Breake will not stop in low speed collision

most merc breaks are the same there are 2 bolts conecting the calipers to the hangers remove these pul the caliper off and put it on somthing so the breake hose isent just hanging
remove the old breake shoes shove the breake piston all the way back as far as it will go put new shoes in place and put calper back over the breake making sure that the springs on the shoes if any are seated correctley put the bolts back in not a difficult job if your any good with cars 1 of the easiest breaking systems i have ever worked on can do all mine inc hand breake in an hour good luck

one of the bulbs have blown

It sounds as if your fan clutch (or the electrical harness) is bad. Since you suspect front end damage, check for the harness and proper connection of connectors first.
The P0106 refers to the MAP sensor, it may require cleaning or again check the connector to it.
P0300 refers to random misfires, this could be any number of things, could be spark or fuel feed related.
The B0055 refers to the airbag module circuit. Again, if front end was damaged, the airbag sensors are in that area.
Good luck with this vehicle.

you need new brake pads

i think you may have two problems. First ,i think your caliper mounts are rusty. Remove the calipers , if the brake pads are not moving totally free , take them off , remove the pad sliders and file the rust off of the caliper mount and coat with anti seize. Put the sliders and pads back on if everything is free and working properly , reassemble. Next check your power steering fluid see if it dirty or has metal in it. If it is low top it off and see if that solves the problem. If it is dirty do a complete change of the fluid (muddy fluid can cause the pump to grind). If there is not too much damage the fluid change may fix the problem. If not you may be looking for a used pump or rack out of a salvage yard (no used parts out of a front end collision!!!!!).

When you said, the bleed valve had to be loosed before the caliper would release, (caliper is already replaced), then we know there was a lot of preasure in the braking lines backed up some where,
and every time the brakes are applied to compress the the caliper to stop your truck,
the preasure would not release,
This
Is a clear indication that the Flexible Rubber Brake Hose attached to the caliper is backed up, clogged, kinked, etc..
That would be the next item in the brake system to check.
Its Bottom Up Disagnostics...
When the hose is off try to slide a strong piece of wire (metal clothes hanger) through the hose..

SOLUTION:
Replace Rubber Brake Line's, on both sides.
I reccomend Stainless Steel Braided Brake Line.

Here is a video that kinda shows corrosion in a rubber hose.
Also check out other videos on youtube.

Check the speed sensors at each wheel. http://www.ehow.com/how_4521137_replace-abs-wheel-sensor-chevy.html

Have your insurance company involved and tell them the brakes are not working correctly. they should investigate the truck.

It sounds like you need a tune up and to clean the injectors take care of all the performance issues before you even begin the smog my suggestion would be plugs and wires and 100% that it can be your O2 sensor that is why your not passing that cost about $40 to $160 at a parts store and $40 to $90 to install good luck

Yes, if it didn't do it before the accident but now it is then call your insurance co. and let them know it isn't fixed and the symptoms. It could be anything. A bent steering component, warped rim, etc.