hit a speed bump at speed activates my ABS brakes
- Thread starter hill
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I was under the impression that the ABS light only comes on when it requires service, not when ABS is actively being applied...?
The ABS can activate over a speed bump if one axle becomes airborne, and if your foot is on the brakes at the time that axle will lock. The ABS senses a differential between wheel speeds (front axle to rear axle) and activates. It can do the same thing with a pothole or series of bumps- if any wheel loses traction while the brakes are applied, the ABS can activate.
-Spike
- Joined
- Dec 24, 2003
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Right, but if I'm reading this right, he's saying that the ABS is activated WITHOUT hitting his brakes, I'm saying that unless something's seriously wrong, that is not happening.
It's not going overly fast that causes it... there are two spots that I can replicate it every single pass.
1. Leaving my college parking lot there is a decently sized pothole, as I drag my brakes to stop from 5mph it kicks on ABS and I have to completely let off the brakes.
2. Coming off the highway ramp coming home from college; braking from 75mph there is a big spot where the asphalt changes to concrete and it locks up ABS.
That said, I've never had it caused by braking over a speed bump.
I was thinking the same thing. I've never seen my ABS light come on, and I was just testing my ABS on some gravel the other day.
I'm not particularly observant, but I think I'd have noticed a red light during my repeated lockups.
I wonder if one or both of your ABS sensors is loose....
They have a little metal "tongue" that hovers over the ABS rig on your birfs. I wonder if the high-speed impact jars your axle enough to irritate the sensors. It wouldn't happen when you're wheeling because you're going slow. But at 40Km/h that might do it.
They have a little metal "tongue" that hovers over the ABS rig on your birfs. I wonder if the high-speed impact jars your axle enough to irritate the sensors. It wouldn't happen when you're wheeling because you're going slow. But at 40Km/h that might do it.
Same, I feel like there is some mischief going on with your ABS sensors that is causing this; IE the jarring causes them to give false speed readings momentarily and the ABS ECU interprets this as "oh s***, he's braking and locking the wheels" and tries to modulate pressure that isn't there.
Just what it sounds like to me. Go give your ABS sensors a quick one-over.
Sorry I don't have my Cruiser with me so I can't take pictures today, but if you look just inboard of the brake backing plates on your front axle you will see a cylinder about the size of a roll of quarters, with a loom coming out the top and leading to the wiring harness. Those cylinders are the sensors. I forget if they screw in or if there's some sort of lock-nut, but my first step would be just to wiggle them and see if there's any play. I would also test the circuit.
You will? All I see is a wire leading to a plug on the top of the knuckle.
The sensor is held in with a bolt.
-Spike
it's been a while. I guess the cylinder sits recessed into the housing? Don't make me go under there!
