Does a regular brake bleeding procedure require the battery to be disconnected? I bled the brakes on my 2014 LS yesterday and had a surprise. With the engine and ignition off, I cracked the rear right bleeder and began to slowly pump the brake pedal when what I assume is the brake booster pump kicked on, I heard a groaning and some clicking, and then pop sound. Freaked me out. I checked my self-bleeder and the silicone hose had popped off of the bleeder screw. It was like the pump did the bleeding for me. Quite a bit of fluid in the catch container (probably equal to pumping the brake pedal 10x). Fortunately the master cylinder level was still OK. I had bled the brakes several times on my '04 and there was never any power assist like this. Almost immediately after finishing and starting the car, the dash lit up with the 3 messages shown. I drove the car and the brakes were perfect, but the warning lights remained.
This morning I scanned codes:
C1241 - low or high power supply voltage
C1343 hydraulic system malfunction RR
I though for sure my brake actuator and/or pump were toast knowing that this is a fairly common catastrophic failure discussed on this forum and displays the same warnings. I reset the codes and just came back from a 10 mile drive with plenty of stops and no codes came back. I should add that my battery is less than a year old and kept on a tender.
I'm hoping I averted something major.

 

Brake bleeding requires Techstream to put the brake system in maintenance mode and open necessary valves. Refill the system, do a proper bleeding and try resetting the code. You might have to reset the codes before bleeding.

 

Another one lol

 

Anfanger, thank you. Your posts are always helpful. Guess I didn't do enough reading on the differences between my '04 and the '14. If no codes return, I may leave it alone. I fully bled all 4 sides with no air bubbles and the brakes are amazingly responsive and tight. I do own a scantool (not Techstream) that can do a full brake bleed including ABS on the car, so that is what I'll use next time.

 

If the VSC system doesn't beep at you angrily during the bleed, you didn't do it quite right. Or maybe it isn't supposed to beep when you depress the brake pedal with the valve open...? Either way, pro tip: hook up a battery charger when doing this, the brake actuator takes big amps when running and will drain a battery fast. Mine died during the procedure and the VSC ecu refused to talk to techstream afterwards. I had to disconnect the battery and run the bleed utility multiple times before I got it talking again. Also keep the battery charger on at least 12 amps, that actuator uses big juice.