"transmission thing" transmission issue and the door lock issue started at the same time and somehow are linked together. Most days the transmission does not do this, and it shifts properly. When the transmission is shifting properly the door locks also work properly and lock when you put in drive and unlock when you put in park. and dont randomly lock us out of the car. Every time we have taken it to drop it off to be looked at or fixed everything is always working properly. Then a couple days after we pick it up, it starts again. late summer it was doing it so bad that we just quit driving the HHR and drove our Pacifica for a while. pacifica was hit sitting on the side of the road at a friends house. Started driving the HHR again, and have driven it for the last 4 months with absolutely no issues till recently............right after buying and installing a brand new battery. drove for two days after replacing battery with no issues, and now this is going on. im trying to figure out if anyone else is having any of same issues, or ever has???????? this is what this place is for right???? or am i mistaken?????????? or maybe i was just smoking again while i left myself unattended today. Look guys im just looking for help, because its driving me nuts. i thought i came to the right place???????????/

 

Some of what you describe sounds like a bad connection/voltage issue. Check the main positive cable connection at the under hood fuse box. Also check the box itself for tightness and that all relays and fuses are fully seated.
Now the "shifts OK with the cruise on", that's the 1st time I've ever heard of that one.
Any chance that there's a Check Engine Light on that you didn't mention ?

A little advice on how to not get locked out. 1st. Never leave the car unattended and running with the keys in it. Use the remote start if you must leave it running. That way you'll have the keys and fob with you.
If you do leave it running with the keys in it, at least take the remote with you so you can lock/unlock it.

 

In post #5 and #7 , I suggest a course of action, I haven’t seen a response that you did anything about those, so did you check loose ground or connections at the TCM? Did you have the battery load tested, even a brand new battery can fail, or the terminal clamps crack and loosen off.
the under hood fuse block is also a place to inspect, are all the fuses and relays seated correctly, are the connections clean?
you can do these inspections yourself, in your own driveway

 

I'm thinking it is the neutral safety switch that is connected to the shift linkage on the top of the trans. I am about 800 miles away that's all the help I can offer (twice).

You make it sound like you are getting no help.

 

So you have 2 separate issues.

The locking doors issue, as has been suggested: battery load test(free at the auto parts store), loose underhood fuse block, neutral safety switch.

The cruise control/shifting issue is puzzling. Probably an issue with the TCM. As suggested, start by checking cleaning connections.

 

I believe it is 1 problem, since the lock unlock when the gearshifts from/to park works. Sounds like the linkage is misaligned or the switch is bad.

 

I have a 2009 Chevy HHR that started having similar issues first started with my doors locking on me while in park and running. Then the gearshift lever would not come out of park then the transmission wants to run in intermediate and not drive and does not go into 3rd gear with out a long high rev and have to give it some gas to shift. And gear shift would not lock into drive . Have change battery just got a brand new one had alternator checked. Changed out shift assembly no change. Need to know whats going on. TCM or BCM ? Took it to a mechanic shop was put on the machine had a few stores codes no engine light on. Desperately need help

 

WELCOME

 

Anybody check the new battery?
My guess is still the neutral switch.
Do you mean there were a "few stored codes"? If so, they might tell us something.
Check fuse #23 and #7 on the BCM. Check the door jamb switches. Check the brake pedal position sensor. Check the connectors to the TCM and ECM for bent or displaced pins. Check the ground location on the top of the transmission and the wire from it to the fender/radiator support (don't remember which). Have the ignition switch recalls been done? Check the connections around the ignition switch. Check the fuse marked "PK3" on the BCM #8 and #10.
All fuses and relays tend to loosen up with time, make sure all of them are fully seated.

 

That was my first guess. Or a pinched wire shorting intermittently.

Maybe try changing the door lock behavior DIC setup menu and see if the behavior changes likewise. Won’t fix it but might kinda sorta validates this idea.