Traction control kicking in when turning right
 

Hi all,

New to the forums here, and a new owner of a used 2015 BRZ. Pretty much since the first day of collecting the car, I've been experiencing the traction control kicking in (light coming on + sound + vibration) when turning right, even at low speeds (50km/h).

I would say the traction control issue is a symptom, not a cause. Something is causing my rear wheel(s) to lose grip and thus triggering the nannies. Also, sometimes after making a right turn, I can feel the car pulling to the left.

All of this is only happening when I make right turns. Left turns are perfectly fine.

My car is on used stock 86 absorbers and Continental MC6 tyres.

It's been two months. I've sent my car to multiple workshops (Subaru authorized workshop, an external suspension specialist, a tyre expert shop), and nobody can solve the mystery. I have tested with two different stock 86 absorbers. I have rotated my tyres. I have checked the alignment. The wheel sensors are working fine.

I'm at my wits' end. Please help!

so to clarify, all 4 tires are the same age, same wear, and same type? i believe you're indicating this, but want to make sure--there's been a number of cases where people attempt to put higher-wear tires on the front, new tires on the rear, and the difference in tread depth is enough to trigger the system.

when was the last time the car was aligned? do you have a printout of the alignment specs? if the tires are the same all around, the only few other options are going to be the steering angle sensor in the steering wheel, alignment, wheel bearings, or worn bushings in the rear a-arm setup.

Yes please verify wear level/size of all tires first.

Thanks for the responses.

Yes, the tyres (225/45r17) have the same age and wear - about 2.5 years old now I think. Rotated the tyres in Feb, didn't make a difference.

The last alignment was done a month ago. I do not have the printout unfortunately. Got the wheel bearings checked last week and they looked fine.

I can get the workshop to look into the steering angle sensor and bushings.

i really think the problem is going to be in the rear sub frame bushings. there's a number of them back there between them solid car chassis and the wheel assembly, and if some are loose, alignment specs can read correct, but when the car is subjected to loads(acceleration/deceleration/turning), the bushings can be loose enough to alter the alignment significantly and cause the issues you're experiencing.

for wheel bearings to alter alignment, they usually fail significantly enough to make some horrible noises. same with the steering angle sensor-- it's possible, but unlikely. there'd be more symptoms of that as well than just right-hand turns.

i really think the problem is going to be in the rear sub frame bushings. there's a number of them back there between them solid car chassis and the wheel assembly, and if some are loose, alignment specs can read correct, but when the car is subjected to loads(acceleration/deceleration/turning), the bushings can be loose enough to alter the alignment significantly and cause the issues you're experiencing.

for wheel bearings to alter alignment, they usually fail significantly enough to make some horrible noises. same with the steering angle sensor-- it's possible, but unlikely. there'd be more symptoms of that as well than just right-hand turns.

^^^ +2 ;) Not wheel bearings.


Worn bushings, or damaged suspension components. In any case, system initialization after any change is key.

Why would a wheel bearing not do this?

The air gap between the tone wheel and sensor is critical, a loose wheel bearing will alter that air gap, and it's a Subaru, the rear wheel bearings are shit anyway.

At least jack the car up and check for play in bearings, steering and suspension components before theorizing about it for days. That's literally step 2, step 1 has already been brought up: check tire sizes and pressures.

i'm just a hackjob with an internet connection.

It would not do it because, as soundman correctly pointed out, for there to develop that much play, the bearing would be making so much noise that one would have to be a complete dipshit, or stone-cold deaf to not know something was seriously wrong.


The functional range for the sensor is way larger.

So you say, but I've seen some very small radial play influence track control and abs, and though much more rare, I have seen some major bearing play that was still quiet.

I get what you're saying and understand that it's an easy check, but I wouldn't take that bet.


This'll be interesting. Looking up recipes for crow now. ;)


edit: Doh! forgot that OP already checked them. Oh well... I guess big picture, yeah. Also, hard experience trumps all. On which platform have you seen it happen?

Let’s assume that the Torsen differential is not contributing to the problem. What happens when you turn off the traction and stability control? I would first look at the wheel speed sensors and/or associated wiring for defects. Have you or anyone else checked for diagnostic codes? I’m not certain about the Subaru, but some faults will only register a preliminary fault code and then when a certain number of faults are registered in a period of time then it will trigger a MIL code and the light will come on. I have seen chronic problems that escaped the check engine light coming on. Making right hand turns will cause the left and right and front and rear wheels turn at different speeds. If a wheel is erroneously read for speed, the system will correct for it. One time a friend’s pickup had a code show up for a bad camshaft position sensor and a bad wheel speed sensor almost simultaneously. Talk about a “WTF” moment. The left rear wheel would lock up while making turns. We thought at first it was a repeat of when a mechanic mistakenly added a viscosity enhancer to the differential. That version of limited slip differential did not require additives. A week later, a buddy’s’ 98 Lexus simultaneously developed a manifold leak and a bad O2 sensor. Completely unrelated problems can steer your focus away from fixing each separately.

