[speedeeSS]

So today I found out none of my tail lights work in my 07 TBSS. Left, right, and 3rd are all out. But my blinker, parking lights, and reverse lights work fine.... So I started with the basics. Checked ALL the fuses under the hood and under the rear seat that pertained to the rear lights and 3rd brake light. All were good and not blown.

Next, I checked the bulbs. All bulbs the were good. I even swapped the good blinker bulbs in the 2nd slot with to the top, no luck.

Then I checked the switch on the brake pedal. Not too sure what exactly I was looking for so I measured the voltages at the brake light fuse slots on the fuse panels. Pulled the fuse, attached a DVM meter to the open pin slots, had someone hit the brakes, and had the tone go off showing the circuit was working. So it shows me the switch at the pedal is good.

To me it seems there may be a cut in a wire or something. If it was grounded out, I'd think I'd lose a fuse. Does anyone know how the wiring works from the fuse panel --> the rear lights? Is there a bridge somewhere for the 3 lights?

And just so everyone knows, Im not a newbie... I did a search and came up with this thread. This is the closest to my situation. http://forums.trailvoy.com/showthread.php?t=53234" Any help would be appreciated. Thanks all!

 

[RayVoy]

I'm not too sure about the switch test, sound like you did a continuity check, not too sure.

But, the circuit is pretty simple.
Battery from fuse # 12 (under hood), through the switch, to the rear fuse panel. There the path splits, fuse # 34 to left/right tails, fuse # 16 to centre light. Lights to ground.
There is also a lead from the switch (load side) to the flasher assembly (stop signal for trailer lights), and a lead from fuse # 34 (load side) for the trailer brake controller (if used), and the cruise control.
The only common, parts, are switch and 1st fuse. And wire of course.

 

[speedeeSS]

Thanks Ray. So after chillin out and re-attacking this issue, here's what I came up with.

- Had +14V at fuse 12 under the hood. So I knew that was good.
- Propped the brake pedal back and measured ground to fuse 34 and the 3rd brake light fuse. 0V at both those points.
- Only common denominator left was the brake pedal switch.

Took the switch out, all the pins looked fine. So I seperated the black and white halfs and found the 3 seperate contacts inside. 1 pin was so shifted, it was causing the contacts to not make a proper connection. I straighted it out, put it all back together, and threw it back into place. Brake lights are back in action!

I've attached a few pics for reference and archiving reasons for others who may need help one day. Enjoy!

 

[the roadie]

Appreciate the pics for the archives. You saved yourself at least $20. Much more if you had to pay a mechanic to swap it out.

 

[BTMinn]

Good trouble shooting description. Photos are really clear.
:thumbsup:

 

[speedeeSS]

I'm glad to help! Also for reference, the pin that was out of place was the 2nd one in from the right (copper). In the first pic, you can kind of tell its shifted a little bit. Im not too sure what the pin layout is on the switch, but I believe one of the normally closed connections is for shifting (cant shift w/o foot on brake) and the other may be for cruise control. Then the normally open is for the brake light. Just my guesses...

And you're right Roadie, Im glad I saved $20 on the part or more if I took it to the stealership. But I am my own mechanic for 95% of everything that goes wrong on my vehicles.

 

[RayVoy]

Nice job speedee, think the contact will stay in place?

At least, if it goes again, you can pick up a new switch before taking it apart. :thumbsup:

 

[jarjar]

reversing lights do not work

hi guys,

I'm fairly new at this forum, so I'm just getting familiar with the website. Anyways, I have a 2003 GMC envoy XL for about 4 years now. My problem is that my reversing lights stop working. After changing the light socket and checking the fuses they still do not work. any ideas as to what the problem might be?

thanks :tiphat

 

[RayVoy]

Ok jarjar, 2 things.
1st, fill out the vehicle info for your profile (you can access under User CP).

2nd, you should have started a new thread, your gonna get lost inside this thread.

Ok, your problem.

You have/had water inside the back-up light socket. The water has corroded the socket contacts.
They can be cleaned, be careful. Worse case, the sockets will need to be replaced.

 

[speedeeSS]

I forgot to update this thread with the latest. 2 weeks after posting this, the switch failed again and I was left w/o my brake lights. This time, I was unable to save it like I had previously. Brought it into the dealer (I'm still under the B2B warranty), described my troubleshooting, and gave them the keys...

2 hours later, I get the manager coming up to me saying "Yup, it was the switch." Gee thanks for wasting my time! But I understand they must have a procedure for diagnosing problems. They replaced the switch under warranty and no problems since.

I just wanted to make it clear that even though I corrected the problem the first time, it wasnt a permanent fix.

 

[TXBlazer]

Thanks for the update....I'll order one for in the toolbox