What would make cruise control turn off?

[Dustin Jackson]

When I first bought my Tahoe cruise control didn't work and I had the dealership fix it before I took the Tahoe. Cruise control has worked great ever since and has only turned off on me 2 times unexpectedly..

The first was when my lifter failed, I was driving with cruise control on and then it turned off with a flashing check engine light.

The last time cruise control turned off unexpectedly I was driving with cruise control and it just turned off but nothing was wrong with the Tahoe, I turned cruise control back on and no drama ever since.

What parameters trigger cruise control to turn off?

 

[donjetman]

brake light switch at the pedal
I had to replace it to get the cruise control to work.

 

[Geotrash]

brale light switch at the pedal
I had to replace it to get the cruise control to work.

+1. Had to replace the one on my '07 as well.

 

[swathdiver]

My cruise didn't work until the brake pedal switch was replaced.

Don't try to fix it, just replace it. I keep a spare on the shelf. Both numbers on the box/wrapping.

 

[Dustin Jackson]

If I was sure that it was the brake pedal switch I would have no problem going for it but I’ve only had it happen once and hasn’t happened since

 

[iamdub]

If I was sure that it was the brake pedal switch I would have no problem going for it but I’ve only had it happen once and hasn’t happened since

Give it a few more months or year, maybe when the weather changes. It'll begin to happen more often. When it gets to the point where it won't set or immediately disengages, jab the brake pedal then lift up on it with your foot behind it and see if you can set your cruise. Then, find this thread and scroll back up to @swathdiver's post where he so graciously provided you a part number and shop for one, hoping the price hasn't tripled by then.

 

[Dustin Jackson]

You guys are usually not quick to resort to throwing parts at the problem so I’m sure there’s a good a reason for it but it hasn’t been explained to me yet.

I hope you can understand my caution to throwing my wallet at the problem without a little investigation, I would be surprised if there is literally no other reason cruise control would disengage other than a faulty brake pedal switch but that hasn’t been explained.

The first time my cruise control disengaged was accompanied by a check engine light so I know there are other parameters that can have influence on cruise control operation.

Also stated in my initial post the brake pedal switch was replaced when I bought my Tahoe 4 years ago

 

[swathdiver]

You guys are usually not quick to resort to throwing parts at the problem so I’m sure there’s a good a reason for it but it hasn’t been explained to me yet.

I hope you can understand my caution to throwing my wallet at the problem without a little investigation, I would be surprised if there is literally no other reason cruise control would disengage other than a faulty brake pedal switch but that hasn’t been explained.

The first time my cruise control disengaged was accompanied by a check engine light so I know there are other parameters that can have influence on cruise control operation.

Also stated in my initial post the brake pedal switch was replaced when I bought my Tahoe 4 years ago

It's $16 on Amazon Dustin. If the amber light does not come on when you press the button on the steering wheel it could be something else. A DTC often disables cruise control so as not to damage the engine. The switch is the culprit 95% of the time. My new SSR for the trailer brakes went bad and it too was replaced 4 years ago.

 

[Geotrash]

Here's the info on what will cause the cruise control to disengage from alldatadiy (subscription highly recommended - I use it all the time). I emphasized the part below that says that the reason for the last 8 times the cruise control was disengaged will be logged within the ECM memory so you can use your scanner to figure it out if it happens again. BUT...it's the brake light switch :


Cruise Control Disengaged

The engine control module (ECM) disengages the cruise control operation based on the signals from the following switches:

• The stop lamp switch
• The cruise control On/Off switch
• The cruise control cancel switch

The body control module (BCM) determines when the cruise control cancel switch is activated. When the normally open cancel switch is closed, the BCM detects the predetermined voltage signal on the cruise control function switch circuit. The BCM sends a GMLAN serial data message to the ECM in order to disengage the cruise control system.

The stop lamp switch is mounted on the brake pedal bracket. When the brake pedal is applied, the normally open stop lamp switch closes. The ECM monitors the stop lamp signal circuit through a discrete input and a GMLAN serial data message signal from the BCM indicating the brake status. When both signals indicate the brake pedal is applied, the ECM will disengage the cruise control system.

The Cruise Control System will disengage when the cruise control on/off switch is switched OFF. The vehicle speed stored in the memory of the engine control module will be erased when the cruise control On/Off switch is turned OFF, or the ignition switch is turned OFF.

The Cruise Control System will disengage when the ECM detects that a driver override function has been active for approximately 60 seconds. When the Cruise Control System has been disengaged, the ECM sends a GMLAN serial message to the instrument panel cluster (IPC) in order to turn OFF the Cruise Engaged indicator, and to the driver information center (DIC) in order to turn OFF the CRUISE SET TO ### message.