Pretty much anything, I'll get cars and trucks that get undesired ABS or track control activation either when coming to a stop, setting off or turning a corner, check 'em out and there's a bit of play in a bearing, a bit of rust on a tone wheel, a bit of rust under a wheel speed sensor pushing it out 1mm.

I remember a damn lexus RX330 that had the right front wheel speed sensor coding for tone wheel performance because it was getting pushed up by rust. Of course the sensor broke in the knuckle, drill it out, roloc the mounting surface, grease it up reaaaaal good and slap a new sensor on it... Now that wheel was fine and not throwing a code, but the entire truck was now getting unwanted abs activation/no codes on the other 3 wheels because they also had a bit of rust under them. FML y'a know right.

These little shits are sensitive. The ol' classic are the older Ford Escapes, rust grows in between the front CV shafts and tone wheel and it cracks, so one tooth has like a .5mm spacing difference, and yes, that's enough to make the abs kick in.

Of course, I say subaru rear bearings suck because it's not abnormal to get an impreza/xv/outback/forester in with 2 destroyed rear wheel bearings, it's not even a surprise anymore.

So with the traction and stability control turned off, the car still loses grip on its rear left when I make a right turn at low speed. Same exact thing.

About the wheel speed sensors, Subaru ran diagnostics on my car two weeks back and found that the two front sensors weren't working (no reading at all). So they have replaced them with two new sensors, which are working well now. Everything else looked fine system-wise, according to Subaru.

I'm guessing it's more likely a mechanical problem than electronics then?

Again, I appreciate everyone's input and thoughts!

Diagnosing something like this from a distance is a challenge. One thing that I notice with the Torsen LSD on the BRZ/86 is that it is pretty aggressive. It feels like it treats even the slightest difference in rotational speed as a loss of traction. If what I understand so far is this: only on right hand turns the problem occurs, left turns are OK. Rear drive train components appear to be sound. When you say the left rear wheel loses grip, you mean it spins up trying to burn rubber? Or, does do you feel any wheel hopping; that is the wheel is more in sync with the right wheel and it drags and hops. If you found an open space where you can drive in tight circles left and right, what do you experience? You can try this at faster speeds, but don't get into trouble. Getting both rear wheels in the air, you can try turning each wheel one at a time forward and reverse with the driveshaft locked. Feel for any differences in movement. Note the direction of wheel spin on the opposite side if any. Next, with the drive shaft free to turn, turn the wheels manually again. If the opposite wheel turns, have someone restrain it and note any movement in the drive shaft. Any limited slip differential will behave differently from an open differential. There are many types of LSD and the Torsen is just one of them. Differential failures are not the most common thing at low mileage. In my experience, the most common failure is a pinion bearing, often accompanying the failure of the rear drive shaft u-joint. One time I had a differential that lost a ring gear bolt that floated around in the housing. The first thing it did was get in the spider gears and mess with the differential action. After it did damage there and fell out into the case, everything seemed to be ok for about a week or so until at high speed on the highway, the bolt got swept up in the oil flow and wedged between the ring gear and the differential housing casting blowing a gaping hole in it. Sounded like a gun shot. Layers of plastic bags and tape got it back to the garage. I once loaned out a car and later discovered that it had taken a turn too tight and the right rear wheel hopped a curb. It was later that week at 2AM and 10 degrees F I was stopped at a light. When the light changed I let out the clutch and BANG! The engine raced as if I was in neutral. The short drive shaft had broken right at the spline where is goes into the carrier. It was an easy fix since it was independent rear suspension and I could replace the right shaft without having to remove the differential from the frame. That did not change the fact that I was royally pissed at my buddy. Don't loan your car out to a Hoon. Has this car seen some serious drifting?

My suspecting the differential is sort of grabbing at straws. My two BRZ cars are the only Torsen diffs that I have any experience with and I have never had one apart on the work bench. I have read up and watched videos a dozen times and I can't completely grasp why it works the way it does. It is one of those things that I would have to take apart to see. When the car is driving straight, equal amounts of torque are applied to each wheel. There is a threshold where the tire loses traction and it slips. There is a certain amount of torque bias that the differential will allow and then it starts locking (or not). If something is whacked internally, could left wheel or right wheel bias be different accounting for only right turns affected?

