So recently I replaced all my bulbs with LED's. I started with the license plate bulbs because they were burned out. Then I got to the turn signals, brakes and back-up lights. This caused Hyper flashing and I replaced the relay under the dash by the brake pedal with one that stops the hyper flashing. Then the 3rd brake light went out so I replaced it.

I went for a drive after all this was said and done, only to find my cruise control does not work anymore. I have a feeling it was the relay near the brake pedal, so I attempted to swap it back to the old one and deal with the hyper flashing but upon doing so, I hit the turn signal and was met with a low pitch hum that was constant instead of the flashing and tick noise. The dash light indicators for turn signals also remained constant. So I put the new relay for the LED's back in.

Originally, the reason I knew the 3rd brake light was out was troubleshooting through googleabout the cruise control. So I hoped that would fix it. Well, it didn't.

I have read a couple other options to check, but wanted to see if anyone here had suggestions on where to start. Specifically fuses and their locations.My guess is there might be another relay or fuse causing the issue.

I had no idea swapping to LED's would cause so many issues but it does make sense because of the lower power draw. Since my truck does not have a fuse box manual, I will check google for that too unless someone can show me here. The problem was today was my only day off and I spent all day at autozone swapping bulbs and fixing this until it was dark and I just don't have the time until tuesday and wednesday, and it gets dark here in MT around 5:30... along with freezing wet weather. So any help to speed this up would be much appreciated.

 

You need to provide the specific year of your truck. There were several years' models that, if you replaced the 3rd brake light with LEDs (or if it burned out) the speed control was disabled.

 

Sorry.

06 4wd 5.4 4 door

Pic in my profile.

 

Put conventional incandescent bulbs in the 3rd brake light.

 

Gonna try that first today after work. I really don't want to return bulbs and the housing for the 3rd brake light was pretty melted, so I am hoping that putting conv. bulbs back in will be okay. Sounds like a good reason. Just curious though, is there a separate relay for the 3rd brake light I can replace to keep the LED?

 

Well, it worked.... but I am not satisfied. The replaced conventional bulb burned out and got so hot it made a bubble in the glass of the bulb and melted the plastic housing. I ordered a new housing and used "bulb grease" for the new conventional bulb, but I would much rather have all LED's. I have already replaced indoor bulbs with all LED's because there was melting on the housings as well. I'd rather be safe than sorry and have longer lasting, less heat emitting bulbs.

 

Take your pick: LEDS or cruise control.

LEDs lack a crucial characteristic that allows the brake pedal switch's position to be properly detected by the PCM thus disabling the cruise control.

 

Such a stupid design. At least with the turn signals and brakes there is a relay that is easily replaced.

Well, hope it doesn't burn out again. And at least I am able to have some LEDs to prevent this melting on those bulbs.

GJ Ford... New engine, tranny, full exhaust, IWE, and too many other parts to list and now I can't use LEDs on a 3rd brake light that's melted to prevent it from happening again... Pretty much sums up my experience with Ford and why I'll never buy another one. Not even a 5.0

I definitely see a brand new Tacoma in my future.

 

As they say, don't let the door hit you on the way out...

 

I love working on my truck, but hate spending the money to fix bad engineering. Thanks for the help.