Powertrain, generic (extended)

P2BCF Battery Charging System Negative Contactor B Control Circuit Range/Performance

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

P2BCF points to a control circuit on negative charging contactor B that is neither open nor shorted yet still implausible: coil current, line voltage or switching time fall outside the window that belongs to the commanded state. No manufacturer documents P2BCF publicly, and no published GM table has such a check for a charging contactor coil. CARB asks for rationality checks in addition to circuit checks on plug-in charging components. GM's patent on diagnosing the battery disconnect unit shows the kind of evidence available: how the coil current rises after a brief pulse, held against a stored profile, separates a healthy contactor from a sluggish one. A shifted coil resistance, corrosion in the connector and a poor module ground are typical. Opens are P2BCE, low and high P2BD0/P2BD1, the plus side P2BC8.

Likely causes

Corrosion or contact resistance in the control connector
Coil resistance of negative contactor B shifted
Poor ground of the controlling module

Symptoms

  • Charging drops out or will not begin
  • Charging fault message from time to time

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–1,500
Time1–5 h

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

Parts involved

bcs neg contactor bwiring harnessbms

Related codes

P2BCEP2BD0P2BD1P2BC8P0D12

References: law.cornell.edu, patents.google.com.