How do I replace the ignition switch on a 1984 Mazda RX-7 FB GSL-SE?

Replacing the ignition switch on a 1984 RX-7 is a straightforward job, but sourcing the correct part is usually the biggest hurdle. The plastic internal latches inside these original switches are notorious for becoming brittle and completely disintegrating over time ¹.

Difficulty: Easy
Safety Warning: Disconnect the negative battery terminal before starting to avoid shorting any unfused circuits under the dash.

1. Sourcing the Part

You need the electrical switch that mounts to the back of the key lock cylinder, not the keyed cylinder itself.

• The correct OEM part number for 1984–1985 models is FA54-66-151 ².
• Do not buy a generic "race use only" switch from Amazon, as they lack the necessary circuits to run your accessories and will require heavy modification ².
• Because these are often out of stock at standard auto parts stores, your best bets for a direct plug-and-play replacement are Atkins Rotary, RockAuto, the RX7Club marketplace, or the Australian rotary specialist site PacPerformance.com.au ¹.

2. Replacement Procedure

The context doesn't detail the physical teardown, so the following is standard practice for the FB chassis.

1. Remove the steering column covers: Look underneath the steering column for the Phillips-head screws holding the plastic clamshell together. Remove them and separate the top and bottom halves to expose the ignition lock assembly.
2. Disconnect the wiring harness: Follow the pigtail down from the back of the ignition switch to the main harness connector and unplug it.
3. Remove the switch: The electrical portion of the switch is held onto the back of the heavy metal lock cylinder housing by one or two small screws. Remove them and pull the switch straight out. If yours has disintegrated, be sure to clean out any broken plastic debris from inside the housing.
4. Install the new switch: Slide the new switch into the housing, ensuring the slot lines up with the tang on the back of the lock cylinder. Reinstall the retaining screws (just snug them by hand, no specific torque spec is needed for these small screws).
5. Route and reconnect: Route the wiring exactly as it was and plug the connector back in.

3. While You're In There

While you have the column covers off, take a look at the brown plastic A-02 connector box right behind the ignition. This houses a fusible link (typically 10–15A) that protects the Black/Red (B/R) start wire going to your starter solenoid; verify it looks intact while you have easy access ⁴.

If you find any previous owner's wiring hacks under the dash during this process, fix them properly. Never use wire nuts for automotive wiring—they will vibrate loose. Always solder and heat-shrink your connections ⁵.

Reconnect your battery, verify the car cranks and that your accessories (radio, wipers, dash lights) work in the "ON" position, then button up the plastic column covers. If you need a wiring diagram to trace out any specific electrical gremlins, the factory service manuals for the FB are available for free at Foxed.ca ².