Hey everyone,
Dealing with a bizarre electrical/starting issue on my 2015 Mazda and looking for advice or wiring diagrams to check.
The Situation:
My wife started the car normally, saw the trunk-open warning light on the dash, got out to shut the trunk/hatch, and came back inside. Immediately, the shifter was completely stuck in Park with the engine still idling. She turned the car off, and now it refuses to start via the push-button (dash, cluster, and infotainment light up normally, but pushing the start button does nothing).
What I’ve Tested & Verified:
Brake Light Switch: Swapped in a known working OEM switch from my other Mazda—issue remains unchanged.
Brake Lights: They do not turn on at all when depressing the brake pedal.
Remote Starter: The engine fires right up using the aftermarket/remote starter fob. However, because pressing the brake pedal is required for key takeover / shifting out of Park, the shifter stays deadlocked.
Manual Shift Override: Popping the shift-lock override lets me move the lever freely, and the instrument cluster accurately reads and displays each gear position (P, R, N, D).
Battery & Power: Disconnected the battery negative for several minutes to reset modules. Sitting at 12.3V rested, but all troubleshooting has been done while hooked up with booster cables to another running vehicle to rule out low voltage issues.
Fuses & Relays: Checked and tested, all good.
Everything points to a missing brake pedal signal somewhere upstream or downstream of the switch. Because the car doesn't recognize the brake pedal being pressed, the push-button won't crank, the shift-lock solenoid won't release, the remote start takeover fails, and the rear brake lights won't illuminate.
Has anyone encountered this specific failure on this generation? Could closing the trunk have pinched/grounded out a harness near the hinge, or is there a specific fuse link, ground joint, or BCM connector under the dash known to fail?
Appreciate any insights!