Cruise Control Problem

[rvassar]

I've had some problems with my wife's 7.3l Excursion. I've had two incidents where I was running in cruse and had to hit the brakes, and found myself fighting to throttle. The first time was last fall, person in front of me decided to make a surprise unsignaled right turn and I had to get her stopped... I'm pretty sure I thumbed the off button, but things were getting just a bit exciting, as I had to start correcting for the torque induced frame flex... I ended up cutting the ignition.

Last saturday it happened again. This time I had more time. I had the brake applied, and the engine started to spool up. I hit the off button and held it, no change. I then started hunting around the off switch, trying to rock it from left to right, trying to find a good contact patch. At the same time, I pressed "coast". This seemed to do the trick, and she dropped the throttle.

I took it to the dealer yesterday, and had them try and diagnose it. They were unable to reproduce the problem. They even admitted they drove it all the way over to Taylor for lunch trying to reproduce it. (and didn't even save me any BBQ!) They don't see any point in throwing parts at it, so it's back in the driveway.

I'm at a loss. It seems to be a triple failure. The brake light switch, the hydraulic backup, and the steering wheel switch. There's no servo to stick. All of this points at the PCM.


Anyone have any ideas?

 

[Max Power]

For the price of a brake switch I would replace that.

 

[jlayne]

what about the switch for the brake lights under the dash... doesn't that kick the cruise off... shouldn't be very expensive

what color is you excursion so i don't get infront of you? good luck

 

[RenoF250]

I've had some problems with my wife's 7.3l Excursion. I've had two incidents where I was running in cruse and had to hit the brakes, and found myself fighting to throttle. The first time was last fall, person in front of me decided to make a surprise unsignaled right turn and I had to get her stopped... I'm pretty sure I thumbed the off button, but things were getting just a bit exciting, as I had to start correcting for the torque induced frame flex... I ended up cutting the ignition.

Last saturday it happened again. This time I had more time. I had the brake applied, and the engine started to spool up. I hit the off button and held it, no change. I then started hunting around the off switch, trying to rock it from left to right, trying to find a good contact patch. At the same time, I pressed "coast". This seemed to do the trick, and she dropped the throttle.

I took it to the dealer yesterday, and had them try and diagnose it. They were unable to reproduce the problem. They even admitted they drove it all the way over to Taylor for lunch trying to reproduce it. (and didn't even save me any BBQ!) They don't see any point in throwing parts at it, so it's back in the driveway.

I'm at a loss. It seems to be a triple failure. The brake light switch, the hydraulic backup, and the steering wheel switch. There's no servo to stick. All of this points at the PCM.


Anyone have any ideas?

The reason the dealer could not recreate it is there was no one stopping in front of them. You should have driven around in front of them doing panic stops and I am sure it would have done it right away. If neither the off switch or the brake is deactivating it I would guess that it is not a switch problem. Seems to me it would be a PCM problem but I would have hoped the engineers at Ford would have designed it so that this could not happen.

 

[Max Power]

Older cruise systems used to have a dual system on the brake switch. One electric and one vaccum. They've gone away from that and it is realy too bad.

 

[trackspeeder]

If you have the adjustable pedal option, have it checked out.

 

[kwazyca]

Is the vehicle still under warranty?

Just tell the dealer you will hold them legally liable if you get into an accident. Send that to them registered mail.

Believe me, they will quickly start "throwing parts" at it.

FWIW,

Tom

 

[rvassar]

Nope... It's out of warranty, and has the fixed pedals.

 

[Bushhog]

"I'm at a loss. It seems to be a triple failure. The brake light switch, the hydraulic backup, and the steering wheel switch. There's no servo to stick. All of this points at the PCM."

rvassar

I had a problem with my cruse when I first got my 2000 F350 and it was the PCM.

But!!! If I were having trouble with any cruse on a Ford right now I would change that brake fluid operated switch. I just don't believe they know where the put all the faulty ones.

 

[Ramprat]

We were having problems with our cruse control also. However, while the buttons in the steering wheel don't seem to always work the pedal cut outs are working great

On the truck I need to pus the buttons mutipal times & then finally they seem to work if they feel like it.

 

[rvassar]

We were having problems with our cruse control also. However, while the buttons in the steering wheel don't seem to always work the pedal cut outs are working great

On the truck I need to pus the buttons mutipal times & then finally they seem to work if they feel like it.

I've been looking at the wring diagram. The steering wheel buttons are kind of funny. It looks like the engineers were trying to save pins on the PCM. The switches actually connect various resistors to the PCM inputs, so "coast" is 120 ohms, "set" is 680 ohms, "off" is a dead short, and "on" gets crossed up with the horn somehow.

 

[DieselFreak77]

Ramprat, I was having the same issue with my cruise control and then it just stopped workign one day. I haven't had time to look into it.

 

[NJKen]

I've been looking at the wring diagram. The steering wheel buttons are kind of funny. It looks like the engineers were trying to save pins on the PCM. The switches actually connect various resistors to the PCM inputs, so "coast" is 120 ohms, "set" is 680 ohms, "off" is a dead short, and "on" gets crossed up with the horn somehow.

Thats how Ford has done it for years. Any dirt in the contacts will make cruise act weird.
Thst is truly a weird problem you are having. I would change the brakelight switch just as a preaution. They are not too expensive and it is the most likely cause of your problem.
Good Luck
Ken