ABS failure

ABS failure

I was recently driving my model S, going back home from work. I was driving on a three lane winding road with a relatively deep incline and going at about 55 miles/h. All of the sudden the car seemed to speed up and got a message on the dashboard indicating that the ABS was inactive. When I tried to slow down the brake pedal would not responde and was very hard. Fortunately it was pass the rush hour and traffic was light. No accidents.
Scary situation. Dissapointed that an essential part of the car would fail without absolutely any warning.

JstACarGuy | January 10, 2014

I hope you called service immediately and had the car towed. Sounds more like brake failure.

Andre-nl | January 10, 2014

"fail without absolutely any warning."

Would you expect a message on screen saying: "Brakes are about to fail in 10 s?" ;)

Did you lose the brakes all together or just the brake assistance?

Roamer@AZ USA | January 10, 2014

You got a message that the ABS was not functioning. I would call that a warning. ABS is a recent feature added to cars. We drove them for 80 years without ABS.

Glad you were safe.

Andre-nl | January 10, 2014

Roamer, I think that from the description of the behaviour, he lost more than just ABS.

Roamer@AZ USA | January 10, 2014

@Andre, It read to me like he lost power assist and ABS. The car went old school hydro mechanical. I can understand it would be concerning to lose all the power boost and control enhancements and be left with only the standard hydro mechanical brakes. But the car still has full brake capability it's just that the driver has to apply and control it manually with out power boost and technology helping.

Power brakes have been around so long that most drivers have no idea what manual brakes feel like. Also boost designed brakes are even harder to operate manually than the old all manual hydro systems.

Big T | January 10, 2014

I lost power assist brakes and power steering once in an ICE car in heavy traffic. Fortunately, I had driven cars from the days before those were standard so I knew I could control the car using more muscle and did not panic. Seems like Roamer is right. We have a generation of drivers that have never driven cars without all the automatic and power assist functions. They don't know the old school way of driving.

Andre-nl | January 10, 2014

Roamer, yeah, that was exactly what I was trying to say, that he lost power assist in addition to ABS. To me it seemed you thought he only lost ABS. It seems he didn't lose the brakes.

Big T

How big/heavy was that car? It's not just the drivers, it's also the cars that keep getting bigger and heavier.

Big T | January 10, 2014

Andre-nl, it was a boat from the era of big sedans. It was my Dad's Olds 98.

Nu2Ecar | January 10, 2014

Big T, Designers have built in less mechanical advantage as power-assist has become standard. I bet your Dad's Olds was easier to stop than a Tesla, or most modern cars, when the power-assist fails.

Big T | January 10, 2014

Nu2Ecar, not sure. This was the last of 3 98's that he owned. This one was the final model from the mid 90's before Olds was discontinued. It had modern features like ABS and traction control. Even at the end it was big at 205.7" x 74.6".

info | January 10, 2014

Eduardoa@austin. You might want to check out "Sticky" post. This issued seems to need a "private" designation.

Dramsey | January 10, 2014

Big T, just curious: power steering systems of that era used hydraulic assist via a belt-driven pump. Power brakes used intake manifold vacuum. It seems unlikely that both would fail at once unless the engine stopped...

Big T | January 10, 2014

Dramsey, yes. Started with the alternator and subsequently lost everything. I was traveling downhill and put the car in neutral. I had to cross several lanes of highway traffic while controlling my speed with a combination of braking to slow down and gravity to slowly speed up until I got past a stretch of guard rails meant to keep you from hurtling down the mountainside. Then I could finally pull over.

Epley | January 10, 2014


This happened to me when the bearing on one of my front wheels failed. The car needs service. Call the rangers.

Also, please make this thread private (for owners only)


howardhhchu | January 12, 2015

I have same problem. Called Tesla today and they towed the car away.
Very upset as I just got the car for a week!!

