Discovered A new way to cancel Cruise Control.

[okfoz]

Yesterday I was on the highway with my 2007 Tahoe LTZ. The Cruise was set and all was great. I thought I could hear some window noise like one of the windows were down, but I did not know which one, so I pulled up on all of the switches, and then I started to slow down...

Puzzled, I looked at my IP and sure enough the Cruise light was not illuminated, so I hit resume and went on my way. I started thinking, "what caused my cruise to turn off?" I did not hit the brake or the Cancel button on the Steering wheel. So I started to play around again to see what I did.

As it turns out, if the windows are all the way up, and I pull up on any TWO switches the cruise will cancel. It does not seem to matter if it was the front windows, the back windows, the two right windows, etc. One window would not do it, but two at the same time will, every time. It is very repeatable, did it on the way into work this morning just to see, did not matter what speed I was at, 40mph, 70mph.

Anyone else ever experience this? It is not huge, but a bit concerning honestly as I ask myself if it is a precursor to something else coming down the pike.

The only possibilities that I can think of is
1) There was a power drop when I pulled up two windows at the same time, causing my cruise to cancel. But the IP lights did not appear to dim.
2) The windows use the data-line like everything else in the car, and the act of pulling up on two windows at the same time is the same signal as the cruise signal. This would ring true, but the cruise does not cancel If I roll two windows up at the same time when they are down.

John

 

[iamdub]

The only possibilities that I can think of is
1) There was a power drop when I pulled up two windows at the same time, causing my cruise to cancel. But the IP lights did not appear to dim.
2) The windows use the data-line like everything else in the car, and the act of pulling up on two windows at the same time is the same signal as the cruise signal. This would ring true, but the cruise does not cancel If I roll two windows up at the same time when they are down.

John

I suspect it's a power draw issue. The voltage drops enough that the BCM or whatever has it's hand in controlling the windows reacts and cancelling the cruise is one of the reactions. Could it be a problem of a weak charging system? Maybe. Or maybe it's just inherent of the design and is unintentional and harmless. I was gonna suggest simultaneously rolling up on two windows from their down position to test this theory, but you already have and confirmed it. True, the windows (technically their relays) are switched by a Class 3 data bus, but the window motors themselves pull considerable amperage so they are powered off of larger circuits directly off of the fuse/relay center. Maybe a few other members can try theirs to see if it does the same. If not, maybe they can try 3 or all four windows simultaneously to try to replicate it. If it seems common across the board, I'd say it's just a harmless inherent design. If it's isolated to yours or a very few members, then maybe you and them have slightly weak charging systems. But, there are so many other factors involved with other vehicles such as added accessories, different alternators, different batteries, operating temperatures, condition of charging system components and those components drawing off the charging system, etc.

 

[okfoz]

iamdub,
Thanks for your thoughts. It seems to have gotten even more strange. If my lights are on, cruise does not cancel with the window switches... The lights will dim a little on the dash and the headlights will dim, but it does not cancel it. That seems to be my suspicion as well that the drain somehow causes the cruise to cancel.

Note: My DRL have not worked for years, I refuse to remove the bumper to replace the bulbs at this point. I will do that when a blinker or headlight goes out.

I do have an aftermarket subwoofer under my center console, with a remote amp, this might be a clue to something, maybe I will try turning off my radio and all of the accessories and see what happens. Then try it with everything on like heated seats, rear blower and the works to see if there is a change.

Even with that, why it would not work with my lights ON is beyond me.

John

 

[swathdiver]

I've never been able to do that with mine and always check them that way, pulling up on the pairs to seat the windows usually because of the kids. I think your BCM is on the fritz.

 

[sk1dm4rk]

I concur. I tested this this morning and tried all possible combinations and no cruise cancellation.

 

[okfoz]

If I remember, I will run my scanner on it tonight to see if there are any codes... It is odd indeed.

Are the windows even connected to the BCM? The auto down feature used to be actually in the switch itself, and what caused them to stop was the motor puts out more load when the windows do not move, the switch would sense this and stop the window. I remember people taking switches from the early 90's Saturns and putting them in 3rd gen Firebird and Camaros and they would get the auto down feature. I would not think There is a reason to have it connected to the BCM, it is not like I have remote windows, but with everything today in a modern car everything is controlled by a computer. Even things that for a century didn't need to be.

 

[MidwestMike]

I suspect it's a power draw issue. The voltage drops enough that the BCM or whatever has it's hand in controlling the windows reacts and cancelling the cruise is one of the reactions.

If that was the case, wouldn't you be able to repeat the results by pushing down when the windows were already down?
(or is the thinking that there is a limit switch involved in going down, but not up? )

 

[Doubeleive]

iamdub,
Thanks for your thoughts. It seems to have gotten even more strange. If my lights are on, cruise does not cancel with the window switches... The lights will dim a little on the dash and the headlights will dim, but it does not cancel it. That seems to be my suspicion as well that the drain somehow causes the cruise to cancel.

Note: My DRL have not worked for years, I refuse to remove the bumper to replace the bulbs at this point. I will do that when a blinker or headlight goes out.

I do have an aftermarket subwoofer under my center console, with a remote amp, this might be a clue to something, maybe I will try turning off my radio and all of the accessories and see what happens. Then try it with everything on like heated seats, rear blower and the works to see if there is a change.

Even with that, why it would not work with my lights ON is beyond me.

iamdub,
Thanks for your thoughts. It seems to have gotten even more strange. If my lights are on, cruise does not cancel with the window switches... The lights will dim a little on the dash and the headlights will dim, but it does not cancel it. That seems to be my suspicion as well that the drain somehow causes the cruise to cancel.

Note: My DRL have not worked for years, I refuse to remove the bumper to replace the bulbs at this point. I will do that when a blinker or headlight goes out.

I do have an aftermarket subwoofer under my center console, with a remote amp, this might be a clue to something, maybe I will try turning off my radio and all of the accessories and see what happens. Then try it with everything on like heated seats, rear blower and the works to see if there is a change.

Even with that, why it would not work with my lights ON is beyond me.

John

John

you don't need to remove your bumper to change your bulbs, it takes about 10 minutes once you have done it a couple times, just remove the two bolts from the top of the housing with hood open, remove the front top grill bolts across the whole top side, go over to the left or right side remove the one bolt that is in the wheel liner about 3/4 way from top of tire, once that is removed you can pull the plastic shroud back by hand and reach inside with a 10mm and remove the last nut, then just pull the housing forward because the grill side will give you room since it is loosened and presto you can change any or all bulbs, install is the reverse. I have done it multiple times it gets easier every time. no sense in removing a entire bumper that's just crazy.

 

[Doubeleive]

I will try that today and see if get the same results with the cruise control

 

[iamdub]

If that was the case, wouldn't you be able to repeat the results by pushing down when the windows were already down?
(or is the thinking that there is a limit switch involved in going down, but not up? )

Not as likely. The window motors are under much less strain going down because they're not having to push up on the glass against gravity. Yes, the regulator has a spring so the motor isn't moving all the window's weight, but it's not a perfect balance.