I had this happen yesterday. For me it turned out to be the two main battery cables (one from rear of vehicle and the one to the starter) where they meet/join together at the fuse panel. They were clean of corrosion and looked fine like grey steel/tin ring connectors, but are in fact copper DOH! I took them off and wire brushed them back to nice clean copper and reinstalled. Fired up like new. Took 5 minutes to fix.... once I got to thinking about amp draw and corrosion.

Hope it helps.

 

Welcome. Glad you were able to find the problem on your's. That connection at the fuse box is a known trouble spot for corrosion or even a loose cable end. It's always one of those places we recommend checking when folks have voltage issues.

The OP of this thread hasn't bothered to come back. So, he won't get the help of your 1st hand experience/fix.

 

Good tip! The HHR has a more complicated grounding system because if the rear mounted battery. Ive added ground straps on mine.

 

Not so much "More complicated" as to more susceptible to poor maintenance. Semi trucks have the batteries mounted further away and work fine with a cable going to the frame for ground and then all circuits going to frame for ground. Positive side usually has one wire going to starter and another going to the alternator with all the circuits going to them for power, Trick is to make sure the connections are all good or weird ass feedback/poor ground issues arise. Putting more ground straps on is an excellent idea but still need to be maintained since all the extra straps are doing is creating a "Backup connection/fail safe" for ground.

In the HHR's case the entire body becomes a ground and the Main Fuse Box the Power Distribution Center.

 

"That connection at the fuse box is a known trouble spot for corrosion or even a loose cable end. It's always one of those places we recommend checking when folks have voltage issues." Yet no one had in this thread.

"The OP of this thread hasn't bothered to come back. So, he won't get the help of your 1st hand experience/fix." Perhaps the next person searching for "HHR Won't Start" will.

 

See post #7, donbrew suggested checking that.

 

I stand corrected!

 

Worked on a lot of trucks employed by my Cat dealer. And yes terminals are an issue at the batteries (4 batteries). But it starts to get worse when a truck manufacturer throws relays into the battery box also.

 

LOL... yes, yes it does. 32 years general diesel mechanic.

 

Those are "tinned" connectors, supposed to be that color with solid copper underneath.
Marine wire is generally tinned, an added edge against corrosion.
Pretty much all the quality crimp connetors you buy are also solid copper, tinned.

The best way to clean the corrosion off of cable ends is to use a hot water and baking soda solution in a cup and let the cable end soak in it. When the bubbling has stopped, it is as clean as you can ever get it.
You can also brush or wipe the solution on the battery terminals.

I have always used copper antiseize on the battery connections and frame connections and have never ever had to go back and clean them. Works much better than any store bought protectors.

GM, in their mighty wisdom, back in 69 to 82 with their C3 Corvettes, ran a long cable from the battery mounted behind the driver's seat to the starter.
Many owners had trouble with this.
Although the cable looked like 00 gauge copper, it was actually copper clad aluminum wire that would corrode from the inside at the crimped connections.
I didn't even know that cladding aluminum with copper was possible. The fix of course is to replace with real copper wire, I always used 900 strand welding wire.