P1780low severityPowertrain
Transmission Control Switch Circuit
on 2020 Mazda Mazda3 2.5L I4 · FWD
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
- Check transmission mode switch signal on scan tool while pressing switch
- Inspect switch connector for corrosion
- Test switch continuity in each position
- Check wiring between switch and PCM
- Verify PCM receives switch signal
Repair notes
Replace the transmission control switch if it does not change states properly.
Other Powertrain codes on this vehicle
P0001
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P0002
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P0003
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P0004
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P0010
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P0011
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P0012
Intake Camshaft Position Timing Over-Retarded Bank 1
P0013
Exhaust Camshaft Position Actuator Circuit/Open Bank 1
P0014
Exhaust Camshaft Position Timing Over-Advanced Bank 1
P0015
Exhaust Camshaft Position Timing Over-Retarded Bank 1