Network, generic (extended)

U350A Control Module Input Power C Circuit High

Check engine lightOn
EmissionsNot relevant
Drive cycleRequired
Limp modePossible

U350A is the overvoltage code for supply C. GM's electric brake booster (2016–2019 hybrid tables) logs it when voltage sensor 2 on the motor driver supply exceeds 19.8 V for 90 s at speeds above 4 mph, Type A, so a single failing trip lights the MIL. The limit is higher than the 16 to 18 V thresholds used for feeds A and B because the motor stage tolerates more, yet a lasting excess is treated as serious since it threatens the power transistors. The pass condition is a straight drive over 3.1 miles or more. Such values rarely arise in a healthy 12 V system: think of a failed generator regulator or DC/DC converter, jump-starting from a 24 V source, or, with normal battery voltage, an internal sensing error.

Likely causes

Generator regulator or DC/DC converter overcharging
Jump start from a 24 V source
Faulty measurement of feed C inside the module

Symptoms

  • MIL and brake warning on the first trip
  • Brake assist reduced or switched off

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€20–1,200
Time0.5–3 h

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

Parts involved

module power ccharging system

Related codes

U3509U3508U350BU3506U3502

References: gsi.ext.gm.com, gsi.ext.gm.com, law.cornell.edu.