The popping sound could be a couple of things first off is your wheel tight? check lug nuts. Some of other causes may be damaged rotors and pads. check them by removing wheel and looking for damaged parts or worn out pads. other things could be front wheel dive axle CV joint but you would hear this when turning also.

are the rear brakes disc or drum? i dont have a book on your car....either way, jack up one of the rear wheels, block wheels, put car in neutral and try to turn the wheel by hand.........next have some one step on brake pedal, and again try to turn the wheel. if you can still turn the wheel, your rear brake unit on that wheel is not working. do the same on the other same wheel.BE SURE TO BLOCK THE FRONT WHEELS WITH CHOCK BLOCKS SO THE CAR WILL NOT ROLL..........repost with results............................jl

I think I figured this out on my own. It is either the power brake booster or a vacuum hose. I will check both.

why does post title say chrysler?

Click on the link, fuse is in diagram. Does the highmount brake lite work? If it does, the fuse isn't the problem.
http://postimage.org/image/y2fhwyb47/

The sensor is a abs wheel speed sensor. You have to replace the wheel hub assembly.

does pedal vibrate when foot is on pedal?...is so check for bad shoes or warped rotors.

Try to remove the rear wheel for inspection; grinding brakes, worn brake rotor. Try the many on-line auto parts sources, such as; www.RockAuto.com or www.autopartswarehouse.com for the replacement parts.

You should have your brake system inspected, it is possible that one or more of your brake caliper pistons are jammed and or your brake caliper mounting pins or bushing are damaged.

Not necessarily, usually a scan is needed to verify. I mean, i know you will be pissed after replacing the ABS sensor and the code doesnt wanna clear right?
The ABS light comes on when the ABS module detects a fault in the ABS system. There are dozens of component failures and open/shorts in wiring that will set the ABS light, ranging from a faulty wheel speed sensor, open/short in wheel speed sensor wiring harness, faulty hydraulic unit, fault electronic brake control module(EBCM), faulty tone ring,etc. There isnt a relay or reset procedure to turn the light off- it can only be turned off by repairing the fault responsible for turning it on, and then using the factory scan tool to erase the fault code and reset the light.

While it is possible the majority of the faults to be repaired at home, the fault codes can only br retreived with a diagnostic scanner with ABS capability. This has to be done first in order to know where the problem is to either repair or do further diagnostics to determine if it is a faulty part or a wiring harness issue. If the problem is in the hyrdaulic unit, this would need to be replaced by a shop as it will require bleeding afterwards with a diagnostic scanner.

I would advise spending the $50-70 to have the on-board computer read for stored ABS fault codes. Considering that most sensors cost that much themselves, you can quickly sink much more than a diagnostic fee into replacing parts based on "what usually goes out" guesses.

Park the Concorde on a level surface. Remove two-thirds of the brake fluid from the master brake cylinder in the engine compartment using the turkey baster. Place the fluid in the drain pan for later recycling. Place the wheel chocks in front of the front wheels.

Jack the Chrysler up with the automobile jack. Place a jack stand under the car near the jacking point and raise it up to the frame. Remove the wheel using the lug wrench.

Remove the caliper bolts using a socket and ratchet and pull the caliper off the wheel assembly. Secure the caliper to the spring or shock for now with a wire tie. Do not let the caliper hang or you will damage the brake line.

Pull the rotor off the wheel assembly. Some cars may have retaining clips on the wheel lugs keeping the rotor in place. If your Concorde has these, remove them using the pliers. Put the new rotor on the wheel assembly and secure it with the retaining clips, if present. Cut the wire tie holding the caliper to the spring with the pliers. Place the back side of the caliper into the jaws of the C-clamp with the back brake pad in place. Close the C-clamp by turning it clockwise until the caliper piston seats within the caliper housing. Remove the C-clamp and the brake pads from the caliper.

Put the new brake pads into the caliper and put the caliper on the wheel assembly. Tighten the caliper bolts using the socket and ratchet. Put the wheel back on the Concorde and tighten the lug nuts with the lug wrench.

Remove the jack stand from under the Chrysler and lower the car to the ground. Repeat the process on the other wheel.