Powertrain, generic (extended)

P285F Shift Fork B Actuator Circuit/Open

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

With P285F the module reports that the drive circuit of the fork B actuator is open: current cannot flow when the motor or valve is energised. In Ford's DPS6 dual-clutch box, the second shift drum is turned by its own three-phase motor and places the forks for reverse plus 2nd, 4th and 6th; an open motor circuit there is P285F and requests the MIL. The 2012 Ford summary prints that paragraph under the heading of drum A again, but its codes and gear list clearly belong to drum B. Further checks on the same motor are P2836 for the driver chip, P283A for the hall pattern and P2837 when the drum position becomes unreliable. A car with P285F usually loses reverse and the even gears, so manoeuvring may become impossible.

Likely causes

Fork B actuator connector loose or with spread terminals

Open wire in the harness to the fork B actuator

Burnt or broken winding in the fork B motor

Symptoms

No reverse gear, even gears missing
Engine lamp and gearbox fault message
Car drives only in 1st, 3rd and 5th with large rpm steps

Repair estimate

DifficultyHardWorkshop job

Parts and labour€100–1,500

Time0.5–4 h

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

Parts involved

shift fork actuator bwiring harnesstcm

References: newtonnet.co.uk, performanceparts.ford.com, law.cornell.edu.