Cruise control won't turn off!
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October 2009 ROTM
October 2009 ROTM
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I'm guessing by DMV you mean NHTSA. If DMVs made design rules we would have 50 different sets.
As for Cruise system power, 12v is supplied directly from the fuse block to the module any time ignition is on. The same fuse sends a 12v signal through the brake (and clutch if applicable). Depressing the pedal removed that input (cruise cancel). A third 12v supply is sent through the stalk switch when cruise switch is on. (Based on Page 8-714 of my FSM)
So pressing the clutch or brake pedal still leaves 2 valid 12v power sources going to a malfunctioning cruise control module. The CCM is designed to always fail in a disable mode. But 30+ years in aircraft electronics has shown me any circuit can have unintended behaviors.
As for Cruise system power, 12v is supplied directly from the fuse block to the module any time ignition is on. The same fuse sends a 12v signal through the brake (and clutch if applicable). Depressing the pedal removed that input (cruise cancel). A third 12v supply is sent through the stalk switch when cruise switch is on. (Based on Page 8-714 of my FSM)
So pressing the clutch or brake pedal still leaves 2 valid 12v power sources going to a malfunctioning cruise control module. The CCM is designed to always fail in a disable mode. But 30+ years in aircraft electronics has shown me any circuit can have unintended behaviors.
In almost 30 years in the industry I can not remember even hearing of a Cruise unit stuck on to the point the fuse had to be pulled. DOT gets complaint of cars running amuck all the time. It is basically people panicking and thinking the car is going on its own. Problem with the complaint is the DOT has been getting them for decades and there has been "statistically" just as many people have complained about this on car without cruise control. To actually have one still stuck while the car was stopped is amazing, if the car was even close to being new I am sure GM would swap the unit for free one just to figure out what happened. I would disconnect the cable ASAP.
I think there was some real cruise issues in the pass but never on a large scale for GM that I am aware of.
Last edited by Gorn; Jan 19, 2014 at 06:45 PM.
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2nd Gear member
Joined: Dec 2011
Posts: 393
From: Virginia
Is the cable you are talking about one of the two going to the throttle body area? Which one is the right one to disconnect until I can get it to the shop because the fuse I pulled was for the AC as well, might need the defroster to work.
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Joined: Sep 2013
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Definitely disconnect the actuator cable at the throttle body. if the CCM is acting up it could actuate the throttle at any time.
I went back and looked at the schematic and along with the cruise disable switch at the brake pedal the brake light on switch is also sent to the CCM. So the brake pedal has two disable signals.
As far as I can tell, the CCM is the only part that could cause the malfunction.
Also report it to the NHTSA. If there have been other incidents they will know.
I went back and looked at the schematic and along with the cruise disable switch at the brake pedal the brake light on switch is also sent to the CCM. So the brake pedal has two disable signals.
As far as I can tell, the CCM is the only part that could cause the malfunction.
Also report it to the NHTSA. If there have been other incidents they will know.
Fourth Generation Moderator
October 2009 ROTM
October 2009 ROTM
iTrader: (1)
Joined: Nov 2007
Posts: 10,560
From: Eastern PA,
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Trace the cables back, One goes to the fire wall the other one does a loop around and heads towards the front of the car along the inner fender. The one that loops it the cruise control, the one that goes to the fire wall is your gas petal. If you get it wrong the car wont go, then just switch them.
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