Network, generic (extended)

U301A Control Module Wake-up Circuit A/Open

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

A wake-up circuit is a separate wire that rouses a sleeping module without bus traffic, for example when a charge cable is plugged in or another controller needs it. U301A reports that line A has lost continuity, so no valid signal reaches the input. Ford's 2019 hybrid OBD summary shows such a line in use: the battery energy control module relies on a hardwired charge wake-up signal before it runs its charging and contactor checks. No manufacturer documents U301A publicly. GM's PIT6198 for 2019–2022 Silverado and Sierra shows the consequence of a lost wake input at the ECM (circuit 5985, about 12 V with the BCM awake): other modules report U0100 and the service engine lamp comes on, with possible shift complaints. An open wake line usually means the module stays asleep or joins late.

Likely causes

Broken wake-up wire or pushed-out connector pin
Corroded or loose contact at the sending or receiving module
Sending module or charger not driving the wake-up output
Blown fuse in a supply-fed wake circuit

Symptoms

  • Module does not respond, other modules report lost communication
  • Charging or a function that needs the wake-up does not start

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–600
Time0.5–3 h

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

Parts involved

wakeup circuit awakeup wiring

Related codes

U301BU301CU301DU301EU3012

References: fordservicecontent.com, static.nhtsa.gov, law.cornell.edu.