ABS Stutter

drmoreau

drmoreau

New member
Backed out of a parking space last night, put it into drive, then pulled forward a few feet at idle and when I came to a stop there was a short but loud (at least in the cab) series of clicks/pops and the truck seemed to judder to a stop. Almost felt like what a manual transmission car does when you stop without pushing in the clutch but the motor was still running, no warning lights were on and I'd felt it through my foot on the brake pedal.

It did this several more times, all as I was creeping through a parking lot behind slow cars. I wasn't breaking 3mph and it would only do it when the truck was extremely close to full stop. After we pulled out onto the road I used the handbrake to bring the truck to the next stop and after that it was fine the rest of the way home.

I've Googled it and apparently this is something that occasionally happens with 4Runners and Tacomas. Lots of folks seem to suggest axle wrap and all kinds of driveline things but trust me, this was not driveline (unless it's something I have NEVER seen/heard of before). I guess if it does it agan I will have to pull the ABS fuse but has anyone else had this issue and resolved it? I do normally get a little wobble from the front end as I'm slowing down so I assume I have some mildly warped front rotors, never heard of warped rotors causing ABS to freak out though.
 
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Still doing it this morning, but only for a couple of minutes when I first set off. It seems like once the brakes warm up it stops. In fact I can't even get the ABS to activate by cruising at 20mph and slamming the brakes on.

I tried pulling the fuse but it's some huge yellow fuse and won't come out, even with pliers :(
 
My ABS fuse was also very stubborn so I did it a different/easier way. Just unplug 1 of the connectors at the abs control unit (located at the back-left of the engine compartment if looking from the front). Once unplugged, you should now see the ABS light on the dash. Hopefully disabling will fix your problem at least temporarily.
 
Damn, problem is not fixed. It's so strange, if I take off and drive and come to normal stops I'm fine...but if I come to a quick stop right after starting up and going into gear (for instance you start up the truck and pull out of a parking spot but have to stop suddenly because the car in front of you does) then it "feels" like the ABS brakes kick in and you come to a really harsh stop (as opposed to the 4Runner's normal soft stop). Funny thing is I CAN'T get the ABS to kick in by going 40mph and smashing the pedal, in most cars I can.

It's a series of rapid pulses that you feel through the brake pedal and it also makes a noise and varies in intensity from time to time.

I can replicate it nearly every time if I just let the truck sit for a few minutes, then put it into gear, let it roll forward and quickly tap the brakes. Once I'm rolling for a short distance under power it won't do it again. Really strange.

I've seen others complain about judders from the driveline, is this possibly something related to the driveshaft?
 
Pull each sensor and see if any rust is stuck to the tip.

As for axle wrap, when you go over bumps does the rear scoot out? Or act like its shifting?
 
No, rear end seems fine. Whatever this is it seems like the brakes are grabbing really hard and sudden, it also seems like the driver side is catching better than the passenger as there is the feeling of a slight twist in the frame when it does it.

I tried pulling the ABS fuse, didn't help, and I also got the driveline inspected and the mechanic said the u-joints were all solid and looked good.
 
ki1022 said:
Vacuum leak or something wrong with the brake booster??
Click to expand...

I guess it's possible but just really strange that it only does it when I first put it into gear and haven't driven more than a couple of feet.

I have new rotors and pads coming in soon and will be changing that. I have some wobble when braking so that should fix that and I will also make sure neither of the calipers are loose and that the ABS sensors look undamaged.
 
Reviving this thread because I am having similar issues with my 97. I was getting an occasional violent shudder that is definitely not the ABS actuating. At first i thought it was a sticky front caliper but, rolling slow through a fast food drive through, the drivers rear wheel actually locked enough to squeal. So I opened up the drum and it was the cleanest drum brake set up I've ever seen in 35 years of working on cars.....except for a very small amount of oily substance on the drum just outside the area where the shoes make contact.
I'm thinking the rear seals are just beginning to fail but, just for the hell of it, I tried to get the ABS to work. Perfect conditions with it having just rained but I could not get the ABS to go...wheels would lock up.
Anyway - did you get anything definitive on this?
 
It only does it when the rear brakes are cold. I've found that in a line (dropping my daughter off at school in the morning) I can put the handbrake at the first click and it will prevent them from doing it.

When I had my rear brakes done I had the shoes and seals done, but I did NOT do the drums themselves. From what I've read on other forums folks have reported for years having similar problems with drums that are just the slightest bit warped. I'm going to wait until my shoes need replacing and then replace the whole kit and kaboodle.

Almost completely sure it's the drums being ever so slightly out of round when they are cold.
 
Thanks for the response. Just to be clear - you had the seals done as a preventative measure and there was no evidence of them leaking?
If you're symptoms are the same as mine, it seems impossible that a slightly out of round and only when cold drum would cause what I'm getting! But I'm going to try your P brake trick and will report back.
 
Have you bled the brakes at all recently? It's a long shot, but if there's air in the lines it could be messing with the booster or pressure differences if one line has air in it.
 
no they WERE leaking, but I had them fixed and had the rest of the brake hardware (save for the drums) replaced and it still did it.

just noticed one of my seals seems to be leaking again though :(

any idea how long I can safely go before replacing that seal? I really can't afford to do it right now. I don't drive much, less than 10 miles a day.

Mine, for certain, is not related to air in the lines. It's been to the shop several times for brake issues and they've bled it thoroughly.
 
drmoreau said:
no they WERE leaking, but I had them fixed and had the rest of the brake hardware (save for the drums) replaced and it still did it.

just noticed one of my seals seems to be leaking again though :(

any idea how long I can safely go before replacing that seal? I really can't afford to do it right now. I don't drive much, less than 10 miles a day.

Mine, for certain, is not related to air in the lines. It's been to the shop several times for brake issues and they've bled it thoroughly.
Click to expand...

It's not too expensive really. Although if it's a repeat offender, you'll want to replace the bearings and probably the rear differential breather (or clean it off real good). If you can find a shop to press the new bearings on the the axle for cheap, you can do the whole thing for about $150 if you do the rest of the labor yourself.
 
don't have $150 right now. also, when I do it I need to do the entire rear brakes at the same time to save on labor costs. I'll do just about anything on my own vehicle, including clutches, cv axles, motor mounts, etc... but I refuse to do drum brakes. they're just such a PITA..
 
I had my rear drums machined for about $12 each and this problem went away and has stayed away for +/- 3000 miles. I hope your fix is this easy!
 
yeah, I'm 90% sure that's what the problem is. in stop and go traffic I can even keep it from happening if I lock the handbrake at the first little click to keep them kinda warm. it's warped drums, has to be.

going to get this done ASAP
 
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