What does code P1780 mean?

P1780 · Mercedes-BenzModulation Pressure Switchover Valve ATCC Y34 Or Upshift Delay Switchover Valve ATCC Y35

P1780 on Mercedes-Benz vehicles indicates that the transmission control module has detected an electrical fault in the circuit for either the modulation pressure switchover valve (Y34) or the upshift delay switchover valve (Y35), both part of the automatic transmission control (ATCC) system. The computer monitors the valve's electrical circuit and sets this code when the expected current or voltage is outside the normal range, typically due to an open, short, or faulty solenoid.

SystemPowertrain

Code typeMercedes-Benz specific

SeverityMedium

Fix difficultyIntermediate

AreaTransmission

Guidance is general and written for Mercedes-Benz vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.