P0BAC Possible Causes
- Defective hybrid/electric vehicle battery
- Faulty hybrid/electric vehicle battery interface control module
What Does It Mean?
How to Fix P0BAC Code
Check the “possible causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
P0BAC Symptoms
Possible symptoms
Check engine light illuminated (or service engine soon warning light)
P0BAC Meaning
The hybrid/electric vehicle battery contains 288 cells. Groups of three cells are welded together in parallel. There are a total of 96 cell groups in the hybrid/EV battery pack. These cell groups are electrically connected in series. Each individual cell group is rated at 3.7 V, for a nominal system voltage of 355 V DC. The battery cells are also grouped into three sections. The first 90 cells/30 cell groups make up battery section one. This section is adjacent to the hood and contains batteries 67 to 96. Battery section two is located behind section one. It consists of 72 cells/24 cell groups and contains batteries 43 to 66. The battery cross-section is section number three, it consists of the remaining 126 cells/42 cell groups and contains batteries 1 to 42. The three battery sections are individually repairable components.
The battery energy control module monitors the voltage of the 96 battery cell groups via the four hybrid/EV battery interface control modules. Voltage sensing circuits are attached to each individual cell group, and these sensing circuits terminate at a connector located on the top surface of the battery section. A serviceable auxiliary battery wiring harness connects this connector to a hybrid/EV battery interface control module, also located on the top surface of the battery section. The hybrid/EV battery interface control module encodes the voltage reading and transmits it to the battery energy control module via the battery control harness. There is one hybrid/EV battery interface control module located on battery sections one and two, and two hybrid/EV battery interface control modules associated with battery section three. The hybrid/EV battery interface control module, battery energy control module wiring harness, auxiliary battery wiring harness, and battery energy control module are all considered serviceable components.
The battery energy control module will determine when a fault condition is present. System diagnostics and status are communicated from the battery energy control module to the hybrid/EV powertrain control module 2 via serial data. The hybrid/EV powertrain control module 2 is the host controller for diagnostic trouble code information.