Powertrain, generic · Hybrid propulsion

P0DB9 Hybrid/EV Battery Cell Balancing Circuit D Stuck On

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

A stuck-on circuit D (P0DB9) drains group D continuously. The usual check is simple: does the switch state reported back equal the state the controller asked for? GM applies this on the eAssist battery for a related code, sampling every 200 ms and logging a Type B fault after 7 mismatches in 10. Here the reported state stays on while the command says off. Besides the voltage loss, the bleed resistor keeps warming its part of the module, which can upset temperature readings nearby. On Ford hybrids the code is real: the 2019 OBD summary checks circuit D for 0.1 s at each start, before the high voltage contactors close, against a 75 mV deviation of any of its six cells from the average. The broken-circuit case is P0DB8, the inactive case P0DBA.

Likely causes

Balancing transistor of circuit D shorted
Status feedback of the module wrong, switch actually fine
Drive output of the monitoring chip stuck on

Symptoms

  • MIL with battery warning
  • Group D cells and their local temperature deviating
  • Loss of charge while parked

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€300–4,000
Time2–8 h

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

Parts involved

hv battery cell balancing circuit dbms

Related codes

P0DABP0DB8P0DBAP0DBBP0DB5

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