a.b.s. sucks…

I'm just curious if it's enough to cause intermittent malfunction

Tire diameter/radius is a 'constant' in all ABS formulas; during the 'creation' of the system and related formulas, its value is pre-determined based on engineering of the vehicle and is meant to always remain constant.

This is why you'll see 'optional' tire sizes on the doorjamb and manual. For example on the Tundra (gen 2 and 2.5) it shows optional OE tire sizes as 255/70/18 or 275/65/18 for 18" wheels... These 2 sizes are both approximately 32.1 inches tall; yes I understand that will vary slightly based on tire MFR, air pressure, etc; but, my guess is that those discrepancies are marginal and accounted for within the calculations.

For the 20" tire option (plus 2 sizing) the recommended size is 275/55/20, which is just slightly shorter than the other 2 at 31.9" (or about .2" difference) or approximately .7 tenths of a percent difference (again marginal difference at best).

So, many folks mis-define plus sizing when it comes to tires/wheels... Stating that it's an increase in diameter. This is not true; plus sizing is a guideline to increase wheel size, decrease sidewall height and potentially increase tread surface width... but never diameter.



My point is, there has to be a reason for this beyond clearances, and my guess is that it deals with proper functionality of ABS, Trac Control, and other similar systems.

Many tire shops will only install tires that do not exceed overall diameter of the OE tire by 5%. I wonder if there has been information put out by system engineers that have stated this is the workable 'margins' for proper system function.

I'd also assume that within the formulas there are some 'variables' that are being accounted for that are 'unknown' such as the coefficient of friction (rolling friction) between the tire and the surface. This would make sense to have some flexibility in the system performance prior to 'taking over control' and engaging the system. IE>>> Sliding on ICE, loose gravel, etc....

I don't know if this is the reason the issues are coming up or not, but it's a thought. I've got over 275,000 miles of Gen2-2.5 Tundra service w/o ever experiencing this issue. I've also always ran only the OE tire size on my '08; primarily because it was always being used for towing, travel, etc. and I never had a need for a larger tire.

So, my theory if you will, is that if these folks are all running above (or below) OE tires on their rigs at the time of the incidents. Maybe the conditions, coupled with the 'inaccurate' tire size is creating a hiccup or exceeding parameters of the system and causing the 'failure'...

The only real way to test this would be for someone who can reliably produce the issue (normally on a larger than OE tire) to swap their tires for OE sized tires and then try to duplicate the issue. If they can't, bingo... if they can, then back to the drawing board!!!

 

Yup, happened to me 4 or 5 times. Hasn’t happened since I’ve been pulling the ABS fuse.

I personally think ABS is better 99% of the time for 99% of drivers. As someone who grew up on the track without ABS, I know how to threshold brake. But 99.99% of today’s drivers don’t. Like that first video @ColoradoTJ posted with the guy in the Miata. That guy is just locking up his wheels. Ofcourse you’ll lose control of the car. If he repeated that test with proper threshold braking, the result would’ve been similar to the test with the ABS enabled. Anyone who will panic and smash the brakes… ABS is for you. Lol. So I personally don’t think there’s much of an argument for removing ABS on everyday cars. It does help in the vast majority of scenarios.

With that said, it’s only happened to me on dirt and at high speed. But I don’t drive in snow and rarely even in rain as my truck isn’t my daily. And every time it’s happened, it was loose sand over smooth hardpacked dirt… it’s like trying to stop while driving on marbles. Basically, you’re pressing the brakes and because you’re on marbles, the brakes want to lock up. Your ABS won’t let that happen so it disengages the brakes. There’s nothing wrong with the system, it’s doing what it was designed to do. It just doesn’t work in this certain scenario. So basically your truck doesn’t even try to slow down and just keeps on trucking until you drive off a 4 foot ledge or drive into a large bush.

