Cruise control broke today

[spencergt66]

So i left work today in a good mood got a nice raise and a promotion and then when I left I jumped on the old hardy toll road home and hit the cruise I sat back and turned the ipod on to some nice music and then when i cam down off an over pass the truck stared to accelerate to maintain the set speed then just stopped i thought maybe i hit the brake or something so i hit the resume button and nothing then i tried to turn it off and back on and reset and nothing. Figures something would happen seams like it never ends with this thing cant finish one thing on it with out something else giving up owell what can ya do so as soon as the thing cools down Ill go take a look at it hope its something dumb like a broken cable or the cable just feel off we shall see

 

[Ironman03R]

Mine does that sometimes, the cruise cable would fall off if the throttle cable was binding. A new throttle cable fixed it for me.

 

[spencergt66]

Well I put new switches in the truck the other day cause the old ones fell apart but were still working so i figured hay maybe the switches are bad but no the have all the same readings so thats all good no bound cables or blown fuses so that leads me to believe that theres a broke wire or a bad controller some where don't have a book on how this particular system works so guessing I'm going to need to go get one unless someone has access to some online manuals of some sort?

 

[LCAM-01XA]

Mine just died today too! I eventually managed to get it to engage once, and that was about it. I did just swap new switches in tho, well a "new" junkyard horn pad that was in better shape than mine, and it worked just fine yesterday, guess I'll have to pull my old switches out and swap them in this thing...

 

[spencergt66]

Well i checked my switches for resistance , new vs old and they are both exactly the same I'm guessing something died like the servo or the controller no too sure where the controller is though or if its part of the servo? I went to 2 auto parts stores and looked in the books they had there ( Haynes and Chiltons) they both said bout the same thing, Dont tuch it Come on how worthless is that stupid aftermarket junk. The wireing schmatics were even more of a joke showing only engine wireing Is there anywhere i can go and get some real info thats actually useful? Anyone?

 

[spencergt66]

I almost forgot is there anyone with a 1993 F350 owners manual that can tell me what the relays and fuses are for under the hood my truck didnt come with a manual guess they lost it at some point

 

[spencergt66]

Brake switch maybe?

 

[LCAM-01XA]

Brake on-off (BOO) switch is always a suspect, but the easy check for that is to back up the truck against a wall and look for reflection of the brake lights when you step on the brake pedal - if you can see your brake lights coming on and going off, the BOO switch is good.

 

[spencergt66]

I read that theres a pressure switch in front of the booster that has issues too is this the same switch or are you talking about the one thats on the pedal?

 

[LCAM-01XA]

The BOO switch is inside the cab and under the dashboard, it sits on the brake pedal around the pin where the booster pushrod connects to. That other switch you're talking about is actually on the master cylinder, it's used to actuate the brake interlock solenoid that when disengaged prevents you from shifting out of park - basically when you push on the brake pedal and build up pressure in the master cylinder the switch there closes and powers up the interlock solenoid, that in turn allows you to shift into gear. Totally unnecessary setup IMHO, and prone to cause electric fires too, there's a TSB on that too.

 

[punkmechanic]

Im not sure on our rigs but I know on the newer ones the brake pressure switch (on the master cylinder) is tyed into the cruise control. The recall actually calls the thing a cruise control brake pressure switch, and all the recall does is put a fuse jumper harness in. The whole recall is due to the fact that the circuit to that switch is hot at all times and when the switch seal fails the brake fluid can short and start a fire. why it wasnt fuse to begin with and/or key on hot is beyond me. then again hey I just fix what the engineers cant, lol.

punk

 

[spencergt66]

So on the way to work this morning I hit the old cruise and it worked I have no idea why didnt change anything or do anything to it all yesterday so i dont know whatever seams to work for now we shall see how long this lasts

 

[Danoflapper]

I like it when things fix themselves. Hope it lasts for ya!

 

[Agnem]

Horn still works don't it? Of course it would now.... but if it fails again make sure that blows, or you won't have a complete cruise circuit.

 

[LCAM-01XA]

Well, my issue was definitely the switches - I'm running the old ones in the "new" pad now, everything works great and looks good to boot.