Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

2004 Mazda MX-5 Miata Base, AutomaticFACTORY OEM SERVICE PROCEDURE

GND Circuit Inspection

Turn the ignition switch to LOCK.
Disconnect the PCM connectors.
Inspect for continuity between the PCM GND terminals and body GND using an ohmmeter.
- If not as specified, repair the related harnesses for open circuit.
Fig 1: Identifying PCM Ground Terminals
Courtesy of MAZDA MOTORS CORP.

Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.

Shop Manual-Ready Tools Compare Repair Quote Quote Shield Pro

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.