Brake, ABS, Traction, ((!)) lights intermittent after brake change, driving thru snow w/ loose wheel

Hi all,

2010 Prius II with 83k miles

I changed my brake pads and rotors (all four wheels) earlier in the week (my first time doing that -- a good learning experience) due to very rusty front rotors failing annual (but very late) safety inspection. I finished the last wheel (front left) on Wednesday before snow came and all seemed fine with a little local driving.

On Thursday we drove through some deepish slushy snow that knocked the center under engine splash shield loose at the rear so it was dragging. Saturday morning before driving again I removed it (unscrewed the bolts) before driving again. This time, I heard a soft thumping from the front left that stopped when braking. I looked at the wheel from the exterior and saw nothing odd, so continued on and then home. On the way home the sound got worse, and then traction control, brake, ABS, and ((!)) lights came on. At home I realized that wheel was loose (all lug nuts could be loosened by finger, and some had worked themselves out several rotations) with a light semicircular gouge on the new rotor. It's very possible that in forgetful haste I didn't fully tighten the lug nuts after lowering the car on Wednesday (oops!).

I removed the wheel and checked everything out (it looked fine from what amateur me could tell, other than the gouge). On replacing the wheel, one lug stud pushed in, so I had to remove the caliper and caliper bracket, reseat the lug stud, and reassemble. The lights we still on after restoring 12V and restarting a few times. I tried but failed to get my cheapo MVCI cable to work (first time trying in several years), so took it for a local drive and midway through the lights cleared.

I was happy (other than the gouge). But then went out later and the lights came on again while driving. But then they went out on their own.

Any thoughts on what may be going on? Dirty ABS sensor maybe? Will there be codes I should try to read (or go to AutoZone and see if they can do that for me) even if the lights aren't on any longer? Are useful codes available via a jumper/flashing method?

Thanks!

 

Thanks. I'll take a look at the sensor cable and harness -- probably next chance is Thursday. I'll also see if I can get my MVCI cable and Techstream working to look for any codes.

"Gouge" may have been overdoing it -- it's an abrasion a fraction of a mm deep and maybe 8 mm wide. It's in far better shape than the rusted rotor I took out. I'll get a photo of it -- and I'd just as soon replace it with a new one than ask a local place to look at it (as they'll likely "offer" to replace it for $200-400). I do need to have two warranty items done so will get them to look at it then.

 

More information: noticed during a test drive, after the lights came back on midway, that the Energy Monitor shows power from battery to wheel (and engine to wheel if the engine is running) when stopped in Park or B, regardless of how hard I press the brake pedal.

The lights haven't gone out yet for me to see if this occurs when they aren't lit.

Does that support it being an ABS sensor issue?

Also not mentioned: the front brake dust shields are horribly rusted, with portions crumbling away. So it's very possible the window for the speed sensor is crumbling at the edges. Will investigate when the sun comes out a little. And try to read some codes...

Also I did use a torque wrench on all but the wheel lug nuts (don't have a 21mm socket -- will remedy soon that to prevent any future loose wheels!).