When the trip is over and I’m about to get back on pavement, I put the fuse back in. Although I can see this happening in the real world, especially on ice, it really doesn’t apply to me. I’d rather have ABS on pavement so I don’t flat spot my tires if I ever do a panic stop like Miata dude.

 

I think this is the downside of both always illuminated gauge clusters and/or automakers not making automatic lights standard, or if they are it's too easy for people to put their selector in the non automatic mode. GM had their shit figured out in 2007/2008 you could turn off auto with a momentary switch but every time you get in the vehicle it's right back in auto mode.

 

Touchscreens in cars. The main excuse when someone almost runs me over is 'i looked down to play with my a/c or radio for less than a second'...when i see those same people sit through half a green light.



sorry, forgot this wasnt the what annoys you about tech in vehicles thread.

living in texas i'm lucky that everything shuts down when it freezes, and i dont drive on bald tires in the rain, so i've never needed abs.

 

but then we're just putting another sensor on a sensor?

 

Yes. But that works on airplanes, they have that for some important systems, and when they mismatch it warns them, so the pilots can choose which they believe is working correctly

either way, having redundancy is proven to be safer and more reliable than one single point of failure. it is done in many other areas that strongly rely on technology

 

I’m trying to piggyback in this thread since it seems to be what i’m up against...

So i’m asking the collective, does anyone know where the 2004 ABS (and i suppose 2005-05 ABS) trucks get their speed sensing from?

-is it from a sensor on the back of the transfer case (4wd)?

-does it read the speed from the ABS sensors at the wheels? And if it is at the wheels, is it safe to conclude that it’s just the rear wheel sensors that relay that input to the speedometer needle?

-does the speed sensor wires travel through to the large ABS pump box plug?

-can the plug going into the ABS pump be disconnected and still have the speedometer still be functional?

-does the 2004-06 ABS 4WD trucks have a toothed speedo drive gear in the back of the transfer case?

-can the front ABS sensors be disconnected and still have a functioning speedometer?

The earlier model 1st gen 4wd trucks that did not have ABS had a 3 terminal geared speed sensor in the back of the transfer case. I’m currently trying to install a 2000 transfer case (out of a 2000 non-ABS truck) into my 2004 ANS truck. I’m trying to see what all i can purge and what i’ll i must keep in order to have a functioning speedometer...and NOT have ABS.

 

I have been a lurker for years and finally decided to post. On Saturday I came to a roll over accident on a slick road and I was going 5-10 mph and the people helping with the accident motioned for me to stop and the ABS would not let me and they were pissed and shouting at me but regardless how many times I let off and re-applied the brake I had to roll down my window and explain that the ABS wouldn't let me stop at 5 mph. If there had been people on the road I would have had to drive off the road. I had plenty of traction for acceleration. No slippage at all. As others have said I wish the ABS was disabled under 15 mph or so.

 

I pulled my ABS fuse. Triggered the ABS dummy light on the dash display, but speedometer works fine.

 

Same here. On the later models(starting in 05 I think) the fuse cannot be removed. We had to disconnect Johns sensor from the harness by the wheel. It also triggered the light but his speedometer still works fine.

 

Sounds like you've experienced what we're talking about.

 

As an update, i removed the ABS system from my 2004 AC. Since i also has a wrecked 2000 AC non-ABS parts truck, i performed a fairly clean conversion. I swapped over all the front hard lines off of the 2000 non-ABS truck over to the 2004. The hard lines have a threaded connection underneath the truck kinda near the rear of the front door. It was pretty simple to swap the hard lines since both had the factory bends in them. It would take a while lot longer, but it wouldn’t be too difficult to make and bend your own hard lines if you had to (i’ve plumbed completely new brake lines on a couple other vehicles that i own so i do have all the tools and experience though).

On my 2004 AC ABS truck the speedometer gets the reading from the rear axle...from the ABS tone rings that are pressed onto the axle shafts so be exact.

The front ABS wheel sensors don’t have anything to do with the speedometer. You can leave them in place or remove them (and the wires). But if you remove the sensors, you would have to go back and plug the sensor hole.

