignition switch.

  8. Clean the work area

    Thoroughly clean the work area with wet rags. Make sure to pick up as many metal filings as possible from the steering column and instrument panel. Finish with dry rags.

  9. Mount the new ignition switch

    Mount the new ignition switch. The steering column is notched to locate it. Secure it by alternately tightening each screw 1/4 turn with the 12mm wrench until the screw heads break off. This doesn't require much torque. Attach the electrical connectors. Reattach the battery power and make sure you can start the car with the new switch. Remove battery power once again.

  10. Mount the combination switch

    Attach the combination switch with the three screws. Attach the electrical connectors, ensuring that the yellow air bag connector is properly seated. Reattach the nylon hold down under the steering column.

  11. Attach the steering wheel

    Align the marks on the steering wheel and the steering column. Thread the yellow air bag connector through the slot. Tighten the nut onto the shaft with the 21mm socket. 20 ft-lbs should be more than enough torque. Attach the electrical connector for the horn.

  12. Attach the air bag

    Connect the yellow electrical connector for the air bag and ensure that it is seated properly. Place the air bag in the steering wheel. Tighten the screws on both sides of the steering wheel with the 12mm socket, and replace the rubber screw covers.

  13. Replace the trim

    Replace the trim around the combination switch and the lower steering column.

  14. Restore battery power

    In the trunk, attach the negative battery cable and tighten with the 12mm wrench.

  15. Test

    Test the function of the ignition, the steering wheel lock, and the combination switch. Make sure that the air bag warning lights display according to the owner's manual.

  16. Drive your Miata
This artice written by Jeffrey W. Baker on 12 March 2001.