Network, generic (extended)

U3013 Control Module Input Power C Circuit/Open

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U3013 extends the input power family to a third feed, C, and reports it as missing or open. It only exists on modules with at least three separately fused supplies, such as large body or brake units. No manufacturer documents U3013 publicly, and nothing defines which pin is C; that is up to each maker's wiring. The detection principle can be taken from GM's brake module, which compares two battery feeds and flags one as open when it drops to about half of the other for 75 ms (U3006/U3007). CARB requires electronic inputs that the OBD system relies on to be checked for circuit faults, which is the basis for such checks. In practice a single blown fuse, a pushed-out pin or a weak battery is behind it; if C and D appear together, look for a shared fuse or a supply common to both.

Likely causes

Blown fuse in the feed C path
Pushed-out pin, corroded terminal or broken wire on supply C
Weak battery or voltage dip during cranking

Symptoms

  • Part of the functions of the affected module dead
  • Lost communication codes in other modules if the unit shuts down

Repair estimate

DifficultyMediumDIY possible
Parts and labour€10–300
Time0.3–2 h

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

Parts involved

module power cfuse

Related codes

U3014U3006U3007U3019

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