The speedometer gets its signal from the ABS pump that’s located under the hood (the large silver and black box). So you MUST keep that plugged in, BUT you can remove the large silver aluminum pump that’s attached to the black plastic module. If you decide to separate the pump it will create a fairly amount of usable space in that area. You could mount a second battery or an air compressor in that same spot.

I’ve been driving my 2004 tundra without ABS for about the past four months. I’ve been driving around in the snow and ice without any more or less issues than any other vehicle that doesn’t have ABS. The way the AC truck is balanced, it brakes in slippery conditions WAY better than any long bed single cab truck that i’ve owned (because of weight transfer). I’ve also towed LOTS of firewood while towing a trailer with LOTS of wood. No issues without having ABS there either.

Obviously ABS is a safety benefit for 99% of drivers out there. It’s up to the end user to decide if it’s right for themselves. Also keep in mind that i also have removed the entire ABS systems from multiple KTM 990 Adventure bikes that i’ve owned. I also have a 2005 Scion xB that i HAVE left the ABS system in place, but i have installed a bypass switch that shuts off both the ABS and traction control. I live in an area where there’s ice, snow, lots of gravel roads, and my xB literally would try to self crash itself into a ditch with the traction control activated.

A couple links to my ABS delete-
https://www.tundras.com/threads/tacoed-tundra-project.130491/page-7#post-3390345
https://www.tundras.com/threads/tacoed-tundra-project.130491/page-8#post-3401152

 

To update my comment, i had to plug the black plastic portion of the ABS module back into my wire harness. The back half of the module (the large silver aluminum block) can be removed and left out of the vehicle though.

 

My 05 Tundra nor my 07 4Runner (sold it) ever done this to me thankfully. I drove my 4Runner on snow/ice a lot too because my wife managed a store so I helped deliver groceries to their elderly/disabled customers every snow storm. I still remember the first "big" snow storm I drove the 4Runner in because snow was up to the grille. I had stock rims with new Duratracs & it handled it like we only had a few" of snow. I took it to an empty unplowed lot to test out its donut designs and with a V8 the damn thing hardly spun a lick with Duratracs on it. (I installed TC off button for donuts..lol). It always stopped perfect for me rain/snow/gravel/ice/dry alike. I drive on it all here in Central US. Toys 4wd's are remarkable snow machines with the right tires but not much stops good on ice. I remember my 4Runner had Michelin Radial tires when new & omg they sucked. Removed after first snow drive due to lack of traction . They'd send you in a ditch or pole no doubt about it.
My Tundra's a 2wd AC with just under 400k & the only issue with its brakes is the same damn thing my 1991 Toy Ext Cab suffered from is the load proportion valve on rear seized up. I just disconnected the rod from bottom (rear end) & tied it up as high as possible to maximize its rear braking. Truck(s) went through front pads/rotors quickly being the fronts mainly what stopped me till I tied rod up. Id suspect a bad/failing load valve on rear may cause or enhance the issue owners described here as it certainly prevents max braking force on rears. Maybe someone can test this next winter? Sorry' my health prevents me from testing much these days. Hell just goin #2 is my big test these days..lol
Peace

 

Every owners manual I've ever seen, up to my 2008 Sequoia, has warned that ABS increases braking distance. That is what it does, that is how it works.

My theory the ABS trying to kill you situation is simple.

When going downhill in mud, snow or gravel, there is a constant acceleration of gravity trying to make your truck go faster, call it G

You have your total braking force, B

You have the traction of a rolling tire, R, and the traction of a locked tire, L


When G exceeds L, you CANNNOT EVER STOP without locking your tires, but your ABS prevents you from ever reaching lock, so instead of slowing down, your truck just keeps going faster and faster while you stand on the brake praying.

It is a particular menace in a unloaded truck, because your rear tires have very little traction....but ABS, always has to reduce braking force, to keep the tire with the least traction rolling. This means in such a situation, your front brakes, are only allowed to do as much work as the rear brakes are....which as we know, are just drums, because normally they don't work very hard.

