3rd brake light has no power at the bulbs ... brake light switch? ---
 

My third brake light isnt working ... its not getting power to the bulbs.


I was told to check the brake light switch under the pedal. I have never swapped one of these before ... is one 3 prong connection to the tails and the other 3 prong connection to the 3rd brake light?

Is this the one I would want to replace it with? :

http://cgi.ebay.com/ws/eBayISAPI.dll...ink%3Atop%3Aen

If this isnt the fix ... where should I check next? I couldnt tell if the wiring goes down the driver or passenger side of the vehicle from the 3rd brake light. Which side would I need to start searching on? Could it be a fuse?

Thanks! ---

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

According to the 1990 FSM it gets its voltage thru the brake switch on a light blue wire.

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

Do your rear brake lights work?

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

My rears work, but my 3rd brake light isn't working and I need it to work to pass state inspection.

I tested the voltage at the bulbs (took the 3rd brake light assembly off and tested close to the bulbs while pushing on the brake pedal).

Is that the right switch I need if I just want to replace the assembly under the pedal?

Thanks! ---

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

Buy this local or if you insist do eBay for it:

http://www.ebay.com/itm/ACDelco-D852...f82189&vxp=mtr

You could also take that GM number to your local NAPA, CARQUEST or whichever parts store is close.

You can check the lt blue also at the ABS module when depressing the brake pedal. There's a splice and both are supplied from the splice. If you've got power at the ABS lt blue then it's NOT the switch.

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

Awesome info WVZR-1 ... thanks for saving me from potentially buying the wrong switch! I appreciate the testing tip too :) ---

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

That BWD is likely correct but I didn't see the direct change from GM/ACD to the BWD in the interchange I use most frequently. It does appear to be pinned correctly so I believe it will work if you wanted. I just believe for less expensive competitive stuff "why not local"! The guy will remember/recognize you the next time when it's maybe something more expensive. Any chance for a conversation with a quality parts guy will generally work to your advantage.

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

You may also want to pull,the halo trim and look at the intermediate harness connector. It will at least show you how far power is getting.

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

There is no easier check than in the LH rear compartment at I believe C400 to the ABS. No hush panel to remove first, no halo to remove. The splice is before the C400 so if there's power at the ABS the switch is working, no hush panel to remove. If there's no power there it's time to do the LH hush panel and I believe it's much easier to go there than remove the halo. If the SLS is actually working and no power at the ABS and we already know no CHMSL then it's time to go deeper.

The switch is the likely culprit and I believe I'd rather do the hush panel and switch before removing trim on the halo.

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

LH = drivers side, right?

I'll find time in the next couple days to do some searching and testing as long as the rain stops, and I will update with what I find out :) ---

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

Everything I do I do sitting behind the steering wheel

LH = DRIVER

except when doing a transverse engine and then I stand behind the flywheel looking towards the water pump (EX: exhaust manifold closest to front bumper is NOT front but LH)

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

14043256 is the cruise release switch - not what the OP needs. There will be no "plug and pray". This will likely be the needed fix and the diagnostics should eliminate "the pray"!

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

I just went through the exact same problem, for the same reason.......two switches, one for the cruise and one for both sets of brake lights. Mine was the switch, $8.00 at Advanced Auto.

http://i337.photobucket.com/albums/n...ps6nms1qq1.jpg

Hope this helps.

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

I took off the old brake switch, and it showed continuity ... but replaced it anyway with an ACDelco piece.

My 3rd brake light is now working again to my surprise!

Thank you all for your help :) ---

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

Glad to hear!!

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

Good to see this resolved!

I had the "reverse" situation - my third brake light would light, but the 4 brake lights (though left/right, and driving lights (lower power 'ON' all worked).

Problem turned not to be the brake switch, but a small 37uF capacitor across the connection (blue and orange wires, I think I remember it as, but don't rely on that from my memory!). I replaced the capacitor and they all worked again. Either a lose or shorted connection.

This was on a 92, I seem to remember at the time that this was put on in 92 (so may not be there on the 90) to cope with arcing potentially messing up the ABS and ASR...

Anyway, just my 2c, but if a new brake switch fixed it - good and glad to hear it :)

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

This thread just gave me the information to fix my third brake light problem. Switch! Thanks!!

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

Thanks!! Great info. Used the part number you gave too

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

The brake light switch change out is a memorable experience of muscle cramping!

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

Replaced my switch last winter, unless you are gumby I recommend taking the drivers seat out and top off....Oh yea make sure you have a assistant to pull you out when you are done.

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

Haha. That's for sure. You have to be a contortionist!

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

I didn't have to take my seat out, but then again I'm 140 pounds soaking wet and kinda flexible....But it was good no little kids where around, because the cuss words were flying. Also I pushed my switch in to far, and my brake lights would stay on. Have patience and do some stretches lol....

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

Yep, do some stretches...I'm getting ready for a road trip in a few weeks and my son told me my 3rd brake light was out. Went to parts store picked up part and sure enough it was the switch.


If you don't take the seat out I will contest you have to be a contortionist. I had a easier time replacing the master clutch cylinder and I swore if I ever had to pull the hush panel and get under there again I would pull the seat..Yep, I forgot............


Steve

Re: 3rd brake light has no power at the bulbs ... brake light switch? ---
 

Ive ventured under there 3 times. Twice to replace the clutch master cylinder and once for the brake light switch. Im 6'2" 265 no amount of stretching will help, the seat always comes out. Im pretty good at it now.