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Discussion Starter · #1 ·
I don't think my ABS is working. On the freeway, if I apply really firm pressure the wheels lock up. This happened 4 times in emergency braking at speeds of 50 to 70 mph. I then got suspicious and have replicated this with no one around three more times. On city streets at 45 mph, the tires skid, I feel a single pulse (sometimes) and then it stops abruptly. Going over an intersection hump at 50 mph I tapped the brakes and felt a double pulse, but nothing more. Original brakes, which otherwise work perfectly. Just switched from summer tires to all seasons. No ABS lights are coming on, except briefly at start up. No codes either. All of my internet research and forum research for the last couple days I can't find anything like this...

However, I had this happen with my 04 Pontiac GTO 10 years ago ONCE, but was never able to replicate it. Before I take my car to the dealership, I am open to your ideas of what might be going on here.
 

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Now I might be the fool here. But I think skidding is an inevitable part of braking? Pretty sure I have never seen a car comes to an abrupt stop without skidding, or maybe I just never payed attention to it. What ABS does is allow steering to still occur, have you tried testing that?

I have noticed my 2015 almost never seems to utilize ABS. I was under the impression they had somehow removed the pulsing pedal sensation to make modern vheicles more user friendly.

Then just a week or two ago I was on some ice braking & sliding and sure enough the dodododododo kicks in.
 

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Nope, you should definitely feel the pulsing. Sounds like an issue to me.
But of course, you really need to be standing on the brake pedal, and if you get into a 4 wheel skid, your brakes are unsafe. Get them looked at.

MW
 

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I've slammed on plenty of ABS brakes, it's definitely an obvious feeling.
I'm really surprised you aren't getting an ABS light. Very interesting.
How many miles are on your car/what year is it?
 

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Discussion Starter · #5 ·
2015 with 20k miles. When it was new it and I tested it, it pulsed. As far as steering goes, I have to let off the brakes to steer. When the tires are skidding, it doesn't steer and the last time I tried it at speed I felt the rear wanting to come around. I'm not talking ABS lock-roll-lock-roll. I"m talking a full 4 wheel lock that doesn't release unless I take the pressure off the pedal. I'm thinking I need to take it to the dealer. As I recall, when ABS activates, the ABS light should also come on the dash momentarily. I am not seeing it activate during hard braking either.
 

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What tires are you running on?
What is the temp?
If summer tires, they are useless below 40*F.
 

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Discussion Starter · #8 ·
So I have scheduled a service at different dealership for Thanksgiving vacation. I will update this thread once I have a diagnosis.
 

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Discussion Starter · #9 ·
Update diagnosis: So I took the car into the dealership today. They returned it to me informing me that there is nothing wrong with the brakes. I'm going to skip the part of the story where I'm not satisfied with the dealer explanation, to avoid bias.

So I need to establish what is "normal" for ABS in our cars.

Help me by describing the following:
1. What does your ABS feels like when it activates?
2. At what speed?
3. Are there any lights that flash on the dash?

The more people that respond the better this works.
 

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Discussion Starter · #11 ·
The only time I've ever really noticed my ABS system coming on is slippery conditions. So in rain or snow. I auto x and can get the brakes to lockup all the time, not that I'm trying to. So I think your brake are working correctly. Maybe wait for a wet day and try on an unoccupied road.

Sent from another galaxy.
What does it feel like? In slippery conditions? Does it pulse, grind? Is it rapid feedback or very subtle?

Thanks, I found the part about Auto-X interesting.
 

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Discussion Starter · #13 ·
Update: Couple weeks ago on the freeway a guy tries to merge on top of me. I applied maximum braking force and swerved to the edge of my lane. I heard and felt tires skidding, as the rear began to come around on me. Input on the steering straightened everything out ok. Front wheels momentarily pulsed and I had full steering control during the event. But the rears came loose. Since the dealership is claiming it's fine and there are no CEL's, I'm trying to look at this through another perspective.

It's a light car, but front heavy.
The rear springs are stiffer than the fronts.
It comes with grippy summer tires, but I put all-seasons on it.
The rear brakes can help induce oversteer bias under the right conditions, for "tail-happiness."

I'm wondering if the design of the car, with the harder all-season tires, is to blame? And if it is, I doubt any Ford Dealership would acknowledge it. I never experienced this with the F1's mounted. It all started when I switched to the Dunlops HP signatures. I'm wondering if under maximum braking, the rear of the car lifts enough to allow the rears to lock, with 90% of the weight going to the front tires? I'm thinking Summer tires would hang on, but the all seasons just want to slide around.

I feel like I can't be the only person who had this experience.
 

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Yea that sounds like a plausible theory to me.

I have winter tires on mine and have had to slam the brakes a couple times and I remember ABS coming on and the pedal was definitely pulsating. Now I believe both times there was snow on the road so grip is obviously much different.

I'm totally speculating here and have no clue for sure so if someone knows otherwise please inform me! But maybe the PCM applies ABS differently at different speeds? When I've had it come on I wasn't doing more than probably 30mph. Maybe try going slower, ~25, and testing it out and see what happens.
 

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Discussion Starter · #15 ·
At slower speeds, under 50 mph ABS works fine, front and rear. The dealership tested it at 35 mph. Even in my most recent incident, the fronts never gave up control--I was steering with my foot in the brakes, but the rears were sliding and wanting to come around.
 

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This sounds totally normal to me, we all know this car is intentionally designed to oversteer (instead of the front sliding in a turn, the rear of the car comes out and the car rotates) and this oversteer can be assisted by either letting off the gas or pressing a little brake. You weren't turning per-say, but slamming on the brakes and turning the steering wheel even a little bit is enough to shift momentum and rotate the car, I'd say the lesser traction of the A/S tires definitely made this easier to happen, but it doesn't sound unordinary. This is exactly why I think driving this car too fast as someone who is inexperienced in an oversteering car is dangerous. I'd hate for my girlfriend to hit a turn too fast and hit the brakes in the middle of the turn out of panic. She'd spin right around and be in a ditch.
 

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Discussion Starter · #17 ·
So I like updating my modest little adventures...

So I went to the tire store to inquire on replacing the tires for something stickier (should have listened to brian60 last year when I was tire hunting...). So they offered me half credit on my tires, which is not unreasonable since I've put 5000 miles on these tires before deciding I had buyer's regret. But once again, I just don't have the money to jump up to MPSS. And I'm once bitten, twice shy, afraid to try a cheap summer tire. I didn't love the F1's, but I did trust them. So I did some reading on the topic of air pressure in the tires. Now this topic is a bit of black magic, so just because I got it right, read with caution as it may or may not work for you (unknown internet readers).

I put the rears at 36 psi, which is OEM recommended. Then I took the fronts down to 33 psi. The improvement is dramatic. Not perfect, but I can feel the ABS working strongly and the tail hardly steps out (if at all), even when emergency stopping from speeds above the posted limit... I'm still experimenting with the pressures to find the sweet spot, but this is my best set up so far. Soft up front seems to help balance the car out on the Dunlops.

It would seem that our cars are sensitive to the rubber we shoe them with, which is new to me. The F1's are grippy enough to induce understeer, which was causing me the undesired choppy feedback in cold weather hard cornering. The Dunlop HP A/S Signatures, however have enough slip that they encourage oversteer on concrete at freeway speeds (rather specific, right?), and I'm not talking about cool drifting, but more of the, "SURPRISE!"

Comments always welcome.
 
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