Network, generic (extended)

U3024 Control Module Input Power Circuit B - Ignition Input On/Start Circuit Correlation

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U3024 is the same plausibility test as U3023, but against the module's second battery feed, B: with the key in run or start, feed B and the switched ignition input should show about the same voltage, and a lasting gap points to a fault on one of the two paths. The code only makes sense on modules with two permanent feeds plus an ignition line. No manufacturer documents U3024 publicly. For guidance, GM's 2025 tables describe the A variant in engine and transmission modules: battery present, run/crank active, starter not engaged, and a difference above 3 V in most of 50 samples. If only U3024 is stored and not U3023, feed B itself is the more likely culprit, since a missing ignition signal would upset both comparisons. Effects depend on what feed B powers inside the module.

Likely causes

Blown fuse or damaged wire on battery feed B
Run/crank relay or ignition wire delivering too little voltage
Loose or corroded pin for feed B in the module connector
Faulty voltage sensing inside the module

Symptoms

  • Warning lamp or message, depending on the module
  • Loss of functions supplied through feed B

Repair estimate

DifficultyMediumDIY possible
Parts and labour€10–400
Time0.3–2.5 h

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

Parts involved

module power bignition input

Related codes

U3023U3007U3018U3505U3010

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