TSLAholic | January 12, 2015

@Roamer@AZ USA

"we drove them for 80 years"

Let's see... 80 plus 44 is... yup, you've been driving for a minimum of 124 years! At what point does age begin to overshadow driving experience? :)

mathwhiz | January 12, 2015

Don't forget the emergency brake (if needed) is on the steering column. Each time you press it (Park) the emergency brake is applied, although I've never had call to test it...

mathwhiz | January 12, 2015

Of course, not sure how they are affected in @Eduardoa's situation...

tc4542 | January 12, 2015

Just a scary thought... But you have to wonder if this might have happened to the guy who went over the cliff the other day. I've been thinking about this for a while but haven't posted until I saw this.... Wow...

Boukman | January 12, 2015

Glad to hear you are safe man... I would be quite interested to hear Tesla's explanation for the ABS failure...Please keep us posted. Good luck

FelixMendeldog | January 13, 2015

Since there’s no engine vacuum to bleed off for ‘free’ brake boost as is used in most ICE-mobiles, Model S has an electrically powered booster for the foot brake. (Some ICE cars use electric boosters now too.) The antilock subsystem depends on the booster system to quickly modulate the brakes when wheel lock-up is detected. Clearly, some part of the booster system failed, leaving Eduardoa with un-boosted brakes.

Though alarming, this sort of failure isusually not incredibly dangerous. Since the brakes are hydraulic (and this is not the description a hydraulic breach) they work; they just get much more difficult to press—put both feet on the pedal and give it hell. I certainly wouldn’t want the boost to fail just before or during a panic stop situation as stopping distances are longer with unassisted legs. (Yes, this happened to me a couple times.) But if you ever press the brake pedal and it goes soft all the way down, get on the parking brake at once! Though extremely rare, that’s what it feels like when a hydraulic system fails. If that ever happens to you, it’s likely someone is trying to make your death look like an accident ;-)

@mathwhiz is correct: pushing “Park” on the stalk actuates the smaller rear calipers (driver’s side rear wheel at the 11 o’clock position, passenger side, 1 o’clock) for parking and emergency stopping. These ‘extra’ brakes are on a separate circuit as required by law/common sense.

Haggy | January 13, 2015

There's a fair amount of information out there on the iBooster for anybody who wants to read it.

I know what it's like to stop a car without a booster, primarily because cars used to be made without boosters. Back then they were also made without split master cylinders, so if there was a hydraulic leak, the pedal went to the ground and the car didn't stop. I had that happen to me. These days, a leak on one side means impaired braking rather than a complete failure. It's far less scary. I once had a car with a slow leak, and it took me a long time to get around to rebuilding the master cylinder. In the mean time I kept topping off the brake fluid. In theory I shouldn't have been doing that since a partly used bottle could get moisture in the fluid and make things worse. But I survived.

I don't know when brake boosters became standard, but even in the mid 1970s I still saw cars advertised with power windows, power steering and power brakes. So there must have been some without them.

Opafiets | January 13, 2015

Didn't the guy who does the videos with his kid in the back seat have an ABS failure?

johncrab | January 13, 2015

As they taught us in Driver's Ed, if the brake booster fails, you still have brakes but you have to push a lot harder. On a Prius, this does not hold true and that's the one eerie thing that has always bugged me about that design.

Don't we all wish we could hear, "I've just picked up a fault in the AE-35 unit"?

Haggy | January 13, 2015

When I took driver's ed., GM was into making driving as easy as possible with all those new fangled technologies. It wouldn't quite be true to say I could have turned the steering wheel or pushed down the brake pedal with a feather, but it wouldn't have been far off the mark. These days, the idea is to "feel the road" and there's more than enough feel to feel in control but not enough to make things a struggle. I don't think anybody is likely not to figure out to just press harder.

johncrab | January 13, 2015

@ Haggy - I know of what you speak! GM's over-boosted steering from the 70's was so extreme that while parked with one finger, one could spin the steering wheel lock to lock and back. Zero road feel. Spooky. Brakes then gave many Driver's Ed road instructors whiplash. It was the way of things.