GM Service Manual Online
For 1990-2009 cars only

The hybrid drive motor battery has two venting systems. One for hybrid battery cooling air and one for venting of possible gases from the hybrid battery vents. The hybrid batteries vent system connects all the battery vents to a rubber manifold that exits the hybrid drive motor battery through a single hose and is vented through the floor panel of the vehicle.

Air cooling

The drive motor generator battery is cooled by a vent fan motor. The vent fan motor and vent fan motor relay are located inside the drive motor battery assembly. B+ to the vent fan is provided from vent fan relay when the battery energy control module (BECM) supplies a ground to the relay. The battery vent fan draws the air through the batteries to cool them. There are several foam seals internal to the drive motor generator battery in order to prevent air leaks. The exhaust air exits from hybrid drive motor generator battery in the rear and is routed through a duct into the floor panel of the vehicle. The hybrid battery air inlet temperature sensor is located on the inlet air duct for the hybrid battery fan, and the battery air outlet temperature sensor is located in the air passage above the hybrid batteries. These sensors are used by the battery energy control module (BECM) to determine air flow. Refer to Drive Motor Generator Control Module Description and Operation .

Electrolyte venting

Each of the 40 hybrid batteries has a vent for electrolyte gas that is located on the top of each battery. The hybrid batteries vent system connects all of the 40 hybrid battery vents to a rubber manifold. The vent exits the hybrid drive motor generator battery through a single hose in the rear and is vented through the floor panel of the vehicle. These vents are mechanical and will only open when a predetermined amount of internal battery pressure is reached.