In short, ABS makes every wheel on your vehicle, brake only as much as the WORST wheel on your car.

ABS has provable increased crash fatalities across the board.

 

In snow going down a hill you also get the “plow” effect to help when trying to stop with locked wheels. ABS just prevents them from locking and won’t work because the traction isn’t high enough for it to work.

 

I wrecked my brand new Lexus because of ABS...someone pulled out in front of me so I smashed the brake pedal to the floor for a panic stop. But instead of screeching to a halt I experienced the brake pedal pulsing back at me while the car gradually decelerated, failing to stop short of the collision. Yes, ABS sucks!

 

I have had 3 Toyota vehicles from this era. 97 & 98 4Runners and 04 tundra. The abs system on these are very similar. The 97 I lost because of abs. On a gravel road driving conservatively at, my abs caused my truck to lose traction and control. I hit the berm, ass uped, then rolled taillights over headlights 3 times. Spilling my truck across the desert. I’ve searched for a fix for over a decade. This gen abs is flawed in low traction conditions. If you don’t believe, go to gravel safe place. Engage brakes 3/4 panic stop at 5-10 mph and feel the shake. Be smart, be safe. This is a real issue, only fix is to mod/delete for conditions then return to oe for safety/liability reasons.

 

Yes, roads that look exactly like that. Loose sand and marble sized gravel over smooth hardpacked dirt. Is that California desert? My truck would make a distinctive growling sound whenever it happened. Gave me a couple second warning to hold on and pray.

 

Probably going to pull the fuse on my 03 after I buy a scan tool and confirm that no particular sensor is causing the issue. Mine engages while turning at low speeds under 5mph (like pulling into the neighbor's driveway to reverse and make a u turn on a residential street) and I don't want it to happen in an emergency. I live in Southern CA and it doesn't snow here anyway and I drive the truck like a grandma. If I do take the truck to a snowy area once every 5 years or so, then tire chains are usually mandatory anyways and police literally have roadblocks and wont allow you to pass without them.Does anyone know if this triggers a trouble code/pending code on the OBDII (pulling the fuse)?

Just wondering if I'll have any issues getting the truck to pass smog every 2 years here or if it will turn the CEL on.

I have OEM sized tires by the way, recently adjusted the parking brake by manually tightening the drum brake adjusters (which fixed my low brake pedal), and wiped the sensors clean when doing a recent brake job. No difference. If mounting the sensors in a certain manner down to the thousandth of an inch to make the ABS system happy even matters, then I definitely don't want ABS on this car (if its THAT sensitive). Tone ring looked crystal clear when I peeked down into the hole with a flashlight with the sensor removed. Sensors were seated flush also upon reinstall and the wires were all in good shape. Brake fluid was bled properly as well including the LSPV. The ABS module also looks newer than everything else in the engine bay indicative that the previous owner may have replaced it trying to chase the same solution.

 

Does not make a CEL, just an ABS light.

Interesting enough, removing the fuses, doesn't even trigger a speed sensor code or abs code.

I know, because I've had the fuses out for years now, with no brakes codes, but this spring when I had a LBJ failure, the speed sensor wire was broken on that wheel....and I haven't fixed it yet, might not ever bother to, but it does show up as the only brake system error when running a code scan.

 

I once test drove a 10 year old 87 Corolla I was interested in buying. When I went to hit the brakes, they pulsed upon braking. Thinking it was the ABS I asked the owner if that was normal at low speeds on dry pavement.

He responded “What ABS?”. I told him thank you, I wasn’t interested.

That day I guess I learned what happens to disk brakes when they become severely warped.

 

If that was the only thing wrong with it, too bad. Warped rotors are one of the easiest things to fix on a car.

 

They were asking $3k for it at the time which was pretty high considering it’s MSRP was $9k and other corollas were going for $2-$2.5k at the time.