[tie_guy]

My cruise control on my 2008 LT2 V6 sometimes doesn't work. The problem is quiet intermittent and I knew it would be hard to get it fixed if I couldn't reproduce it in front of a mechanic. Well today I finally figured out what the problem was!

It was humid on the way home, and it was at night, so today I could tell that the cruise control sometimes doesn't turn on because sometimes the brake light goes on when I am not applying the brakes! (I could see the reflection of the center light on the condensation in the rear window)

The malfunction was actually kind of strange. If I applied the brake the light turns on, and then when I release the brake the light would turn off. However 5-6 seconds after I released the brake the light would turn back on. I did it a couple of times and then counted the time between when I let my foot off the brake and the time the light came back on and it was always almost exactly 5-6 seconds -- after that time the light would go on and stay on forever. Of course I could apply the cruise control during the 5-6 seconds while the light was off but once the light turned back on the car refused to let me turn on the cruise control (although now I am more worried about the safety issue of having my brake lights act weird.)

Another strange thing with the light is that if I just applied a little pressure to the pedal, not enough to actually slow the car down, the brake light would actually turn off. The light seemed to turn off the entire time I applied that little bit of pressure, but once I totally let up it seemed to reset the 5-6 second "clock" and then the light would just go on after that.

Anyway I am thinking that there is something messed up with the brake light switch. I am guessing that it needs to be replaced or adjusted. Can anyone give more directions on how to adjust/replace it? I am guessing the brake light activates by a simple switch but if the mechanism is more complicated (like it is computer controlled for some unknown reason) then can anyone think of something else causing a weird brake light problem?

Thanks,

Matt.

 

[Lgndryhr]

I had this same problem with mine last year. I was luckily under the 35k mile warranty. It was a brake pressure circuit. My dealership replaced the break circuit as well as replaced & recalibrated the break pedal position. It worked fine for some time after this then happened again 3 months later to be exact. The second time they cleaned and lubricated the BCM. Your cruise control is not going to work because of this as well as your break light will randomly turn on and off. I also had my ESC and Traction turn off then tell me they needed to be serviced. It first started showing signs of all this for me when my car did not shift properly at all and lag in shifting. From there the rest from above happened.

The dealer was going to replace a part that was over $1000 the second time it happened, but during the time they ordered the part and it got delivered a bulletin was submitted for my problem for them to try other methods before doing the expensive route because of obvious reasons. I told my dealership that if I ever had to return for the same thing again I expected them to fix it using the part next time since when my car came in the bulletin had not existed, and somehow they conveniently didn't call me until after it was submitted to them. I have never been happy with my dealership, but as long as I have a warranty I go there. Once my warranty expires I will stop going there. The car salesman I got my car from is great. This is the 4th car my family and I have gotten through him. The service center blows. The parts center is great. (sorry for the rant.

 

[DrivenDaily]

For tie_guy and any others wandering by:

The brake "switch" isn't a switch on the Gen7. It is actually a rheostat (variable resistor, or volume control). The BCM watches the position change and then decides if the brake lights should be illuminated or not.

I would guess it's a design to solve an issue with the only-for-2008 adjustable pedals, but they kept it as a design feature even after deleting the adjustment option. To me it means the lights don't turn on as quickly as with a switch. That delay, even if only a split second, can be the difference between a near miss and actual contact from a vehicle behind you. And here in Kentucky/Indiana (I'm right on the border in Louisville) folks are known to "drive in your trunk", or tailgate. With my own eyes I've seen a person less than a car length from the person in front - and they were doing over 60 mph! Unfortuneately that's common around here, but it's probably also common elsewhere. So the quicker you can tell the car behind you that you're slowing the better your chances are to avoid an accident.

That said, as your pedal resets in its normal resting position the material that it's made of might have a worn area that changes resistance values in such a fashion that the BCM sees it as a pedal that has moved far enough to turn on the lights. But that's just theory. You'd need to test it by putting a DVOM on the output and watching it as you drive.

 

[Chevrolet Customer Svc]

Lgndryhr,

Thank you for sharing your experience with your brake light on the Malibu. I am sure that this information will useful to a lot of members on the forum.

I am happy that your sales person is awesome.

In regards to the service department at this dealership. Would you like to provide me with additional information about this so I can document the complaints? If you would like to do this, please private message me.

Michelle, Chevrolet Customer Service

 

[Brewhaha]

The malfunction was actually kind of strange. If I applied the brake the light turns on, and then when I release the brake the light would turn off. However 5-6 seconds after I released the brake the light would turn back on. I did it a couple of times and then counted the time between when I let my foot off the brake and the time the light came back on and it was always almost exactly 5-6 seconds -- after that time the light would go on and stay on forever. Of course I could apply the cruise control during the 5-6 seconds while the light was off but once the light turned back on the car refused to let me turn on the cruise control (although now I am more worried about the safety issue of having my brake lights act weird.)

Another strange thing with the light is that if I just applied a little pressure to the pedal, not enough to actually slow the car down, the brake light would actually turn off. The light seemed to turn off the entire time I applied that little bit of pressure, but once I totally let up it seemed to reset the 5-6 second "clock" and then the light would just go on after that.

Mine started doing this last night. Thanks for posting so I have an idea of what to expect it to be when I take it to the dealership. I've had the car 2 months now and have already had several issues. This being the newest one and possibly the most dangerous I really want to get it fixed or sell the car. Don't really want to sell it, but it has already been quite the headache and money pit.

Did you get yours fixed?

Thanks.

 

[V6 Cruzer]

I am about to take my car into the dealership for a diagnostic of what is causing the brake lights to come on without pressing the brake pedal. After reading this post I am pretty sure what it is, I just hope they come to that conclusion. I asked if there was a TSB and they said no there was't any so I just hope it is not going be expensive since I have already passed the 36K warranty.

