Network, generic (extended)

U3507 Control Module Input Power B Circuit Intermittent/Erratic

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

U3507 covers an unsteady supply B: the voltage is mostly in range but drops out or jumps for short moments. Since B often powers stages such as motors or valves, the dropouts typically appear when these draw current, for instance while braking or steering. GM's brake booster tables show that the module judges B over short and long windows (0.2 s up to 90 s); a fault that merely flickers fits neither the low nor the high code and counts as erratic. No manufacturer documents U3507 publicly. Suspect loose crimp contacts, worn fuse holders, corroded grounds and chafed wires, and test under load with a recording meter or scope. If U3505 or U3018 are stored as well, the feed has probably dropped out completely at times.

Likely causes

Loose crimp or worn fuse holder in feed B
Corroded ground point of the module
Chafed wire with intermittent contact

Symptoms

  • Brief function dropouts when power stages switch on
  • Code returns sporadically and is hard to reproduce

Repair estimate

DifficultyMediumDIY possible
Parts and labour€10–500
Time0.5–3 h

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

Parts involved

module power bpower wiring

Related codes

U3504U3505U3506U3503U3018

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