How do I fix the starter clicking problem on a Mazda RX-7 FD?

The "click, click, start" issue is a very well-known problem on the FD RX-7. The root cause is a significant voltage drop along the long factory starter circuit (from the battery to the ignition switch, through the clutch switch, through the security relay, and finally to the starter). Over time, resistance builds up in these components, resulting in insufficient voltage reaching the starter solenoid to engage it.

Here are the most effective ways to permanently fix the issue, listed in order of popularity and success rate.

1. Install a Starter Booster Relay (Difficulty: Moderate)

This is widely considered the best and most permanent fix. A booster relay routes full battery voltage directly to the starter solenoid, completely bypassing the resistance of the aging factory wiring.

• Pre-made Kits: You can purchase plug-and-play kits like the Banzai Racing or Pettit Racing starter boosters ⁴.
• DIY Method: You can build your own using a weather-tight 30/40A SPDT relay. Recommended parts include an Omron G8JN-1C6T-F-DC12 relay with a BR05-SR PW5-1 socket, or a waterproof Hella relay (Part #007794301). Use 14-gauge or 12-gauge wire for the power/ground lines and 16-gauge for the signal wire ².

2. Bypass the OEM Security Relay (Difficulty: Easy)

The factory H302 security relay is a common source of resistance. It is located behind the driver’s side kick panel near the dead pedal.

• Remove the relay and jumper the two thick wires (Black/Blue) together on the connector ².
• Alternative Direct Wire: Some owners run a new 10-gauge wire directly from the thick Black/Blue wire at this security relay plug straight through the firewall to the starter solenoid, reducing the length and number of connections in the circuit.

3. Clean or Secure the Ignition Switch (Difficulty: Moderate)

Corrosion or mechanical looseness in the ignition switch can cause a weak connection.

• Cleaning: Remove the steering column covers to access the switch. Take it apart and use a Dremel with a wire brush to polish the internal copper contact plates ¹.
• Securing: Check if the white plastic cylinder housing the switch is twisting when you turn the key. The single top retaining screw can sometimes allow it to shift, preventing solid contact. Applying pressure or securing the switch housing firmly (some use zip ties as a makeshift clamp) can immediately restore a strong signal to the starter ².

4. Clean or Bypass the Clutch Interlock Switch (Difficulty: Easy)

The FD has two clutch switches; the starter interrupt switch (Part # 66-4D0) is located at the bottom of the pedal travel.

• Check to ensure the small rubber bump stop on the pedal that depresses this switch hasn't crumbled and fallen out.
• If the switch itself is failing, you can pry the top off to clean the internal metal slider and spring, or temporarily bypass it with a jumper wire. Note: Bypassing this removes the safety feature preventing the car from starting in gear.

5. Clean Starter Solenoid Contacts (Difficulty: Easy)

Safety Warning: Always disconnect the battery before working near the starter to prevent accidental shorts.

• Remove the wires attached directly to the starter solenoid. Use 400-grit sandpaper to clean the contact rings until you see bare, shiny metal. Over-tightening these bolts can easily tear the soft copper threads out of the solenoid, so reinstall them carefully ².