Network, generic (extended)

U350C Control Module Cooling Fan Circuit/Open

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

U350C reports that the fan built into or attached to a control module draws no current, or its circuit is open, at the moment the module switches it on. Some electronics carry their own blower: on the 2021 Toyota RAV4 Prime the plug-in charger has a fan with a speed sensor (bulletin T-SB-0021-21, code P1CE931), and the central infotainment unit of the Karma Revero has one under a shroud (TB-24-94-01). For electrical parts that cool inverters and traction batteries, CARB requires circuit and function monitoring. No maker documents U350C itself. With the fan dead, the module heats up and may cut its own output, charge more slowly or shut down. Shorts are split off into U350D/U350E; U350F covers a fan that is wired correctly but runs wrong.

Likely causes

Fan motor winding or brushes open
Fan plug loose or not latched after the module was removed
Broken fan supply or control wire
Fan output stage inside the module failed open

Symptoms

  • Module fan silent when it should run
  • Module overheats, reduces output, charges slower or restarts
  • Temperature warning or function message for the affected module

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€40–600
Time0.5–3 h

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

Parts involved

module cooling fanfan wiring

Related codes

U350DU350EU350FP0480

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