I have a 2007 hhr with a strange turn signal problem. The left signal will sometimes work and sometimes not. I have changed out the front bulb which is the one that sometimes does and sometimes does not work. I changed it out thinking it was a bulb burned out then realized there were front and back specific bulbs so I changed to a front specific bulb in the front and tried again with the same results. I did notice that it will always work when the park lights are turned on on the switch handle. I have also replaced the switch handle with no change in the problem, still works sometimes and sometimes not, when in normal (Auto) headlight mode. I haven't yet tried to change any of the wiring or pigtails or any fuses or BCM since I am not sure which way to go next. The right side signal works fine. When it is not working it blinks fast.

 

Check the bulb holder for signs of heat and melting

 

I have checked the socket and it looks clean and not burnt so I believe I am looking at the BCM since the bulb lights up and flashes fine when I have the headlights turned off or when I have the park lights turned on.

 

How does that indicate "BCM"? That makes me think the wires are crossed in the connector. The 2 element have a common ground but completely separated circuits. The turn and parking lights are not even on the same connector to the stalk. The BCM supplies 12V to the turn signal/hazard bulbs. The parking light relay supplies 12V to the parking lights.
If you really want to, go out and buy a BCM have it programmed and say goodbye to your money.
The reason for different bulbs in the front is that 2006 and some 2007 model used the parking lights for DRL and the hotter bulb melts the lens. Front turn/park bulbs should be 3157, not replaces or comparable with. Most books think 3057 = 3157; many stores only stock 3057.


Has anyone done any "customizing"? Are all of the wires the exact same as they were from the factory, no splices no cuts?
Have you actually looked at both the front and rear when they are supposed to be flashing?
Is it flashing fast or not flashing?
Any LEDs?
Anything new when this started?
Do the marker lights work?
Do the DRLs work?
Do you have fog lights? Are they factory?
Is the CheckEngineLight on? Are there any codes?
Do all flash when using the hazards?
Do the indicators on the dash light up?

 

We need a wiring diagram of the system.

 

I don't feel like posting it again this week. What more do you need than the description I posted in #4?

 

Loose ground connection, burnt or loose bulb holder

 

Common ground; the turn, parking, marker and headlight . Separate sources.
I suspect the reason is a short inside the connector.
Or, we are not getting the big picture. I am reminded of "the chip I took out of the key fell on the floor" episode. We should know because everybody does the silly stuff they see on Facebook?

 

It could be the rear bulb causing the fast flash or no flash.

 

No customization. Nothing changed before this happened.
REar flashes correctly front does not.
Marker lights working. Emergency flashers work just not the front left. DRL's work.
Check engine light is on due to emissions error.
Inside indicators light up.
No led:s.
Strange thing is that I can get the front left to light up and blink correctly when I turn off the DRL's. I have also discovered that the front and rear bulbs have a different number so I have made sure to get the correct one in the spot they are supposed to be in. Then some times it will randomly work fine for the day without turning off the DRL's.