P0780 – Gear selection -shift malfunction

John Kershaw

By John Kershaw (Contact Me)
Last Updated 2016-01-17
Ed.D, PhD Philosophy, BSME

Trouble CodeFault LocationProbable Cause
P0780 Gear selection -shift malfunction Wiring, TR sensor, shift solenoids, transmission mechanical fault

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What Does Code P0780 Mean?

DTC P0780: The TCM (Transmission Control Module) or PCM (powertrain control module) monitors the transmission mechanical shifting through various sensors. This malfunction is detected when the transmission does not shift as instructed by the TCM. This is not caused by electrical malfunction (circuits open or shorted) but by mechanical malfunction such as control valve sticking, improper solenoid valve operation, etc.

NOTE: Whenever diagnosing a 700 series DTC (Diagnostic Trouble Code) with a transmission, transfer case or other driveline components, check for a DTC under chassis and body systems, not just under “P” or powertrain/engine or emission control type codes. Module communications DTCs are “U” codes. These are most often found when looking for DTCs under chassis or body systems. Chassis related codes are labeled “C” and body system related codes are labeled “B” codes and these can cause drivetrain issues if they affect a sensor that is also used by the heating and air conditioning system.

The TCM or PCM has detected an abnormality in shift procedure. The TCM/PCM controlled automatic transmission uses shift solenoids to manage the transfer of fluid between hydraulic circuits and actuate a change in transmission gear ratio. Varying gear ratios are needed to increase and decrease vehicle speed, maximize engine performance, and optimize fuel efficiency.

780

What are the common causes of code P0780 ?

  • Low transmission fluid, dirty or contaminated transmission fluid
  • Hydraulic blockages inside the internal transmission fluid passages
  • Mechanical internal transmission failures
  • Defective shift solenoid
  • Shifting solenoid valve harness is open or shorted
  • Shifting solenoid valve circuit poor electrical connection
  • Defective PCM or TCM

What are the symptoms of code P0780 ?

  • MIL (Malfunction Indicator Lamp [Check Engine & Service Engine Soon])lights on with stored historical P0780
  • Harsh shift, failure to shift, failure of the transmission to shift from (or into) any particular gear.
  • Slippage, transmission overheating
  • Decreased fuel efficiency
  • Other shift solenoid codes often accompany this code
  • TCM/PCM may also enter “limp-in” mode when this code is stored.

Codes Related to P0780

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