Brakes and wheel locks on Chrysler Minivan 1996


#1

Hi, the wheel and brakes simply lock up while the engine is still running. That is the wheel can not, or with great difficulty and only a tiny bit, be moved and the brakes cannot be pushed down. I did try to pump the brakes four times when the engine was off and each time the pressure increases which I think was a test for brake boosters being OK? The way I got out of this situation was to get off the gas pedal, down shift, close the engine while on the road still and then quickly starting up again, and up shifting to Drive at which point all is normal. It happened before but I was not able to discern if the engine was running or not at that time ( initially when this happened I though the car had stopped actually) but this time there were no fans, no sounds, and a very empty road so I was able to tell that the engine indeed stays on the whole time this happens. I will take this car in but am trying to understand more about this kind of problem. Grateful for any help.


#2

I believe you’re saying (with some exaggeration) that the power steering and power brakes are losing their power. It’s hard to picture something other than a stall that would cause both of these to happen at once. Are you really sure the engine is still running? If you push the gas pedal down, do you hear the engine revving?


#3

It is definitely running. I have to actually stop it myself and start it up again. I am more worried than if it stalled as I think it may be brake related? Thanks for reading it and answering!


#4

You’ve misunderstood the test for brake booster function. The test is to pump the brakes with the engine off to “bleed” the vacuum from the booster, than while holding the pedal down turn the engine on. The pedal should soften and sink a bit.

But, that only tests for one function of the booster. And it isn’t the problem you’re having.

It is possible that your booster is either defective or misadjusted, or the pedal hanging up on something. Perhaps the stop is misadjusted not allowing the pedal to come up fully. The way the booster works is that it contains a diaphragm in a can. When the pedal is released, vacuum from the engine is applied to both sides of the diaphragm. When the pedal is pushed, the rearward side of the diaphragm is vented to ambient and the vacuum is applied to only the front side. The vacuum on the front of the diaphragm helps pull the road that pushed the pistons in the master cylinder. If the rod is not allowed to return completely due to a sticking diaphragm, of the booster is allowing the rear side of its diaphragm to remain vented, or if the booster itself is allowing the backside to remain vented, the engine can apply the brakes as you drive.