Brake Lights - Chevy Cobalt Forum / Cobalt Reviews / Cobalt SS / Cobalt Parts
Register Home Forums Photo Gallery Garage Search Today's Posts Mark Forums Read Auto Escrow
Problems and Service Talk about any mechanical problems you are having

YourCobalt.com is the premier Chevrolet Cobalt Forum on the internet. Registered Users do not see the above ads.
Closed Thread
 
LinkBack Thread Tools Display Modes
  #1  
Old 06-12-2012, 09:42 PM
Red27's Avatar
Newcomer
 
Join Date: Apr 2011
Posts: 14
Red face Brake Lights

Ok so here's the problem while driving the car the lights turn on all around, but when braking only the third brake light turns on. all the signals work so I know the bulbs are good.

Does anybody have a clue as to why this is happening or possibly an innovative solution that I haven't thought of yet?

Oh and just in case it's important the car is an auto 07 LT

seriously though I'm stumped here
Sponsored Links
Advertisement
 
  #2  
Old 06-13-2012, 01:45 AM
Veteran
 
Join Date: Jan 2012
Posts: 584
Garage
Okay, so what have you checked already?

Fuses or anything?

BTW, do they turn off when you hit the brake?
Or do they just not get brighter?

[Insert signature here]
  #3  
Old 06-13-2012, 04:24 AM
Coby7's Avatar
Super Moderator
YourCobalt.com Premium Member


 
Join Date: Oct 2011
Location: Magnetic Hill, New-Brunswick
Posts: 8,859
Garage
To start off, there is only one brake switch, this switch supplies a ground to both (high brake light and brake bulbs on either side of your Cobalt) this same switch with the same contact also disactivates cruise if it's on. So you know it's not your brake switch.

2. High brake light has battery B+ which differs from tail brake light which has ignition 1 B+.

3. Brake lamp fuse refers to tail brake lights and not high brake lights.

For rear tail brake lights to work ignition has to be on, (with a good fuse) while high brake lights come on as soon as you touch the brake pedal.

My theory here is, You assumed your brake fuse was good because you have high brake lights working. I would check brake fuse #9 (10 amp) on BCM fuse block in passenger side center console . This is your most likely cause.


High brake light fuse is same as trunk courtesy lamp and rear window defog I believe.
__________________
Every minute spent angry is a happy minute lost for ever and ever!!!
Drives 2007 Cashmere metalic Cobalt LS Sedan 2.2L auto 1G1AJ55F977161789
Drives 2010 Crystal Claret Metalic Cobalt LT Sedan 2.2L auto 1G1AD5F57A7173167

Never drive faster than your guardian angel can fly

Last edited by Coby7; 06-13-2012 at 04:32 AM.
  #4  
Old 06-13-2012, 12:57 PM
ChevyCustSvc's Avatar
Chevy Customer Service
YourCobalt.com Premium MemberExpert
 
Join Date: Nov 2010
Posts: 757
I hope you've had some luck checking into the fuses; if you were to decide upon bring your Cobalt to your dealership, or would like for me to check for any open recalls/provide warranty information, please send me a private message that includes the last 8 of your VIN and we'll go from there.

Best,
Sarah
GM Customer Service
  #5  
Old 06-13-2012, 04:30 PM
Red27's Avatar
Newcomer
 
Join Date: Apr 2011
Posts: 14
Ok so I checked the fuses and they are good. And fuse 9 in the passenger side controls the high mount stop light. What I did was test the wires going to the brake lights to see if there was any current going to then when the brakes are applied but no dice. Although from what I'm reading I think I should have been looking for ground instead. Is that right?
  #6  
Old 06-13-2012, 06:07 PM
Coby7's Avatar
Super Moderator
YourCobalt.com Premium Member


 
Join Date: Oct 2011
Location: Magnetic Hill, New-Brunswick
Posts: 8,859
Garage
I will try and download the brake schematic...

