What are the symptoms of an ABS actuator malfunction, and how frequent is it?
I have an intermittent soft brake pedal that occurred 8 times in the last 2 weeks / 500 miles that my trustworthy non-dealer Lexus master tech says is either due to the master cylinder ($500 P&L) or the ABS actuator ($2300). He doesn't know which one it is for sure, but suspects it's the actuator having seen this presentation before. I'm trying to decide whether I replace the cheaper master cylinder first or go the more expensive route, which is why I bring the question to y'all.
Half of the times it has occurred I have been exiting a freeway, pressing the brake pedal to slow down only to find that it goes to the floor. I can stop the vehicle, but have to push harder than I would when it works normally. If I pump the pedal, the brakes work normally after the 3rd or 4th pump. The brake fluid is clean and full, the hoses are intact - no leaks. Brake pads are new (<15K highway mi). There are no noises. The Tech's inspection revealed no unusual findings.
2009 Tundra CMax 4WD 142Kmi
Bilstein 5100s set at +2.5in lift at 100K mi