# Cruise control quit on the 02 F150



## luke strawwalker (Jul 31, 2014)

Worked fine driving up to Indiana. Then I went on a parts run the other day and the darn thing quit altogether. I noticed it'd been acting up for awhile, taking a long time and several attempts to get it to turn on and take over.

Having finished planting Saturday and after cleaning up and putting away equipment today, taking back leftover seed and skids, and pressure washing the tractors, and after having done some research on it on the internet, I went over to the shop today and started troubleshooting it.

Turns out the F-150's usually have a recall part installed to fix a fire risk in the truck through bad design. Apparently, the geniuses who designed the trucks fed power all the time to a brake fluid pressure switch on the master cylinder that would, over time, start to leak, get soaked in brake fluid, and then short out the harness and burn the truck to the ground, and take people's house with it if it were parked in the garage. Ford recalled them and installed a fusible link plugged in to the switch, with the switch plug plugged into the fusible link. Thing was, they used cheap fusible links and they're apparently notorious for going out and leaving you with no power to the cruise system. Also, they'd replace the pressure switches if they were leaking, but they used some cheap junk switches that were quite likely to go out again. So these two items are the #1 things to check as they're the usual culprit. The switch should have power 100% of the time, and the switch should be closed and conducting current at all times until the brakes are depressed hard enough to create 125 psi in the brake lines, at which point the switch opens.

Well, a quick test showed I had 12 volts in the harness and the switch was working properly. A little more research had revealed that the #2 most likely problem was the buttons and/or "clock spring", a band of wiring behind the steering wheel that replaced the old sliding horn contact rings present on old vehicles. I took the airbag out of the wheel and pulled the switches, and started testing them. Come to find out, Ford does not make the switches hermetically sealed-- they're just a stupid little circuit board inside the plastic button housing, with a little bit of spring steel that snaps over the contacts, which are a couple tiny little "cat hair" sized copper contacts that the curved spring steel "pops down inside out" against when you depress the button, closing the circuit. Once I figured out which wires did what, I tested the function of the buttons and their resistance, which signals the speed control servo what to do. Turns out the "ON" button wasn't closing. I took the switch apart, since even on Ebay the switches run about $150 bucks MINIMUM, and cleaned the contacts with my knife (they were cruddy and tarnished) and cleaned up the steel spring button contactor. I put it back together and found I was still not getting contact, so I pulled the steel contactor back off it and bent the copper contacts up just a bit, then put it back together and tested it again. I got continuity when pressing the button and an open circuit when I let off the button, but the ohm test showed zero ohms, when there's supposed to be a 1000 ohm resistor inline with it. I did a little more testing to see if I could figure out if the resistor was shorted or what, but basically it's all tinker-toy stuff machine soldered and embedded in a little plastic chip about 2 inches long and 3/4 of an inch wide inside the switch, so there wasn't much I could do. Put it back together and gave it a test drive. Works like a champ.

I like it when I don't have to buy a $200 switch...

Thing is, the switches had a lot of dust and crud in them. Typical that they'd make the things totally unsealed against any kind of dust or crud getting in there.

Later! OL J R


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## mlappin (Jun 25, 2009)

Dad had a Dodge the cruise quit, had a weird speedo sensor, one wire fed the speedo, the other was for the cruise, the cruise part can die but the speedo will still work.

Had to pull the airbag on my cummins when I got it, power wire to the cruise switch was broke.


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