troubleshooting cruise control

[hotairgypsy]

My cruise control had been working fine until this past week. What I did was replace the injector orings and I noticed after that the CC stopped working. I looked under the hood to see if i disconnected anything or something unplugged and nothing was obvious. I did some research but everything I was reading was leading back to the fuse or something on the steering wheel. I did check the horn and the horn still honks. I do not know where to start or test to see where the problem is so i can fix it.

any guidance would be greatly appreciated. I am getting worn out from working on this truck and would be nice to finish it up so i can just enjoy driving it instead of doing work constantly on it.

[JSchuricht]

First thing is to check you speedometer and make sure it is reading smootly rather than jumping around. Second, get a good scanner and you can test the buttons to see if the PCM is reading them correctly.

[hotairgypsy]

i have the snapon mt2500....any idea if that will tell me if the buttons are functioning properly... and the speedo is reading smooth

[issyrog]

thanks to this forumn I had some clues. Problem I,ve had with my cruise control is it will quit working and then come back on, time off varied. Theres a switch by the brake pedal arm I simply moved it around gently, presto cruise is working.

[issyrog]

Check issyrogs post

[1fastblackz]

sometimes you can "self test" the cruise control buttons by pressing and holding the "off" button while turning the key on.
-the cruise control light should flash a number of times
-then press "on", "resume", "coast", and "set" while watching for the cruise control light to flash after each button press.
-if all the buttons pass the test it will normally self test the control actuator by opening the throttle body(when equipped)
-if anything fails the test it will flash a single digit code that can then be further diaged.

[hotairgypsy]

i should have my truck back tomorrow. had the tranny replaced over the weekend and they are finishing things up on it in the morning...then back to testing...will keep you all posted.

[TwoBearBill]

I have a 2001 F450 with 7.3l and auto trans. My cruise just quit one day. I have a cruise control circuit wiring diagram, so I'm slowly finding the wires and components that are involved.

I understand the rear differential speed sensor should be checked - how do I get to it?

Any photos of components would sure be helpful - or suggestions for a good shop manual other than Clymers.

thanks,

[1fastblackz]

the rear differential speed sensor is located right on top of the rear differential. It is fairly easy to get to and only involves removing a 8mm/10mm bolt to be able to remove the sensor. Looking at the sensor will normally not show any issues. Sometimes rodents like to chew the wire going to it though and that could be your issue. The best way to check it is with a scan tool that can show live data and watch the rear speed sensor while in motion to be sure it is reading correctly. did you try doing the self test that i mentioned above in post #6? If you do that and it spits out a code post it on here and i can tell you what it is.

[TwoBearBill]

We are full time RVers - I can see the sensor on top of the differential, but can't get under the truck to get to it because we're in an RV park and the truck is too close to the ground (or my stomach is too high off the ground) so I'll have to pull the truck up on some blocks tomorrow to get more clearance.

I did try the self test holding the OFF button down while turning on the key, and the cruise light on the dash DID NOT light up at all. I checked the wire that goes to the clock spring in the steering wheel and it IS hot, so that makes me think the steering wheel switches are probably OK.

I plan to keep this truck forever - it is 12 years old now and has only 68,000 miles on her. What model diagnostic device is the best and where do I get one?

thanks for the help - I plan to post photos AND the solution when I (we) find it.