Can this be true? comments please!

So, what is your question? Make certain your brake lights are in working order before troubleshooting. What part don't you understand?

If it is in print, than it must be true.

Tom

In print or not, it's true. And if both of them are burned out, the speed control won't work.

I understand Cruiser's question. I guess I would have the same one. I have worked on many cars over the years and have never come across any in which the lighting system has anything to do with how the vehicle might idle. I guess it does on this one but it's pretty wierd nevertheless. Also, no need to be caustic. Cruiser may have an answer you a question you pose one day. jor

This is nothing. There was a foreign car years ago where the cruise control would not disengage if a particular brake light bulb was burned out. Now that is bad engineering!

Not only won't the cruise control engage but you will notice other strange symptoms also. Your shift points may change, In high gear the TC may not lock up and the ABS indicator may come on. Been there and done that. 1996 F-250 4X4 PSD automatic. When I gave those symptoms plus "No turn signals and no brake lights" to the Service writer at the Ford dealership, I explained that all of the symptoms appeared instantly at one time. I also told him that I had already checked all of the fuses and found them all good. He told me that it sounded like the computer took a dump and suggested that I leave the vehicle with him. After all, what are the chances of both filaments breaking at the same time on a bumpy road during daylight hours with no lights on? I sure am lucky that I saw that large jar of Vaseline the service writer was hiding behind his back.

All the manufacturers have been cutting corners, trying to save money and weight on vehicles. As a result many of the circuits are shared. They can use shared grounds. Seems like it makes sense to piggyback with the lights because you can so easily verify their integrity if you follow the directions.

Oh, guess where the passive restraint module is on my '94 Saturn. Right under the cup holder on the console. Condensate from the cups runs right down through the console and onto the connector. Corrosion city there. Passive restraint module was replaced twice under warranty and is bad now. Guess what belt got cut.

" Cruiser" wrote : : Since the brake light bulbs are wired into the BOO* switch, check : for ANY burned out bulbs that might cause the engine to idle poorly : because of the open circuit (brake on signal). : Yes, it is true. The brake light circuit controls the smog section of the ign comp, reducing emissions when decelerating. Among other things you may notice that when you let off the gas and just touch the brake pedal enough to light the lights, the RPM will drop lower than when simple decelerating w/o touching the brakes. The circuit also disengages the auto trans lockup clutch and some other bits. It's all pretty busy.

Hope that helps. Dave