Network, generic (extended)

U3010 Ignition Input Start

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U3010 concerns the start or crank request input, which should be active only while the key or button is held in Start. A module sets it when it sees a start signal outside a valid crank event, or misses one although the network reports crank. In GM's 2012 truck wiring manual the start position is the only one in which the run/crank line is active while the accessory line is off, so the start state is recognised from a combination of lines that must change together. No manufacturer documents U3010 publicly. The moment of transition is delicate: Ram found that the 2025 heavy-duty LED headlamp modules flag the run-to-start change as invalid (U300A-29) and treat it as harmless if stored only, which shows that a code logged exactly at cranking can be a software artefact rather than a wiring fault.

Likely causes

Worn start contact or push-button in the ignition switch
Start request wire open or shorted to voltage
Module software misreading the run-to-start transition
Supply dip during cranking upsetting the input reading

Symptoms

  • Engine does not crank or cranks with a delay
  • Code stored at each start with no further complaint

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–500
Time0.3–2.5 h

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

Parts involved

ignition inputignition switchignition wiring

Related codes

U300DU300AU300EP2533P0615

References: law.cornell.edu, gmupfitter.com, static.nhtsa.gov.