Network, generic (extended)

U3508 Control Module Input Power C Circuit Range/Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

U3508 checks the plausibility of a third supply input, C. Only modules with large or separately protected loads have three feeds; in GM's electric brake booster (2016–2019 hybrid tables) C is the motor driver feed, measured by voltage sensor 2 and compared with feed B through U3019 (ratio outside 0.766 to 1.321). U3508 would apply if C is present but its value does not suit the operating state, for instance staying high while the motor draws current or departing from battery voltage, without crossing a hard limit. No manufacturer documents U3508 publicly; GM uses only the Low and High codes for C. Check the motor feed and its ground under load and look for related U3019 or U3013.

Likely causes

Resistance in the motor supply path of feed C
Poor ground of the power stage
Drift of the internal voltage divider

Symptoms

  • Reduced function of the motor-driven system
  • Correlation codes between feeds stored as well

Repair estimate

DifficultyMediumDIY possible
Parts and labour€10–600
Time0.3–2.5 h

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

Parts involved

module power cpower wiring

Related codes

U3509U350AU350BU3019U3013

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