Powertrain, generic (extended)

P2D58 Generator B Mechanical Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

P2D58 reports that generator B, the second alternator of a dual charging system, does not deliver as commanded for mechanical reasons, most often because its drive slips. Such machines often sit on their own belt and idler. GM's customer satisfaction program N192255140 for 2019 Silverado medium-duty trucks with secondary generator option KHB shows how sensitive that mounting is: a bolt that missed its clamp load could work loose, so dealers fitted a new bracket for the A/C compressor together with the idler and inspected the belt. No manufacturer documents P2D58 publicly. Infineon's LIN regulator TLE8881-3 recognises a broken belt or stalled alternator when the phase signal stops swinging above a cut-in speed. Check belt, tensioner, pulley and bearings first. Generator A: P065C.

Likely causes

Worn, glazed or oil-soaked drive belt slipping
Weak tensioner or loose idler pulley mounting
Stiff alternator bearing or faulty overrunning pulley

Symptoms

  • Charge warning lamp, low charging voltage
  • Belt squeal or noise from the second alternator

Repair estimate

DifficultyEasyDIY possible
Parts and labour€30–500
Time0.5–2.5 h

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

Parts involved

generator bdrive beltbelt tensioner

Related codes

P2D57P2D59P065CP065B

References: static.nhtsa.gov, infineon.com.