Cruise Control Kicking On By Itself

[Woody35]

Recently the truck after traveling at higher speeds (60 mph+) the cruise control will kick on by itself after I have took my foot off the pedal. This only happens when I let the truck slow down without the brakes and the cruise control switch is on the on position. I will add that during the time I am driving at these higher speeds I never engage the cruise control before it kicks on by itself.

After I let off the pedal the truck hesitates for a moment and then accelerates to the speed I was at. But as soon as I touch the brake pedal it kicks off and goes back to idle. Everything else about the truck is normal and I dont have any codes. I put the switch on the off position and it hasnt happened since but it is a little unnerving knowing your vehicle could possibly start accelerating by itself. Any ideas on what the problem could be? Thanks for the help.

 

[WarWagon]

I'd replace the stalk with the cruise control switch and wire down to the dash through the column. (Same part) The switch is bad or a wire is shorting to turn it on. Most likely to have failed.
Possible ECM failure to kick it on as well.
You have checked grounds, battery condition and alternator for shorted diodes/excess noise as these are remote possibilities. A scanner looking at ECM voltage could tell you if that was low from a bad ignition switch etc. Also check for codes...

 

[largelybored]

There is a youtube video showing the procedure to replace that switch. It is a little bit involved but you'll save a lot of money. It is called the multi-function switch.

How To Install Replace PART 1 Turn Signal Wiper Switch Chevy GMC Pickup Truck 88-98 1AAuto.com
http://www.youtube.com/watch?v=Bkt9tfgJFdI

After I replaced the switch my cruise was working properly, and then a few months later I got unintended acceleration, which turned out to be the PMD.

 

[Burning oil]

I was just going to say do you have a different PMD you can try first?

 

[Woody35]

I was just going to say do you have a different PMD you can try first?

Well the dealer decided to plug in the new pmd in the stock location after my inj pump died. so it would be hard to unplug it with my fat fingers to plug the pmd i got from you that is on the bumper but if this problem does get worse I will try it.

There is a youtube video showing the procedure to replace that switch. It is a little bit involved but you'll save a lot of money. It is called the multi-function switch.
After I replaced the switch my cruise was working properly, and then a few months later I got unintended acceleration, which turned out to be the PMD.

Thanks for the video. The problem is the truck doesnt accerlate at full throttle which im pretty sure is the sympton that most problematic pmds have. It just gradually accelerates to the speed I was at before

I'd replace the stalk with the cruise control switch and wire down to the dash through the column. (Same part) The switch is bad or a wire is shorting to turn it on. Most likely to have failed.
Possible ECM failure to kick it on as well.
You have checked grounds, battery condition and alternator for shorted diodes/excess noise as these are remote possibilities. A scanner looking at ECM voltage could tell you if that was low from a bad ignition switch etc. Also check for codes...

Hooked up a Tech 2 in my auto class and it has no codes. ECM voltage was normal my teacher said. BTW does anyone know if ALLDATA or mitchell would have any better diagrams or schematics for diesels if I looked up under a 2500 or 3500? Or if it would be similar to a 1500? When I was looking up wiring diagrams and locations for my truck it kept giving me part locations for gas 1500s not diesel so now I am suspecting a lot of the wiring diagrams could be wrong too. My teacher also said it could be a bad ECM or the wiring. The problem is this happens at random and I cannot get it to do it again which makes it hard to diagnose it

 

[WarWagon]

This acts like the resume switch is being pressed, wire for switch shorting, or the like. In this case I would throw parts at it being the stalk, multifunction lever. These go bad often. The dealer has a special tool to monitor cruise switches or at least for 1993's with the cable box drive.

Intermittent is likely a wire that gets replaced with the stalk anyway.

Your system is an electronic throttle so the ECM controls the cruise. So stalk, check other wires, then replace ECM.

You have dissembled the ECM ground by the trans dipstick and cleaned it, right?

 

[Woody35]

Yes I cleaned all the grounds near and around the intake. If this starts to happen reguarly I will look into replacing the multifunction lever and will go from there. Thanks for the help guys!