HHR battery ground strap in trunk. Do any of you guys know exactly what is going on with that "thing" in the ground strap. There is a 50 amp fuse in a holder attached to the body beside the grounding wire but not part of it. Cannot find anything in my 09 Factory Work Shop Manual(s). Something to do with run-down protection ??

 

That little gizmo which goes by the name of part number 10306471, is a battery current sensor, and you correctly deduced that it is part of the run down protection circuit.

They have it fused in order to protect the vehicle in case of an overload or accidental reversed attachment of jumper cables. Even though you should always follow the instructions in your owner's manual and jump them from under the hood.

 

The Battery Current Sensor info can be found in the 2009 FSM at pages 11-109, 11-178, 11-217 & 9-592. A description can be found on pages 9-599 & 9-654. It goes to the BCM Connector #1, pins 63, 64 & 68.

I asked this question years ago and ChevyMgr answered in a post I cannot currently find.

That 50 Amp fuse at the battery is a fuse for the BCM and is not part of the Battery Current Sensor circuit. The large Red with Black tracer wire goes into the BCM on Connector #3, the big red connector in the middle of the BCM. The BCM also gets power from the underhood fuse box. Schematics for this 50 Amp Fuse can be found on page 11-7, 11-64 & 11-72.

Sorry this info is so cryptic for those other readers with the page numbers only. I can’t cut and paste from the paper FSM.

 

There is an 09 HHR 2lt Floating around with even another fuse connected to the battery and wiring from the stock amp. Whoever bought my old HHR might be slightly confused if they stumble upon that. Sorry this post just made me think about that.

 

I stand corrected Sno White, the fuse being for the BCM does make sense.

 

Thanks guys. I see it all now. 3 volumes of shop manuals is a lot of information to sort through. Volume 1, 2 and 3 .......geesh!