Does your car do this? (ABS Actuation at Low Vacuum)

[ctechbob]

Having primarily driven older Honda vehicles through the years, with my newest being a 2008, I ran across an interesting behavior of the ABS pump on my 2020 Ranger and was curious if anyone else had noticed that their cars are programmed the same way.

The situation was, Ranger was sitting at the top of my sloped driveway and I wanted to simply roll it down the hill to park it next to the door for the night. Moving a car 20 feet down hill doesn't require starting the vehicle, so I turned the key on, put it in neutral and rolled it down. Needing to stop at the end of the trip I wailed on the brake pedal as I expected no vacuum assist (since the truck wasn't running). What I got was an initial hard pedal (expected) followed by full-on activation and wheel skidding of the ABS pump.

I've never heard of someone programming a system to work like that, although it does make sense. If you're in a panic situation and the engine has failed, the car will take over and perform maximum stop to hopefully prevent you from hitting something solid.

Just found it interesting as I've never experienced that, and I suspect 99.9% of the public never rolls their car with the engine off, so they probably won't either.

 

[KGMtech]

Not something I'd ever think to do, as the risk of crashing would prevent me from trying. I'll continue to take your word on this fun discovery.

 

[Accent Abuser]

Strange. I've rolled my Accent before for a jumpstart but never happened to me. Actually the ABS on my car doesn't even activate (you can hear the mechanism click) until the car begins driving down the road at normal speeds.

 

[ctechbob]

Not something I'd ever think to do, as the risk of crashing would prevent me from trying. I'll continue to take your word on this fun discovery.

Very little risk of crashing, and in my opinion, one should know what it is like to stop a vehicle with no vacuum assist. Luckily I think most people's reaction to a stiff pedal and lack of braking will be to push harder, which is what you would have to do to stop the car.

 

[Propflux01]

Strange. I've rolled my Accent before for a jumpstart but never happened to me. Actually the ABS on my car doesn't even activate (you can hear the mechanism click) until the car begins driving down the road at normal speeds.

That's just the auto test system that comes on (IIRC) at 8mph. But has got me curious about enough it to go find a hill and try it!

 

[xgmad]

i dont even have abs the darn thing blew up