I have sympathy for the mechanics who can't figure this out. When I twisted wrenches for money, I always got the stuff no one else could figure out or knew before hand that they would loose their lunch money on the job. I would tell the boss to take me off flat rate hours for the job and pay me hourly. I have found stuff that came out of the factory that because you assume they did it 'right' you would not think to go down that road. Some highlights are clutch disks installed backwards at the factory, overhead camshafts installed with the valve timing retarded and a crankshaft that did not have oil passages drilled from the mains to the connecting rod journals. The crowning jewel was when I got into a shouting match with the factory man from Rolls Royce after I repaired the charging system and I told him that it was an easy fix pointing to an MG-B in the next stall: They are all the same, there is the front, there is the back, it has four wheels and a motor... what else is there to know? Well, the one mechanic who was certified was on 'Holiday' and I was the only one that was not scared shitless to touch the Rolls. I did borrow the car for the weekend for a quality control road test. Lovely automobile, so I can sort of understand why the factory guy got huffy. That does not change the fact that he was a butthole.

I just have to know what is up with this BRZ. Probably nothing I thought of.

Check tire pressure, then have alignment checked. It was done a month ago, something not torqued properly could have slipped. I'd also check the speed sensors as mentioned, not too hard to knock one and damage it, they are just held in with a single 10mm.

I'd be surprised if a wheel bearing caused this. I have killed a number of them with no behaviour like this. Doesn't rule it out though.

RZNT4R reminded me of how spoiled we are with with our non-corrosive winters. I grew up just across the lake from Toronto and, while we didn't have wheel speed sensors, I can easily picture the failures he describes.

https://www.carcarehacks.com/wp-cont...sted-Frame.jpg

my money is still on either alignment or bushings. a right-hand-locking-diff could be a factory mechanical defect, but low likelihood

Mine is too, but I've come to see the wisdom of considering the sensor in the big picture.

I forget we don't have to deal with the scourge of vehicles in the northern climates.

Ha ha ha ha. Memories. Seems like all of my old British cars had stuff falling off. A door falling off onto the sidewalk is no way to impress a girl on a first date. So many rust stories, but one that is classic: I was driving my Austin Mini westbound on I-80 in New Jersey when I noticed the dash lights blinking and the ammeter going nuts. Checking the mirrors and preparing to drive off to the shoulder, I saw in the rear view mirror a trail of liquid and black stuff. The battery box sits in the floor of the “Boot” and the bottom rusted out causing the battery to fall through and drag by the cables on the ground. The bottom of the battery wore down exposing the plates and draining the acid. Since the engine was easy to start by pushing the car and it had a generator, I drove home and stole a battery out of my Triumph so I could do my pizza delivery that night. Helps to have a buddy with a welding torch. Rust happens.

I remember when my dad was bench-testing a generator, he showed me how it wouldn't work unless it was fed some initial current through the field coil. I learned the need for some battery even when bump starting. At least that's how it was on 6-Volt VWs.

Correct, unless the generator is a magneto. I pulled the battery up through the floor, wrapped it in an old rubberized tarp. The battery despite its condition, still had enough power to light the idiot light, but not the starter. One person alone could push start a Mini and if nimble enough, jump in the car and not get run over. You can skate board the car with you right toe on the clutch or get the car rolling and jump in. Mine barely tipped 1,300 lbs. More than a couple of times I would find it parked on the sidewalk courtesy of a random football squad fueled by alcohol.

Ah, that helps me. I guess the cell will work as long as it's still wet. I've bump-started every car I've owned, including the frs, but I'm a pretty big guy. I only bumped the frs to prove to myself that I could do it.

i should probably try to do this some time.. the push-start part feels different to me though...

I don't remember if first gear was too short. It took me a couple whacks.

Hi everyone, I have an update... My traction control issue has been solved!

A workshop managed to find that the bolts on my control arm (located at the front) were loose for some reason. After tightening them, no more traction control kicking in at low speed at all!

What a relief. It has been 6 months of going from one workshop to another, which always ended with "Sorry, we couldn't find what's wrong." Everyone kept focusing on the rear (because the car's rear would slide pretty badly at right turns, thus triggering the traction control), but all along the source of the problem was with the front.

I hope my experience will help others in a similar situation next time.

It certainly will! Thanks!