Powertrain, generic · Hybrid propulsion

P0BC1 Hybrid/EV Battery Pack Cooling Fan Supply Voltage Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P0BC1 flags voltage on the battery fan feed when there should be none, or more than expected. GM documents it for the battery pack control module of its Two-Mode hybrid SUVs and pickups (Tahoe, Yukon, Escalade, Silverado, Sierra; 2012 and 2013 tables) as a welded fan relay: with the fan commanded off, a fan monitor voltage of at least 0.9 V in 10 of 20 samples at 100 ms sets it, provided the 12 V system is between 9 and 18 V and no fan circuit code (P0A81) is active. It is Type B, MIL after two trips. A stuck relay keeps the fan running with the vehicle off and drains the 12 V battery. The open and low cases are P0BBF and P0BC0; a fan that keeps turning without this fault is P0A83.

Likely causes

Fan relay contacts welded closed
Fan feed shorted to a constant battery voltage wire
Relay control output in the module stuck on

Symptoms

  • MIL on after two trips
  • Battery fan keeps running after the vehicle is switched off
  • Discharged 12 V battery after standing

Repair estimate

DifficultyEasyDIY possible
Parts and labour€15–250
Time0.2–1.5 h

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

Parts involved

hv battery cooling fan supplybattery cooling fan relaywiring harnessbms

Related codes

P0BBFP0BC0P0A83P0A85P0A81

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