2007 Cadillac CTS: Brake System Locking up?

Suddenly while driving at highway speeds the Anti brake System gets locked up.
The Garage said there is no leak detected at any tires.

This is actually low pressure in tire problems.
It can be any of the tires problem.
Either front tires are getting low or rear tires are getting low.
The pressure in all the tires should be similar,if not then there rotational speed will differ and this causes the Brake system to get locked.

In most cases the problem is noticed on rear tires.But dont ignore front tire inspection too.

Yes, low tire pressure will definitely cause the ABS to activate and lock up. This is because one rear tire with lower pressure rotates at a different rate of speed, which causes different rates of speed being registered between the left rear and right rear tire in the ABS/Traction control control module and causes the locking up.

This is something commonly overlooked when diagnosing this problem and you wind up replacing all the wheel speed sensors for no reason.


Difference of 3psi is enough to cause the activation due to different rate of rotational speed. It isnt by how low one tire pressure is, but difference between the right rear and left rear tires.for example if both are at 30psi, all would be good as far as ABS. But if one is 35psi and one at 32psi, then this difference between the 2 is enough.

Try filling the Air in to the tire in which the pressure is tested low then other 3 tires or other two tires.Now if this problem goes away but again returns in few days or weeks,then you know there is definitely a air leak from tires.
By you putting more air into the one, combined with it only happening before when a tire was low, the we know 100% that this is the cause of the ABS activation and nothing else.

As per me i think the garage has failed to trace the leak.Some time the leak is very minute and takes time to get detected.
As to them missing the leak, yes it is very possible to miss finding a slow leak when tire is put in a tub of water unless it is soaked for several hours.

The best thing would be to go ahead and replace the tire that keeps going low or have them keep it all day in a tub of water until the leak is identified and fixed if possible or replaced. Most of the time a very slow leak is either at the valve stem or around the bead of the tire at the rim.

If it locks up on the higway all you can do is try to control the skid.

One alternative until the leak is identified and repaired would be to remove the ABS fuse in the engine compartment fusebox. This will cause the ABS light to come on until fuse reinstalled, but would disable the ABS system and prevent it from locking up until tire issue resolved.

This details will help.

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