Powertrain, generic (extended)

P2684 Actuator Supply Voltage C Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

Some transmission controllers power groups of solenoids through several internal high-side outputs; supply C is the third of these rails, after A (P0657) and B (P2669). P2684 reports an open load on it. GM's 2023 and 2024 TCM tables tie the code to high-side output 7 and test it while the module powers down: with the output off and a low-side driver on, the load should drag the line low, so a level above 40 % of battery voltage is remembered as an open load and reported after the next start, Type A. Ford's 2024 summary assigns P2684 to high side driver 7 of the TR9070 dual-clutch gearbox, and Ford's 2014 Boss 302S code list carries it as well. Whatever hangs on that rail stops working, so a default gear or limp mode is likely.

Likely causes

Broken wire or loose terminal between the module output and the supplied solenoids
Corroded or unseated transmission connector or internal lead frame
High-side output inside the controller defective

Symptoms

  • Transmission in default gear or limp mode
  • MIL on after restart
  • Several solenoid circuit codes stored together

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,500
Time1–5 h

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

Parts involved

actuator supply ccontrol modulewiring harness

Related codes

P2685P2686P2669P0657P26E7

References: gsi.ext.gm.com, gsi.ext.gm.com, fordservicecontent.com, performanceparts.ford.com.