Network, generic (extended)

U3019 Control Module Input Power Circuit B/C Correlation

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

U3019 pairs the second and third supply of a module and reports that they drift apart. The one published use comes from GM's electric brake booster module in the 2016 and 2018 hybrid tables (16OBDG02, 18OBDG01). There, one voltage sensor watches the booster circuit supply and a second one the supply of the motor driver; the module divides the two readings and sets U3019 when the ratio rises above 1.321 or falls below 0.766 for 2 s while running or shutting down. GM describes this as a check for drift of the voltage divider, so besides a weak feed a measuring fault inside the module is a real candidate. The code is Type A, meaning MIL on the first trip, and it passes after about 5 s with ignition on. Because the booster supports braking, expect a brake warning and possibly reduced assist.

Likely causes

Voltage loss on one feed from a corroded fuse, terminal or splice
Drift of the voltage divider or sensor inside the module
Motor driver supply sagging under load from a faulty booster motor stage

Symptoms

  • MIL and brake system warning on the first trip
  • Reduced or harder brake pedal assist
  • Often stored with input power low or high codes of the same module

Repair estimate

DifficultyHardWorkshop job
Parts and labour€20–1,500
Time0.5–3 h

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

Parts involved

module power bmodule power cbrake booster module

Related codes

U3018U3007U3013U3505U3509

References: gsi.ext.gm.com, gsi.ext.gm.com.