I did brakes on an 04 BMW 745li front pads, rotors, rear pads, rotors, front and rear sensors. A lot of fluid spilt out of the cap because someone put fluid in the res when the fluid got low So after I complete all the work, i check the fluid level and it is good I then go to back the car out and every brake light on the dash lights up and the pedal is fading. I pull it back in, bleed the brakes, fill the res and everything is fine. Im not a BMW expert but I don‘t understand why it would do that any solutions?
The brake pedal would be mushy to say the least after a brake job. So after servicing, the brake pedals should be pumped to make the brake pads go to its proper position at or very near the rotors. Then you can check the fluid level and correct it. Of course to turn off the check brake pad lights you have to turn on the key without starting the engine and wait for approximately 30 seconds. But frankly I do not understand why your brakelights turned on or why you even needed to do bleeding assuming that your braking system was good before you started the servicing and that you did it properly. I can only guess that since you did not pump the pedals immediately after servicing and proceeded to drive the car then the abs/dsc system noticed low brake fluid pressure and triggered the checklights. Additional info (food for thought): checklights - displays on cluster based on lamp control module instructions (in turn based on sensor inputs) brakelights - turns on when pedal trips pedal sensor or when lcm finds high circuit resistance e-brakes - turns on based on position sensor on brake lever brake fluid level- turns on when level is below minimum in reservoir abs/dsc - turns on when low pressure is detected in abs pump along with many other possible causes
