In March, shortly after disengaging Cruise Control, I applied my brakes as I approached a stoplight and the pedal was harder than usual. Thinking nothing of it, I continued driving, but acceleration as the light turned green was sluggish. Next stop light, the same problem. As I approached my turn, I heard squealing, smelled burning, and by the time I was on the next road, smoke was pouring out the front tires. Luckily, I was close to the dealer who has taken good care of us in the past, they replaced master cylinder, front pads, and charged me a lot for labor.

Here we are 3 months on, and the exact same events happened, but I was at the other end of town and closer to a mechanic we’ve not ever used before. He’s informing me it’s a failure of the ABS. The dealer says no way that’d happen without the dummy light coming on – yet he concedes anything’s possible. My concern is spending almost exactly the same amount of money for a new ABS pump (the new diagnosis) and having the same problem in another 3 mos.

Two questions: Is the newest diagnosis fairly solid (everybody admits that there are no guarantees)? And the 2nd question is, could this be related to my cruise control somehow?

No, I do not believe the diagnosis is solid. ABS functions by interefering with the brak lines hydraulics, interfering with the ability of the line to stop the wheel. It’s either engaged and interfereing or not engaged and allowing the wheel to be stopped. I see no way it can cause brakes to lock. Others may offer differing advice, and I’m open to theories.

I also do not see any way this could be related to cruise control. Cruise control only moves the accelerator linkage (or sends an acceleration signal to the ECU, depending on if you have wireless acceleration). It has zero interface with the brakes.

Are you sure hey did not replace the brake calipers?

Possible causes of stuck calipers are

  1. the calipers themselves (high probability)
  2. collapsed brake line innards (medium probability, but very possible condidering that the fluid’s been overheated)
  3. master cylinder (since it’s been changed, it’s not in question at this time)
  4. vacuum booster, sticking rod (very low probability, but not impossible).

If it were me, I’d change the calipers, pads, rotors, and front lines, flush the system and refill with fresh fluid, and make sure the booster seems to be working properly. I’d also inspecxt the linkages at the pedal end to be sure nothing is hanging up.

In this case, I would get the car towed back to the dealer. If something that was done three months ago is still under warranty, then it would be repaired free.

As you stated, there appears to be some disagreement on the ABS pump diagnosis, so unless this second mechanic will give you a full refund on the repair if it is not the problem, I would stick with the original mechanic/shop.