Anti-lock brake problem
 

I have a 2011 HHR that has anti lock brake problem when the weather is cold. Brakes work fine all summer and when it starts to get cold the petal goes almost to the floor. If you pump the petal it seems to be okay. I think there is a problem in the valve body. If I remove the lines to the valve body and plumb the brake system for no anti-lock what will the computer do? Will I just get a error code that I can ignore? Will the rest of the car still work? The brake system would be like the old days where a human will do the pumping when the roads are slippery.

It might just need to have the abs system bled with a scan tool.

One of the functions of the module is the proportioning valve.
I can't think of any reason temperature would affect the brakes, other than cracks in the rubber parts.

Sometimes, if the rear brake adjusters aren’t working properly, they never self adjusts and excessive travel makes a low brake fluid condition and causes air in the system. Before you bother bleeding, address the rear brake adjustment.

It might work to brisky back up and then firmly applying the brakes. Do it about 20 times. This was my experience; my wife backs up very gingerly, and apparently never applies the brakes firmly enough to advance the adjusters. I did end up getting the rear brake serviced anyway.

Here in Minnesota it has been really cold for a couple of weeks so most of the streets are clear of snow and ice. The brake problem has cleared up so it is not the cold that causes it like I thought. It starts when I apply the brakes and the street is slippery and the anti-lock brake system kicks in. The car make a lot of noise and shakes very bad and then I lose half my brake petal. It would come back if it warmed up for a couple days so I thought the temperature had something to do with the problem, but that does seem to be the case with our current cold spell. So I am still interested in know if I plumb the brake system like before anti-lock how will the computer react to no anti-lock system on the car?

Probably illegal to tamper with a safety related system. If you get in an accident, insurance might say that you're on your own.

We can’t advise you on tampering with a safety system on your car.
I replumbed a 1972 Austin Marina from diagonal brakes to from and rear dual system, it worked great but it wasn’t allowed to pass safety inspection as it was not OEM .

With the symptoms in my last post what might be the possible problem. I have decided to fix the problem or take it to a shop and have them fix it. Any idea what the costs might be. I have always done most of my own repairs on my daily drivers, but at my age I am not as eager to do that anymore. I would rather work on my older cars.

First off inspect , clean and lube the front brakes and calipers and pads, slider pins.
then the rear drum brakes, clean and lube tge shoe contact points and adjust the shoes until they just make contact with the drums .
If the EBrake lever is more than 3 clicks, adjust the cables.
now inspect the master cylinder, how full is the fluid? What colour is it?
thats a start. And I like to start with the simple basics first to eliminate any unnecessary things that could cause a problem.

You decide if you do this or a shop, that will hurry thru and charge you accordingly