I have searched this site for days on this subject to no avial so i joined just to post this question. I have a 2007, manual transmission coupe. The light outage indicator comes on when I driving and use the brakes. It goes off when I release the brakes. When this happens there are no brake lights, none of the three. I have replaced the bulbs on both side brake lights, replaced the fuse. There is no brake light switch on this model, confirmed by the dealer. When I replace the fuse I have brakes lights however the fuse blows with in a very short time. The first time after driving it to do errands for about 3 hours. Now almost immediately. Suggestions?

 

You might want to find another dealer ( see below )
Most likely a short somewhere in the harness from the brake relay to one of the lights ....

 

I have spent way to much time on my back and head staring under the dash, in the Texas heat, not to be sure about this switch. My girl does not go to this dealer in Katy TX, enough on them, but I wanted to see the schematics and to order the switch. Neither of the 2 switches I saw are under this dash, and no switch is located any where near the brake peddle.

Can anyone ascertain what would indeed cause the fuses to continue to blow?

I searched that area of the site until I had a headache looking for some area that remotely resembled where I would find this to no avail. I know that I am being a bit pissy here, please forgive me but could you narrow it down as to where I would start?

 

I am now hot, sweaty and now thoroughly embarrassed.........my computer did not display your inset until l I sent my reply......

Pondering what you sent......THANK YOU!

 

You say the fuse now blows almost immediately, right ?
I would first remove the brake relay and drive around a parking lot or something ( NOT public streets/roads ) to see if the fuse still blows immediately.
If it does not, then I would then try replacing the relay to see if this resolves.
If that doesn't do it, then it has to be a wire going to the left/right/top stoplight from the ICM ( light switch ) being shorted out.

This is where it gets interesting.
The schematic shows that pins 5,6 and 7 of the light switch ( illumination control module ) supply voltage to the left, right and center brake lights.
You have to disconnect the plug from the module and use a meter to measure resistance to ground from these pins.
First, remove the bulbs and disconnect the high mounted lamp.
Using the multimeter's beep function, connect one lead to pin 5 and the other to a good ground. ( follow by also testing pin 6 & 7 )
open/close doors, trunk lids etc and wiggle whatever wires you can get your hands on.
If you hear a beep, that indicates a short to ground in that circuit.
You're kinda on you own from that point in locating the short, sorry.

BTW, you can download the entire service manual from the below link(s) in my signature.

 

Yes it blows almost immediately. I was going to test tonight to have a number to what immediate is. I can test by driving in my neighborhood and use the garage door to see the brake lights.

I am a girl but thanks to older brothers I have rebuilt carbs, changed brakes and water pumps however this brake relay, thing has me stumped. Are "relay and switch" being used interchangeably for the same part? From what Ii see in the first post I can not change out the brake switch, no? I just went out to stare at the piece shown. That switch looks like it can be disconnected though.

Thank you for your patience.

 

NO, relay and switch are different parts. The relay is the one at the back of the under hood accessory fuse box closest to the engine. The switch is on the brake booster assembly also in the engine bay.

 

make sure you have installed the correct bulbs

 

That is a good point, some of these two filament bulbs look correct but sit on the wrong socket pins.
I guess we have that kind of bulb I have never had to look.

 

Thank you all for the input. The reason for this long text is to document everything for the next person who has this problem, as I must agree with other comments that not enough post do this.

So far I have unclipped every connecter I could find on and between the brake booster and the tail lights with the exception of the high center light. (can someone share how to remove the trunk lid lining here as I can only find one screw here, no clip covers or other areas of entry. It is a solid plastic piece and I am hesitant to start prying and puling on it.) I worked them back on forth on the pins encase of corrosion. Pulled the bulbs and resat them. Once it became dark so I could see the brake lights, only myself working on this, I put a new fuse in and the brake lights worked once I depressed the bake peddle; the dash warning light went out. I depressed the peddle a number of times and no blown fuse. At this time I had company stop by, the end of my testing for the evening.

I will pull the bulbs again to make sure they are the correct ones. (OH, side note the blinkers really are just blubs with orange coating on them. Can I buy orange bubs, not orange coated bulbs as I should replace these since the coating is pealing?) then I will drive the car around and see how long the fuse last dependent on that outcome I will move on to the relay, thank you for clearing that up for me.

This will take a few days as for obvious I can only see the brake lights at night. I will post once I have more input to share.

 

1)Checked, checked and rechecked the brake light bulbs (not the high center light). They are working and they are they are the correct bulbs
2)I installed a new fuse, made sure the brake lights were working a went for a drive. The fuse lasted about 5 min. and 15 brakes.
3)Pulled the relay, drove about 2 hours and countless brakes over 5 days. No brake lights at this time. The fuse did not blow and the "light out sign" did not come on.
4)Installed a new brake relay, the fuse blew with in 2 min. of starting the car and touching the brake."light out sign" is back on.

Now to check the wiring.

Can you/will you send me a diagram on how to pull the trunk lid liner for a 2007 coupe?

 

You need to download : http://api.viglink.com/api/click?for...13732426688348

( The 'Illumination Control Module' ( ICM ) is the headlight switch with all those fuses attached )

 

What is that download? it is taking 10 mins +++ to get? I gave up. I have a high speed connection.

 

I got it in 1.5 minutes, but to my surprise it was the owners manual, not the repair manual.

this should be correct for the repair manual :

http://api.viglink.com/api/click?for...37326859556610

 

Never did check the the ICM ( light switch )

1) Checked the wiring visually as much as possible.
2) Changed fuse and found out the high- center brake light was not working when I touched the brakes although the 2 brakes lights were working.
3) Unplugged the high- center brake light, fuse is not blowing and the the "light out" dash warning light is not on any more.

Now to price out a new light. It is an led strip in the 2007 coupe.

 

call Logan Diagnostic at 615-479-1900 and ask them if they can fix it for you.
( Cadillac LED Replacement 3rd Brake Light, High Mounted Brake Lights, Third Brakelights For Escalade, Escalade EXT, ESV, Seville, SLS, STS, Catera, Chrysler Crossfire Roadster

 

Disconnect negative battery post for 30 seconds & reconnect.

This action will reset the computer & remove the light.

 

New update:

Sent center brake light off to be rebuilt....the light was working and did not need to be fixed. So now back to the beginning.

• I checked all the fuzes for the whole car. Fuse still blowing.
• Replaced the brake rely (again). Fuse stops blowing! Center brake light still not working.

Car will pass TX inspection without the center brake light.