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2016 MAZDA MX-5 MIATA
2.0L I4•RWD•MANUAL•gas
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Repairs0Labor548Torque5629Fluid7DTC908Battery1Maintenance0Recalls0
P1780low severityPowertrain

Transmission Control Switch Circuit

on 2016 Mazda MX-5 Miata 2.0L I4 · RWD

What this code means

The PCM has detected a malfunction in the transmission control switch circuit. This switch allows the driver to select between different transmission operating modes such as sport, economy, or winter mode.

Symptoms

  • Check Engine Light
  • Transmission mode selection not working
  • Stuck in one transmission mode
  • Mode indicator light malfunction

Common causes

  • Faulty transmission mode switch
  • Wiring issue in switch circuit
  • Corroded switch connector
  • PCM input circuit fault
  • Switch mounting issue

Diagnostic steps

  1. Check transmission mode switch signal on scan tool while pressing switch
  2. Inspect switch connector for corrosion
  3. Test switch continuity in each position
  4. Check wiring between switch and PCM
  5. Verify PCM receives switch signal

Repair notes

Replace the transmission control switch if it does not change states properly.

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