[jrsmith]

Looking for some help diagnosing a P0573 (TCM) Cruise Control Brake Switch Circuit High Voltage DTC. Cruise control simply will not enable. I've already replaced the brake position sensor, getting the same DTC coming back after clearing & doing a BPP relearn. I've got some screenshots of my Tech2; can someone verify the voltages look ok? Any other suggestions would be appreciated. I've even tried clearing the DTC while the vehicle is driving down the road, comes right back after I try and activate cruise.

DTC Info:

BPP Sensor Info:

Cruise Control Data:

 

[CodyATE6]

I’ll have to look and see if I can get into the read outs for the cruise control with my scanner. I will compare the voltages if I can.

 

[CodyATE6]

I might have to go back to look for the pedal switch voltage since I didn’t find it. Im sure it’s in there, but it’d only tell me it was open or closed circuit.

I got these reading from the cruise switch. From what I see your car pretty much matches mine. Car is an ‘06 LT sedan.

 

[jrsmith]

Thanks. One thing someone told me is that there is a second "Cruise cancel" switch connected to the brake pedal somewhere. I can't see it though, is there a diagram of where it is?

Edit: guess I was overthinking this...turns out all 3 of my upper brake lights were burned out! I guess that also triggers that DTC.

 

[CodyATE6]

The ones in the trunk lid? I have noticed they are on a separate circuit than the tail light bulbs. So if the key is off the third brake light can still come on but not the tail lights if you hold the brakes. I might have to try removing the bulbs and see what happens. I have leds in mine and am kind of surprised they didn’t cause a problem with the cruise working.

 

[blu3_v1p3r]

Thanks. One thing someone told me is that there is a second "Cruise cancel" switch connected to the brake pedal somewhere. I can't see it though, is there a diagram of where it is?

Edit: guess I was overthinking this...turns out all 3 of my upper brake lights were burned out! I guess that also triggers that DTC.

I was going to mention break lights, but I guess I assumed that since you had the readouts and all the informationo you had that you had already checked that. Its kinda weird though, I have had my 3rd break light disconnected and for got plug it back in and did pop a code for it. My cruise just didn't work.

 

[1966tbird]

Did you verify all 3 of your 3rd brake lights are working?

 

[1966tbird]

Oops. Slow read. Looks like you may have found it

 

[RH45]

Thanks. One thing someone told me is that there is a second "Cruise cancel" switch connected to the brake pedal somewhere. I can't see it though, is there a diagram of where it is?

Edit: guess I was overthinking this...turns out all 3 of my upper brake lights were burned out! I guess that also triggers that DTC.

My stepdaughter's cruise quit working even though the light was on, it wouldn't "set"
I told her to try to pull the brake pedal up, with her toes, and try it again, but, it still wouldn't set.
I'm glad I did a search, here, before tearing into it. I never would have guessed that burned out bulbs, in the third brake light would keep the cruise from being able to set.
Thanks for the great information!!

 

[rk777er]

so i have a 2005 chevy malibu. same problem. i notice my 3rd brake light works with key in accessory postion but goes out when key is on or car running? how can it work with car not running then when you start car it doesn't work? i think this has something to do with me having code PO573 and cruse doesn't work either? did you ever figure your problem out?

 

[willspeed]

The fun part is that my Cobalt 2009 doesn't even have cruise control, yet, I also have the PO573 and hoping for your help.

Very recently I changed the bulbs of the (center high mount stop, or) third trunk-lid brake light from stock to LED. The reason was that stock bulbs were burning straight through their plastic PE sockets. That seems to be a common problem as it was very hard to find a good ones at the car recycler.

My question is: could a change from stock bulbs (T5, 12DC, 13W) to LED (T10, 12DC, 2.4W) trigger the P0573? The LEDs obviously draw a fraction compared to the stock, a difference of 1.08AMP versus 0.24AMP. Could that be a reason for the 'high voltage' code? What are your ideas?