*******Each time the Cruise Control System is disengaged, the ECM will keep track of the reason for system disengagement. The last 8 disengagement reasons will be recorded within the ECM memory, and can be viewed with a scan tool.*******

Cruise Control Inhibited

The engine control module (ECM) inhibits the cruise control operation when any of the following conditions exist:

• The ECM has not detected a brake pedal activation from the body control module (BCM).
• A Cruise Control System DTC has been set.
• The vehicle speed is less than 40.2 km/h (25 mph).
• The vehicle speed is too high.
• The vehicle is in PARK, REVERSE, NEUTRAL, or 1st gear.
• The engine RPM is too low.
• The engine RPM is too high.
• The system voltage is not between 9-16 volts.
• The Antilock Brake System (ABS)/Traction Control System (TCS) is active for more than 2 seconds.

 

[Dustin Jackson]

That's good literature @Geotrash thank you for that

 

[Geotrash]

That's good literature @Geotrash thank you for that

Happy to help, and of course the subtext to all of that is that any electrical problems in connectivity, resistance in the wiring, bad grounds, etc. would all need to be troubleshot using a methodical process if after all of the items above have been conclusively ruled out as culprits. Alldata provides a guide for that in the Cruise Control section of the manual.

 

[Dustin Jackson]

I appreciate it, I think I've annoyed enough people with my "how does it work" questions for the time being lol

 

[iamdub]

You guys are usually not quick to resort to throwing parts at the problem so I’m sure there’s a good a reason for it but it hasn’t been explained to me yet.

I hope you can understand my caution to throwing my wallet at the problem without a little investigation, I would be surprised if there is literally no other reason cruise control would disengage other than a faulty brake pedal switch but that hasn’t been explained.

The first time my cruise control disengaged was accompanied by a check engine light so I know there are other parameters that can have influence on cruise control operation.

Also stated in my initial post the brake pedal switch was replaced when I bought my Tahoe 4 years ago

It's such a commonly failing part that, with no other symptoms pointing elsewhere, it's worth throwing the $16 and 10 minutes at. You're correct that there are other causes for the cruise to disengage and/or not set. As they said, it is automatically disabled when there's a drivabilty and/or safety (Traction Control, StabiliTrak, etc.) concern. Look at it from the other way: What if you went on a deep dive checking circuits, troubleshooting modules, sensors and switches and still drew a blank? THEN you replaced the switch and the issue never happened again? You'd be aggravated that you wasted a whole weekend crawling through your Tahoe when all you needed was 10 minutes to lay in the floorboard.

It's not a critical system and you could wait until it does it more frequently if you wanna get every cent out of the current switch. Speaking of, is it an OEM switch or aftermarket? If it starts happening more often, try those tests I listed to help confirm.

 

[Geotrash]

As they said, it is automatically disabled when there's a drivabilty and/or safety (Traction Control, StabiliTrak, etc.) concern.

100% agree with everything else you said but just one small clarification on this point. StabiliTrak and Traction Control faults won't prevent the cruise control from working. It's not listed in the disablers for the cruise in the troubleshooting guide, and the steering position sensor on my '07 has been throwing a Stab/TC light for a couple of years now and the TC still works fine.

 

[Dustin Jackson]

@iamdub @swathdiver I appreciate it guys, not so much of a problem yet just educating myself. The only other time cruise control shut off on me was when my lifter failed as you could imagine I just about shat my pants when cruise control turned off again unexpectedly

 

[iamdub]

100% agree with everything else you said but just one small clarification on this point. StabiliTrak and Traction Control faults won't prevent the cruise control from working. It's not listed in the disablers for the cruise in the troubleshooting guide, and the steering position sensor on my '07 has been throwing a Stab/TC light for a couple of years now and the TC still works fine.

Thanks for clarifying. Now that you mention it and that I think about it further, those times the CC wouldn't set and the TC and ST warnings must not have been directly related but both the results of a failure further up the chain. It's been too long for me to remember exactly what it was, but I recall it was a sensor issue.

To reinforce your clarification and dope slap myself, my TC and ST warnings are still on due to that dead rear speed sensor I haven't bothered to replace. My CC works fine.

 

[Geotrash]

Thanks for clarifying. Now that you mention it and that I think about it further, those times the CC wouldn't set and the TC and ST warnings must not have been directly related but both the results of a failure further up the chain. It's been too long for me to remember exactly what it was, but I recall it was a sensor issue.

To reinforce your clarification and dope slap myself, my TC and ST warnings are still on due to that dead rear speed sensor I haven't bothered to replace. My CC works fine.

Yeah, a misfire code would deactivate the CC, for sure. And I'm with ya - replacing that steering angle sensor isn't that hard, but it's just enough of a pain in the a$$ that I keep procrastinating about it.

 

[DaDenaliDude]

Brake light switch would be the first thing I’d try. When I bought my 07 Denali it wasn’t working and I replaced that part and it’s been working ever since. 20 minute job and the part is like $25.