Powertrain, generic (extended)

P2BC7 Battery Charging System Positive Contactor B Control Circuit/Open

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

P2BC7 concerns the coil drive line of positive charging contactor B, not its main contacts: the module compares its command with the voltage and current it measures on that line and sets the code when the line is broken or the driver that does not follow. No manufacturer documents P2BC7 publicly. GM's test for the twin code of contactor A (P0D0A) on the Chevrolet Volt shows the method: with the driver off, more than 4 V on the output means an open, and with it on, a coil current under 57 mA counts as open too; the code needs 40 bad readings in a window of 50, taken every 12.5 ms. Monitoring of charging hardware on plug-in models is a CARB requirement. Usual causes: broken wire, loose plug, open coil. Range/performance, low and high are P2BC8–P2BCA, the minus side P2BCE. The charging mode behind contactor B is lost.

Likely causes

Control wire or connector to contactor B interrupted
Coil of positive contactor B open
Driver stage in the control module defective

Symptoms

  • Charging via the contactor B path not possible
  • Charging fault indication

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 pos contactor bwiring harnessbms

Related codes

P2BC4P2BC8P2BC9P2BCAP2BCEP0D0A

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