I have a 99 mountaineer with the v8 and my cruise control stopped working does anyone know what could be wrong?

 

1. Blown fuse
2. Bad Clock Spring
3. Bad switch
4. Bad deactivation switch
5. Bad Servo
6. Bad cable or disconnected
7. Bad Horn relay
8. Bad brake light switch

Is that enough for starters?

 

I would try the horn first. If it does not blow, then you know what it is. Ford has had a problem for years with the horn grounding itself out. Both the horn and the cruise are tied together...

 

fuse ok
clock spring ok
cable ok
horn ok
brake light switch ok

well i narrowed it down. but i don't know how to check the switch or the servo?

 

First test the deactivation switch under the hood. With a test light check to see that it has 12v on both pins while attached to the switch with Key on. The switch is mounted on the master cylinder and is red/orange in color. Then press on the brake pedal with the engine running several times and see if the light goes out when the pedal is pressed. You will need to be connected to the ground side when doing this. You can determine the hot side by unplugging it from the switch and seeing which one is hot all the time with the key on. While you have it unplugged check to see if the switch is full of brake fluid. If it is replace it, and inspect the plug on the servo to see if it is also full of brake fluid. You will need to clean out all the brake fluid in the servo connectors and the deactivation switch connector before proceeeding.

Let us know how this checks out and we will proceed with switch tests from there.

 

I checked the switch as you said and everything checks out.
what do I do next? thanks

 

Next you can check the pinouts on the servo itself. On the servo connector with the key on, You should have power at pin 7 GY/YE. If not then check fuse 10, a 7.5Amp fuse at the interior fuse panel. Then verify Pin 9 is hot, this is the same circuit coming from the breake pressure/deactivation switch you just checked. If no power there you have an open circuit in the wire from the deactivation switch to the servo. Then check pin 4 on the servo connector. This time you should have no power when the brake is not applied and power when it is applied. If no power when brake applied you have an open in the brake light circuit to the servo or fuse 9 is blown in the interior fuse panel. Check Pin 10 on the servo connector for ground. You can do this by connecting the test light to the positive terminal on the battery and see if pin 10 black wire lights up the test light. Pin 3 is the speed sensor input.. check for continuity to ground of about 220 ohms.. Ill have to double check that, but this usually isnt the problem. Pin 1 is the lamp to the instrument cluster that says speed control when engaged..dont worry about that one. Lastly we get to testing the speed control switches on the steering wheel. Using a multimeter set to ohms attach to pins 5 with the positive lead and 6 with the negative lead to servo connector. Check for 2200 ohms when you push the resume button, 630 ohms when you push the set/accel button, and 120 ohms when you press the coast button. Off should zero out. Then take the lead off of the pin 6 and ground to the battery, and press on button and you should see 12V. If all those conditions are met let us know.

 

http://www.members.shaw.ca/k2pilot/C...iagnostics.doc

 

Nice writeup but thats for the old vacuum servo type. His is an electronic servo.

 

Wow thanks for all this I will try this tomorrow. I would try it tonight but I misplaced my multimeter dammit!