So after dealing with a "hissing" sound that started about three years ago, and gradually got worse, I finally had my mechanic replace the brake booster Tuesday. "Hiss" gone. But now the cruise control stopped working!

Any thoughts please?

Thanks in advance. This is the closest I could find anywhere on the internet, from FixYa:

"Re: 2003 expedition cruise control not working (from FixYa):

I just fixed my Cruise control problem (2003 Ford Expedition). It didn't work at all, no light in the dash either. What had happened was, I had changed the brake booster some months back and when the brake pedal is disconnected from the booster shaft, it allows the pedal to raise too high.

It will contact the cruise control disconnect switch to the left of the brake switch. To find the switch, look close and there is a "L" bracket welded on the brake pedal and the cruise switch contacts this bracket. Well this switch is a self-adjusting switch designed to be installed with the pedal at least an inch or so depressed.

When the pedal is released it will contact the switch and push the shaft into the switch to the determined setting and it will lock into that position. I was able to pull the shaft out enough to make contact again and it self adjusted like it's supposed to and now the system works great!

What made me go to this switch was by checking power at pin 6 (blk/yellow wire) at the cruise servo connection. This connection has 6 pins and the end pins (1 & 6) both have 12 volts. Mine had no power at pin six, which means the cruise deactivation switch is the problem.

Older Expeditions had this switch on the brake master cylinder (recall for fires, etc), but 2003 and up has it on the brake pedal itself. Once I figured out where the switch actually was, it was easy to figure out. If you have done any work around the brake pedal and disconnected it for any reason, you gotta check this out."

 

Problem solved!

This thread was the clue that unlocked the mystery:

https://www.ford-trucks.com/forums/1...e-control.html

But still it took me reading the thread 10 times and trying things five times. So, I am going to post two photos and some more comments.

I've owned my current 2003 Expedition for 12 years, almost since "mile one" and restoring the cruise control was the trickiest thing and I've done in several minor repairs. Not even my mechanic who replaced the brake booster knew about this little thing to keep cruise control working.







What happens when the brake booster is removed:

As the poster on the other thread above said, when the brake pedal is disconnected from the old brake booster, it allows the tiny little plunger in the disconnect switch to get pushed deeper because the brake comes forward further when it is disconnected from the brake booster, than it would otherwise.

So, if this little plunger pictured above is not touched, the cruise/speed control system thinks that there is pressure on the brake pedal, not allowing the cruise/speed control to be activated, nor will you see the green activation light on the upper right of your instrument panel.

To fix the issue, with the vehicle in park (I had the engine running but I don't think it needs to be running) push the brake pedal at least an inch or two, exposing the plunger on the back side. This little plunger is the source of all the troubles. It "feels" like it is a simple button - pushed to turn something "on(or off)" and vice versa when it is not being pushed. In reality, this tiny little "button" has "micro settings" if you will.

I used a bent-nosed pliers to grab the head of the circled plunger, while the brake is pressed, to push this tiny plunger for the speed (cruise) deactivation switch forward (toward the firewall/engine). I was a little worried that I was going to pull the plunger right out of the switch, but even with a fair amount of force - that did not happen.

The poster above in the other thread said he heard some "clicks." You may or may not. There is no real "click" indicating that the plunger has been "reset." What you may hear is your pliers scrapping and banging on to things.

What you will notice if done properly, is that the head (top) of the plunger will feel like it is sticking out a bit more afterwards, maybe a 1/8" to 1/4" more. That is all! Just that little bit more of the plunger being exposed makes the speed control system believe that someone is not putting very gently pressure on the brakes.

I test drove the vehicle about six miles and the speed control system worked flawlessly.

 

Good job researching figuring it out.