Theory Of Operation

Plug-in Hybrid Electric Vehicle (PHEV) and Electronic Stop/Start (ESS) equipped vehicles monitor the hood ajar status using two switches. Hood Ajar Switch 1 is integrated into the Hood Latch and is hard wired to the Body Control Module (BCM). The signal is sent to the Powertrain Control Module (PCM) over the CAN Bus. Hood Ajar Switch 2 is hard wired to the PCM. If the PCM detects that either switch is in the open position or is faulted for any reason during a normal drive cycle, ESS will be disabled for the remainder of the drive cycle. This condition will cause the engine to default to a running state on both PHEV and ESS equipped vehicles.