 

[Brewhaha]

Let me know how it goes, I'll be taking mine in next week hopefully.

 

[Chevrolet Customer Svc]

Dear V6 Cruzer,

I would have to agree with Brewhaha; let us know how things go at the dealership.

Sincerely,
Michelle, Chevrolet Customer Service

 

[Chevrolet Customer Svc]

Dear Brewhaha,

I hope that everything goes well when you visit the dealership next week. Please, let me know what the end result of your visit is.

Don't hesitate to contact me with questions and/or concerns.

Sincerely,
Michelle, Chevrolet Customer Service

 

[V6 Cruzer]

Well got my car back yesterday and it is fixed no more brake lights coming on by themselves. Got to say this dealership has some good people working there and I even talked to one of the mechanics telling about my problem which he knew what I was talking about. So they removed and replaced brake pedal position sensor switch, recalibrate new switch, along with road test.

 

[DrivenDaily]

Glad you had such an easy fix and a good outcome. Thanks for sharing - this just might help the next guy with this issue.

 

[l024308]

This must be a very common problem. (see thread 2009 Malibu brake light question) where I posted this same thing. My question is , Are we going to have to get this sensor replaced and adjusted every 30K miles? It seems to be a common problem. Also it sounds very similar to the problem posted in TSB 08-05-22-009 which includes some 2008 models. Mine goes to the dealer tomorrow. Will post when I find out what they do.

 

[greenman]

For future thread readers:
Replacing the brake pedal position sensor is really easy but unfortunately you still need a trip to a dealer to put a tech 2 on it to do the home position recal:
____________________________________________

Brake Pedal Position Sensor Calibration
Calibration Criteria
Important: Do not apply the brake pedal during the brake pedal position sensor calibration procedure. Any movement of the brake pedal during this procedure will cause the calibration procedure to fail. If this occurs, the brake pedal position sensor (BPPS) calibration must be repeated.

Brake pedal position sensor calibration must be performed after the brake pedal position sensor or body control module (BCM) have been serviced. The calibration procedure will set the brake pedal position sensor home value. This value is used by the BCM to determine the action of the driver applying the brake system and to provide this information to the vehicle subsystems via the GMLAN communication bus.

Calibration Procedure
Apply the parking brake.
Place the transmission in the PARK position.
Install a scan tool.
Clear all BCM DTCs before proceeding.
Navigate to the Vehicle Control Systems menu.
Select Module Setup menu item.
Select BCM menu item.
Select the BPP Sensor Calibration procedure and follow the directions displayed on the screen.

 

[DrivenDaily]

If mine ever goes out after warranty would cover it I'll replace it with a simple and common switch, then rewire the turn signals accordingly since they're affected and controlled by the BCM as well.

I believe the BPP is a left-over from the adjustable pedals that were abandoned after the 2008 MY. It adds a delay, granted only a small fraction of a second, to the process of turning on the brake lights, but there certainly have been times when a split second could have been the difference between a close call and a bump. How much does damaged paint cost? Yeah, and who does it cost?

So, mine will work one way or another. I'll see to it!

 

[greenman]

I believe the BPP is a left-over from the adjustable pedals that were abandoned after the 2008 MY.

You're right. What were they thinking with those? Much like a human appendix, nobody knows what it's for anymore. But we're stuck with it. Maybe precisely because you have to pay the dealer to calibrate a new one. Not to mention that you have to buy the OEM part (actually I'm guessing there are no third party versions-I could be wrong).

 

[l024308]

Unfortunately the Traction Control, Electronic stability control, and antilock brakes all are controled by or use the brake peddle position sensor. You would disable many important features of the car by rewiring. There has to be an easy way to adjust this without using a "Dealer only" machine. I know how to use a Multimeter. Does anyone have a setup procedure using a digital multimeter?

 

[greenman]

There has to be an easy way to adjust this without using a "Dealer only" machine. I know how to use a Multimeter. Does anyone have a setup procedure using a digital multimeter?

Not possible as it's the BCM itself that is calibrated to the new sensor's home position. You might be able to just ignore doing the recal if you don't have adjustable pedals. I've really have no idea.

 

[DrivenDaily]

Neither my '09 nor my '11 had adjustable pedals, but both inherited that freakin' BPP sensor. I didn't even think about TC or ABS.

 

[greenman]

Unfortunately the Traction Control, Electronic stability control, and antilock brakes all are controlled by or use the brake peddle position sensor. You would disable many important features of the car by rewiring.

You might well disable everything that relies on input from that sensor. There is only one BPPS output & that goes directly to the BCM. The BCM is expecting a variable voltage rising to a threshold value. When the value is met the BCM interprets that as "the brakes are applied". The BCM will then apply B+ to the stop lamps, EBCM, TCM, ECM, and stop lamp relay coil side. The only reason for that design is that the brake pedal is/was adjustable/movable. (Even though it no longer is). They probably kept the BPPS rather than having to redesign the BCM. You might be able to replace the sensor with an old-fashioned BOO switch but in my humble opinion, life's way too short. It's not that I'm not game for experimenting though.

 

[DrivenDaily]

Well, if the "simple" thing the BCM does is determine when to turn on the lights and then supply a B+ to those various items, I can get one or two relays (DPDT, 4PDT, etc) to trigger when the BOO turns the lights on, and then the contacts that close will supply B+ to the appropriate inputs. If it truly is that simple then that would be nice, eh?

But as I said above, I'd have to also modify the MFS to make the signals work, but that's an easy fix compared to the rest. Two DPDT relays would suffice, then grab the output from the hazard switch through 2 diodes and Voila!