Tire wear trigger code lights?

if they were badly misworn, it is a possibility. iow, not matching each others rolling diameter.

if you need new tires, get new tires. you don't have to buy them from the dealer.

if you don't need new tires, and don't want to replace them yet, get the codes read by a competent shop.

 

I think you should find a different dealer.
Doesn't sound to me like they have a good handle on anything.......except extracting money from your bank account.

So, NO, unless the tires are BADLY worn that story is bogus.
And you likely could get new tires somewhere else a lot cheaper......for the SAME tires.

 

I say no. There are sensor codes but they are specific to a problem with the sensor like failure, foreign object, etc. they are relatively expensive to change as they have to pull the sealed bearings which have the sensors inside them. Ask which specific codes were read. Always ask.

The egr cooling tube gets clogged up and is hard to clean so most mechanics will replace it. While in there (a big job) they could clean the egr valve. It is a good thing to do as many believe blown head gaskets can result. The problem is some service advisors are not good on translating what their mechanics told them.

 

If I were a mechanic before I followed that theory I'd find some wheels from another car and swap them in and see if the indications changed. In my time (since '12) following this forum I don't recall anyone reporting worn tires causing problems (beyond the obvious traction, handling, etc). On my v I changed tires because of age, not miles as I was running Michelins and not racking up huge miles per year.

 

I just would want better answers and better options.
If you need tires, you need tires, and probably should get them for that reason alone.
BUT...
Are they saying the codes are being triggered because the tires are worn? Or are they saying the codes are being triggered because the tires aren't holding air and PSI?
And even if you need tires, I wouldn't appreciate being pressured into purchase based on this only "might" solve the problem.

I just don't like the answer that the sensor might be bad, but let's try a set of new tires first.

Although whenever anyone says they need tires? My safety first blanket response is get new tires. So if they worn? And do need to be replaced regardless of warning lights and codes? It's not a bad idea to replace them.

 

Did the technician check the speed readings from all of the sensors, or just see that a diagnostic trouble code (DTC) for a speed sensor problem had been stored, notice that the tires were worn, and stop there?

When the car is moving, if one of the sensor readings is zero or very different from the others, it would tend to rule out uneven tire wear or inflation as the cause, of course. For most brake system DTCs, the speed sensor readings at the time of the malfunction should be in the stored freeze frame data. If these haven’t been cleared, they can be retrieved using a Toyota Techstream diagnostic system, which also has a Data List feature that can show the real-time sensor readings as the car is driven, or as a wheel is turned with the car on a lift.

An INF (information) code should also have been stored, identifying a specific problem, such as a difference in reading between two wheels, a zero reading, or a power supply problem. Some of these might also rule out a problem with the tires. See the procedures for DTCs C1464 or C1466 in the Repair Manual (more info).

 

Priyuschat admins are doing their new members a disservice by not automatically setting notifications when someone signs up. As a result many of us that try to help are often talking to the wind.

In any case, I may be a bearer of bad news in that your updated symptoms sound like the dreaded brake booster and actuator problem. Hopefully I am wrong. Prius is 99% brake by wire except for a total failure of those two parts. The booster creates hydraulic pressure with an electric (buzzing) pump and stores it in a hydraulic accumulator. The brake actuator is a combination master cylinder, brake ecu, traction control and abs module. The brake ecu is on the network and helps to determine if hydraulic braking is needed or if regeneration of electrical power is sufficient to slow the vehicle. It is also controlling traction control and abs. So a common problem is the booster starts to fail causing it to run for longer and longer times creating the pump buzzing sound. It is located near the actuator on the drivers side engine firewall conveniently tucked under the windshield wiper assembly. On mine the booster would run every 15 seconds or so to maintain brake hydraulic pressure. It will also run when you first open the driver's door after it has been sitting for a few hours. It will be louder as you are still outside of the car and can hear it more directly. The booster has a sealed nitrogen chamber separated from the brake fluid by a flexible metal diaphragm, something like a water well pressure tank. The metal diaphragm starts leaking and nitrogen gets into the brake actuator (master cylinder/ecu/abs) and causes it to fail as well. The booster is running a lot but you just don't hear it at speed because of other noises.

Now the bad part. Sometimes they won't throw a code or even cause the ABS/Traction Control lights (especially after a code reset) because it takes about five minutes of continuous running to trip a specific code. Sometimes a complete Techstream algorithm brake flush (to get into all the actuator passages) will make the problem go away for a day or so.

Now for the sad part. Dealers and Prius mechanics know this is a chronic problem especially in high mileage cars. They have replaced hundreds of these per mechanic. Toyota has a free replacement program for most Gen 3 Prius systems EXCEPT for the Prius v. At first they would replace only the booster but soon found they usually needed to replace the actuator as well. The job takes many hours because of access. For Prius v owners, its used or new repairs at our expense. It has a book price of around $4k at most dealers, I was quoted $2250 at my dealer. They are a hard pair of parts to get to especially on a v. I had an independent Prius mechanic change mine with used for $1200 and he warranted it for a year. Works good now.

Yes there is a failsafe mode should the accumulator or actuator fail 100%. A pair of normally closed solenoids in the actuator fail closed and your brake petal gets real hard to push as you are now operating the brakes directly with no power brakes.

From Toyota with the brake actuator/ecu shown on top:

 

Likely won't have any impact on your buzz but..............
At 7 years old, if it has the original 12 V battery, it likely is due to be changed out.
With all of the computer systems onboard, when ANY trouble shows up you need to FIRST be sure that the power supply is healthy.

 

if the battery cooling fan is more noticeable than in the past, unless you just got hearing aids (like me) that is not fine.
i would start by cleaning it. and yes, these are great cars until something goes wrong, then you need deep pockets, and a membership at your dealers yacht club...

 

'not being driven much'. definitely test the 12v as sam mentions above.

 

I could tell you to not worry about it and but its better to be safe than sorry, knowledge is power. When the ABS and Traction Control lights come on with no codes its likely the booster. Its a known weak point on gen 3s just like oil burning and clogged egrs. We are assuming the ABS and Traction lights came up with no codes or the dealer would have been positive about a wheel sensor. The abs wheel sensors throw specific codes. Its not a bad idea to replace bad tires as they can get you into as much trouble as bad brakes. The brake booster problem is usually progressive, it still works for a variable length of time. When you get hard brakes it probably has lit up your dash several times. Here is what you do. Listen for the booster pump as you open the door with the key for the first time in the morning sometime. Listen for what it sounds like. Then get in the car with the windows closed and start it with the air and radio off. Press on the brake and hold it several times until the brake booster comes on. Now you know what it sounds like. Then listen for it repeating frequently.

 

Interesting thread.
If I was a betting man, I would say the tires are not the issue...if currently these tires are the same brand and model and wear is not abnormal.

But, even the OP writes the tires are worn.
Without seeing how they are worn, I for one can not say the tires need replacing.. but the OP seems to imply the tires do need replacing.
That implication matches the dealers opinion.

My two cent comment at this moment is to read (and list for us) the codes that are setting the dash light...that will be a lead.
OP could remove the rims from the v and look for a chaffed or damaged wire and even go further by cleaning/removing any brake dust from the sensor areas.
Might be best to replace the tires, rule out that possibility, see if the codes continue and revisit the dealer or a different dealer/ mechanic.

Good luck.

 

is it the original 12v?

 

Well one bad sensor might not cause all those lights but..............
One bad 12 V battery definitely CAN.
If it is 7 years old, it NEEDS to be replaced.
The next time it gets low there might be even MORE lights that come on.