Brake Lights Off + Cruise Control Doesn't Do Anything

1997 Taurus GL, generally very good condition, about 90k miles.
If someone has any comments here, I'd really, really appreciate it!
Symptoms: Brake lights off AND cruise control stopped working. The
little green "cruise" indicator on the dash comes on fine, but when you try to set it to a speed, nothing happens when you release the gas (i.e. car just slows down just as it would without cruise).
I THOUGHT IT WOULD BE THE BRAKE LIGHT SWITCH BUT IT ISN'T!!!
What I've looked at:
- "Stop lamps" fuse: Checked it with light tester. FINE. - Brake light switch: tested that one end has power - FINE! And other end only has power when brake is pushed. FINE, switch working perfectly, transmitting electricity when brake is pushed!
So that puts the problem somewhere "downstream" from the switch, or potentially a wire right in the switch or nearby, didn't test those as didn't want to do any invasive testing and the wires themselves *looked* fine.
I'm thinking maybe there's another easy to replace switch somewhere that's less obvious than the Brake Light switch.
Any ideas?
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Well, the next logical step is to test at the brake light. Make sure to check both the +12V and the ground connection. Not familiar with the Taurus CC servo, but for good measure I would disconnect it and see if the brake lights work (be careful and not break the tangs on the CC servo connector).

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snipped-for-privacy@nospam.com says...

If the cruise light is on, then the system is active. There is an actuator that is connected to the throttle at the throttle body. Either the actuator is bad, the cable is broken, or the cable has come off the throttle body.
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wrote:

I believe it also has to have functional brake lamps for the cruise to work. Do the brake lamps flash with the hazzard switch? If not, all your brake lamp bulbs may be burned out.
Lugnut
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Hi folks, thanks for the comments. I hope noone flames me for what the problem turned out to be but as this person mentioned, it was in fact the bulbs preventing the cruise from working!
So, longer story, checked into it some more, did more testing as one other person suggested at the back bulbs, found that everything was working perfectly!! All the way to the back, signal was coming in upon pressing the brake pedal. Brake switch then was totally fine. But bulbs were not, testing of course proved that as well since they were still not doing anything even when power coming in.
So the cruise on the 1997 Taurus (at least on mine, assuming others) is apparently hooked up to the THIRD, i.e. TOP MOUNT brake light, and if the bulbs there are not working, cruise apparently doesn't do anything other than let you turn it on.
SYMPTOMS AGAIN AS I INDICATED WERE cruise light comes on but *does nothing.* I.e. you press the "set" button. NOTHING happens. Resume, etc, no cruise action works (except perhaps "coast" since that what was happening anyway once you took your foot off the gas!).
So, that high-mount light did have a bulb problem, but I never knew such a thing could be related to the cruise, I thought if the cruise problem were related to the brakes, it would have to be in a switch that was somewhere near the cruise control system. Never thought the cruise would have a connection to the rear end of the car to see if bulbs were working!!! So, that was the surprising thing, putting in the TOP MOUNT bulbs fixed the cruise immediately, which by the point when I was replacing them I was pretty sure was going to happen since in the whole system that was the only part that didn't test perfect.
So, that's the story, it's now a done deal, everything working.
FWIW, I'll add one thing for more info, ALL MY brake lights were not working (and this must have just started at the same point I noticed the cruise going out since I use the cruise on *every* trip), and I'm assuming that what was happening was that the two tail lights (which worked, but not for braking) were malfunctioning maybe for a long time and then the top mount was the last to go and because it always worked I never noticed the tail light brake lights not illuminating. That's my theory (because can't imagine they all failed at once). Then when the top mount went out two things happened: cruise stopped working, this was the first thing I noticed and then one person told us our brake lights weren't working, maybe one week later (! - amazing how reticent people are nowadays to help with simple things like that!).
Anyway, point being, I know it was the top mount bulb because I had to replace all of them and that was the first one I did because it was so easy. It was another day before I did the back tail lights and in the mean time the cruise was perfect, again, immediately after restoring the high-mount brake light but *before* fixing the other lights.
So, the top-mount brake light bad bulb was the reason for the failure.
Now, I could tell some more stories about why it took an extra day just to put in the tail light bulbs. Quite a chore Ford made that! But now that I know what's involved, not all that bad, and memo to Ford: IF that kind of greater difficulty setup makes it easier to make the trunk very usable, I'm all for it as the trunk being usable much more important than a little difficulty every few years replacing bulbs.
I don't think Ford is listening though since the bastards have discontinued the Taurus. Unbelievable SOBs!!!
So, anyway, that's the story, hope someone enjoys and learns...
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wrote:

Glad it worked. Too many people do not regularly check their lights. Checking brake lights is not that difficult when you are driving. You just need to familiarize yourself with their illumination pattern. Since you are in the car anyways, it shopuldn't take any extra time. You can see the reflection in the mirrors from following cars or other objects behind. Even driving down a dark road and applying the brakes occasionally to see the illumination on the roadway will tell if you have anything at all. Other drivers can also be helpful unless you have someone like the lady(?) I pulled alongside a few days ago at a light to tell her the LR tire was near flat - she gave me the finger and graphic instruction on what I could do with that info for acknowledgement.
Lugnut
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I have seen strange electrical designs, but providing ground to the CC circuit through the brake light bulbs beats them all! Unless someone pulls a manual and actually proves that this is how the system was designed, I would suspect that the OP has a defective/disconnected ground connection to the CC, and it gets it through the brake bulbs instead.

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On Fri, 17 Nov 2006 22:35:51 -0800, "Happy Traveler"

If you install failed brake lamps in all the positions of most Fords over the last few years, the cruise will not work. I have never bothered to look to see why. I more or less assumed this is the way it was intended. I won't pretend to understand the logic other than to make sure the driver has just one more reason to be sure one or more of his brake lights work. Many drivers never bother with safety items unless a convenience item gives them a problem first. This is in the same category of some older Toyotas I had where the instrument lighting not only went out if the tail lights did not work but, the alternator would not work. This would eventually get you off the road one way or another. Maybe some sinnister engineers along the line?
Lugnut
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happy snipped-for-privacy@abc.net says...

I scanned the relavent information from my 2000 wiring manual and put it here if anyone wants to decode it: http://home.att.net/~andyross/TaurusCruise.pdf
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Happy Traveler wrote:

It's a fail-safe. Some (a lot) drivers just tap the brake pedal to disengage the cruise, this was actually a simplification move, a lot less wiring & switches. Also, it prevented two-foot drivers from driving down the road in cruise while riding the brake.
The vacuum dump valve was another fail-safe built into Ford systems, in case the electrical system failed to kick the cruise off.
Rob
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