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.