It started out with the rear hatch opening intermittently then went to the rear wiper stopping right after it starts then the 3rd brake light went out now the cruise disengages when headlights are on and after a minute or so goes into reduced power mode and obd port is not accesible. Can anyone help with ideas.

 

Welcome
1st thing I would check is the positive battery cable connection at the underhood fuse box. Also, how old is the battery ? You should get it tested.

FYI. To help us help you, please include some info like model of HHR, how long you've had it and any repairs or problems that could be relevent.

 

The battery was replaced last year. It is an hhr ls

 

Most of those issues are in the hatch, you could take the interior panel off and inspect the harness.

The OBD2 port is on the same fuse as the power port(cigarette lighter).

Once you get the OBD2 port going again, you should be able to get the codes read for free at your nearest auto parts store, and then the diagnosis of the reduced power can begin.

 

Perhaps a battery lobotomy is in order.