Service ABS and traction control systems is displayed in my 2005 pontiac montana sv6. New breaks have been installed and lights and system still on. Scanned and shows no sign of sensor issues

Check the wheel speed sensors. Traction control reads wheel speeds to know when a tire loses traction(it speeds up compared to the others). When the TC control module(computer) senses a problem such as a sensor out of tolerance, or an open circuit, such as a broken or disconnected wire/connector, it disables the TC and lights the light as a tell-tale.
Are you having trouble with ABS? Usually a wheel speed sensor defect will also affect the ABS too.

Could be loose caliper (unlikely but worth checking), bad pads (had them fall apart on me before when brand new), improper line bleeding (air bubbles in brake line), dirt on the rotor (brake cleaner will fix that. Remove tire and caliper, thoroughly spray down rotor, caliper and pads, let it completely dry and put back together). If none of those are the problem you may want to take it in for a brake system check, many places do that for free or cheap.

You will need to diagnose the code first. The traction control and abs systems are tied together, usually there is a bad wire on the front end. The way the wires are routed for the abs system makes for cut or pinched wires to one of the front hubs causing an open circuit to one of the sensors for the abs system. This causes the traction control system to quit working. Diagnosing the trouble code should tell you where to look

Have a qualified brake shop check this out ASAP>

the check stabilization problem sounds like ur ride control meaning ur air shocks in rear leaking or faulty compressor. traction control is possiblt an erratic reading from one of ur 4 abs sensors/or rings,anyhow u need to get ur computer system scanned for a more accurate fault description and possibly fault codes which will b very important in solving ur issues. good luck

Most likely when the ABS light is on,the system is turned off,don't know

I would go over the brakes real good, as I have zero faith in professional repairs,and then work on the ABS Code
Most likely a Wheel Speed Sensor

if the light is on there is codes some systems are not on the can bus network and require you too goo too that actuall computer in this case ABS module wicth also controls the traction control system and you will need a good scanner the 100 doller made in china ones wont do it take it too a shop they will probly get the info for a some fee it coul be one of the whel speed sensors or the abs module itself

One of the "hall effect" sensors may have a damaged lead, or the sensor itself has failed.

this means the ABS/Traction Control system has been diabled and all u have are regualr brakes without any traction control have the dealer or a brake shop test the system, there will be a system fault code that indicates where to look for the problem part or wiring.