AlexLok96

Hello
My 2009 Uplander LT EXT (has 159 000 kms) has been driving perfectly up until today. The traction control light is on, along with "service traction control system" and "service stability system" messages on the DIC. The funny thing is that when these messages come on, they come on while braking, and the brake pedal goes to the floor, and you have no brakes unless you release the pedal and press again. With the messages on, you can drive the van with normal brakes but at random, the pedal will drop to the floor, leaving you in some potentially bad situation with almost no brakes. Once you shut off the van, the messages go away and it goes back to normal at the next startup, but will come back again soon while driving.

Has anyone experienced this before? I want to assume its an electrical problem?

I have new brakes all round on the van, and 2 new rear calipers installed during February, and have bled the brake system a total of 3 times.The brakes were perfect up until today.

I know that if it was speed the sensor in the hub, the abs, traction, stability and traction lights would be on, so I don't think its that.

AlexLok96

Hey,
I got the problem fixed. It turns out that when I replaced the rear calipers and bled the system, I had topped it off with prestone DOT 3 SYNTHETIC brake fluid which, when mixed with the regular DOT 3 stuff already in there, caused the seals in the master cylinder to go bad, causing the lights and messages to show up, along with the pedal sucking to the floor. Also a CO131 code was retrieved from the van, stating a pressure fault.
So Now with a new master cylinder from gm, brakes are operating as they should. Hope this helps someone in the future.

niceguy88

Thanks for the update, I didn't even know they made synthetic brake fluid. But I did figure out in the past that the Stability Control/Traction Service lights will be displayed if the brake fluid level is too high or low