One month before I had issue with my ABS brakes. Now four lights are on includes Traction & brakes. Before that I noticed fluid whistling sound while pressing brake at stop position. Brake fluid is also less from low level position. After having fluid to upper level, some times these lights disappears. When it disappears the abs works as normal, but the whistling sound again comes on pressing brake at stop position. I want to know the possible cause of problem. Is it some brake fluid service or anything else..
The C1391 is a report of pressure leakage, so leakage has been observed, just not by you. The leakage can be (and often is) internal, so no brake fluid ever leaves the car, just finds its way back to the reservoir. In a Gen 3, there are two different assemblies where such leakage could be happening: either the "booster assembly with master cylinder (includes actuator)", or the "pump assembly, brake booster" (also known as the accumulator). Neither one is a picnic to replace, so if you have a way (if it's leaking fast enough, a mechanic's stethoscope might work) to determine which assembly you need, that could save some time and money.
Found this salted away, a custom instruction for replacement of the lower component. The earlier instruction, in the Repair Manual, says to remove the full lower rear support beam, and I guess the dealership mechanics revolted.