---------- Post added at 09:43 PM ---------- Previous post was at 09:25 PM ----------

But until I find it heres what I found on 2007 stop lamp.Stop Lamps....
The body control module (BCM) is responsible for controlling the stop lamps. When the driver presses the brake pedal, the BCM will receive a signal from the brake pedal position sensor. The BCM then supplies battery positive voltage to both left and right stop lamp assemblies and to the center high mounted stop lamp (CHMSL). The stop lamps are grounded at G401 and G403. The CHMSL is grounded at G302.

---------- Post added at 09:47 PM ---------- Previous post was at 09:43 PM ----------

Do your 4way flashers work in the back?

---------- Post added at 09:47 PM ---------- Previous post was at 09:47 PM ----------

Do you have OEM bulbs?[COLOR="Silver"]

---------- Post added at 10:07 PM ---------- Previous post was at 09:47 PM ----------


OK, this might also be my mistake, there is only one brake switch but it has 2 wires on one of the terminals. If you hear the shifter solenoid when you press the brake pedal this means BCM is getting the brake pedal signal therefore no broken wires at switch . So problem has to be BCM if you have 4way flashers. Anyway here's the diagram. If you need any help understanding the diagram feel free to ask.
__________________
Every minute spent angry is a happy minute lost for ever and ever!!!
Drives 2007 Cashmere metalic Cobalt LS Sedan 2.2L auto 1G1AJ55F977161789
Drives 2010 Crystal Claret Metalic Cobalt LT Sedan 2.2L auto 1G1AD5F57A7173167

Never drive faster than your guardian angel can fly

Last edited by Coby7; 06-13-2012 at 06:35 PM.
  #7  
Old 06-13-2012, 07:40 PM
Red27's Avatar
Newcomer
 
Join Date: Apr 2011
Posts: 14
The 4 ways flash, but when braking the lights don't brighten up. As for the schematic I can follow the basics of out I'm just unsure of what it's telling me. But now I see that I need to look for the bcm and see what I can find wrong there
  #8  
Old 06-13-2012, 07:52 PM
Coby7's Avatar
Super Moderator
YourCobalt.com Premium Member


 
Join Date: Oct 2011
Location: Magnetic Hill, New-Brunswick
Posts: 8,859
Garage
It is the same wiring for Brake lights as for 4 way flashers. So your wiring is good. Looks like you might need a visit @ a garage with a Tech 2 because I think your BCM has shit the bed. But to make sure you can check pins "A9 and A12" of C3 of the BCM to see if you have voltage when applying brake with ignition on.

---------- Post added at 11:52 PM ---------- Previous post was at 11:51 PM ----------

Are your 4way flashers bright?
__________________
Every minute spent angry is a happy minute lost for ever and ever!!!
Drives 2007 Cashmere metalic Cobalt LS Sedan 2.2L auto 1G1AJ55F977161789
Drives 2010 Crystal Claret Metalic Cobalt LT Sedan 2.2L auto 1G1AD5F57A7173167

Never drive faster than your guardian angel can fly
  #9  
Old 06-13-2012, 08:22 PM
Red27's Avatar
Newcomer
 
Join Date: Apr 2011
Posts: 14
The flashers seem to be normal to me. with the parking lights on and the 4 ways on you see both filaments burning. Not really sure if theres more to it than that. while I get the basics of the schematic, I don't see where the bcm is located. Could you possibly point me towards it's location?
  #10  
Old 06-13-2012, 08:30 PM
Coby7's Avatar
Super Moderator
YourCobalt.com Premium Member


 
Join Date: Oct 2011
Location: Magnetic Hill, New-Brunswick
Posts: 8,859
Garage
You mean on the diagram or in the car?
__________________
Every minute spent angry is a happy minute lost for ever and ever!!!
Drives 2007 Cashmere metalic Cobalt LS Sedan 2.2L auto 1G1AJ55F977161789
Drives 2010 Crystal Claret Metalic Cobalt LT Sedan 2.2L auto 1G1AD5F57A7173167

Never drive faster than your guardian angel can fly
Sponsored Links
Advertisement
 
Closed Thread


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -7. The time now is 01:16 PM.


Powered by vBulletin® Copyright ©2000 - 2014, vBulletin Solutions, Inc.

Garage Plus vBulletin Plugins by Drive Thru Online, Inc.

Content Relevant URLs by vBSEO 3.3.2