Piston Slap: Tranny Tribulations Turned Tiller Trouble?

Sajeev Mehta
by Sajeev Mehta
piston slap tranny tribulations turned tiller trouble
Mark writes:

In my 2016 Miata, the electric power assist for the steering has died but the fuse for it is fine. It was working fine when it was towed to a dealership to have the manual transmission rebuilt and it was dead when I picked it up. Any ideas?

Sajeev answers:

First, let’s mention that ND Miata transmission replacements are a thing. Wow.

Gearbox removal is no cakewalk, but this long video suggests there’s no need to muck with the electric power steering system. So either the dealership addresses the issue or maybe, possibly, the system woke itself up after a few driving cycles?

Once again, no matter the existence of a valid diagnostic tree for electric power steering systems, the joy of owning a car under warranty means this isn’t your problem!

One thing I’ve learned in my years working in auto retail is mistakes are nearly impossible to avoid: too many moving parts (so to speak) are in play, which is the nature of this business. So mistakes shall happen, but will they resolve the problem to your satisfaction?

[Image: Mazda]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

Join the conversation
5 of 13 comments
  • Jean-Pierre Sarti Jean-Pierre Sarti on Apr 05, 2019

    I've learned the hard way that fuses can look good but are bad. I would change the fuse and get a fuse tester as a my first step.

  • MBella MBella on Apr 05, 2019

    First, just take it back. They'll fix it for you. I suspect they left a ground strap loose when doing the transmission. Those racks use a decent amount of current, and a loose or missing ground strap can keep them from working properly.

  • Bumpy ii Bumpy ii on Apr 05, 2019

    Random guess: a sensor on or near the steering rack was disconnected and not plugged back in.

  • Sgeffe Sgeffe on Apr 05, 2019

    Surprised that the OP could even turn the wheel, as from what I understand, when an EPS system is on the fritz, it’s damn near impossible to turn the wheel, versus when a hydraulic system goes Tango-Uniform! I probably would have sensed that something was amiss before I left the parking lot of the shop. Of course, this is a Miata, so there may not be a need for much, if any, assist.