Powertrain, generic · Transmission

P0766 Shift Solenoid D Performance/Stuck Off

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

A shift solenoid is an electrically switched valve in the valve body; the module checks whether its clutch follows the command by gear ratio, shift time or a pressure switch. P0766 means solenoid D is commanded on but its clutch does not follow. Ford checks gear ratio over 10 events (2012) or 3 (2020–23 and the 2023 diesel); on the 6F transmissions solenoid D feeds two clutches, so Ford recognises a solenoid fault when both fail, while a single clutch fault sets ratio codes. Ford's 10R80 bulletins list it with a leaking clutch cylinder; Dodge's Aisin AS6 uses it for solenoid 4. GM does not use P0766.

Likely causes

Clutch or brake of this circuit leaking or worn (piston seal, linings)
Shift spool or proportional valve sticking (dirt, debris)
Fluid level or quality
Pressure switch faulty (Allison, Aisin)

Symptoms

  • Upper gears (4th–6th) missing, or no reverse or engine braking in first (Ford)
  • Slip or engine flare on shifts
  • Limp mode
  • Check engine light

Repair estimate

DifficultyHardWorkshop job
Parts and labour€200–3,500
Time2–12 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

shift solenoidtransmission valve bodytransmission wiringtransmission control module

Related codes

P0767P0765P0768P0734P0771P0756

References: newtonnet.co.uk, fordservicecontent.com, fordservicecontent.com, static.nhtsa.gov.