Brake line getting red hot - 2001 Chevrolet Astro

FUSES BAD OR MODULES AND SWITCHES
NO BCM brain box here.
USA car , canada is NO THE SAME electrics !!!!
so flashers means turns, and turns are dead all 4 corners or what? all flasters is HAZARD lamps switch
parks work.(tails and front parks)
turns fail all 4 corners(not told) and hazards dead too all four corners and brake lamps all 3 rear dead.
do not break the brake lamps.
grounds to all lamps good,(the failed ones)
0vdc on ground.
fuses are always first, a 20cent fix. is way and childs play test (or a look)
fuse 1 and 9 not blown in IP BOX x2 , 15amps
OMG fuse 9 runs brake lamps. is this clue , YES
the next in LINE is Electronic flaster not bad.
5 wires and the black ground wire not busted.G204
next in line is the very complex MULTIswitch (column)
next is the BRAKE PEDAL switch NOT BAD.
if not bad 12vdc (push brake pedal) leaves the switch
R/GL wire to all brake lamps including 3 center high mounted lamp and its G300 ground

fix brake lamps only first.
fix that and others get fixed for free (shirt tails free)
to test lamps at rear for brakes the pedal must be depressed . a 2 man job.
fuse 9, hot both sides. and is hot all the time bat side.
brake switch LG/R wire hot all the time key off too.
light green red !
step on brake R/LG goes hot, now. if not switch is bad
Red/light green. (means)

I agree yada. In the diagram, the top wire is voltage to the brake switch. Goes hot with key on and is fuse protected. The second green wire with white tracer, goes hot when the brake switch is activated and carries voltage to stop lamps, that line with arrowhead moves to number 4 terminal. Part way through the wiring circuit, the wire color turns to green/red.

Sticking caliper, when it is cold the piston or glides don't move but when hot they slide better

sounds like they a warped because they got hot are these the rear rotors ? i would check for collapsed rubber lines, sticking calipers, sticking pads in the mounting brackets frozen e-brake cable the same can be checked on the front minus the e-brke cable

did both rear wheels get hot? if only one then perhaps the wheel cylinder is seized if both then maybe the pads are 2 thick or the master cyinder is seizing

Could be a bad master cylinder.

When you installed new calipers, did you bleed the lines out? Air trapped in the system can cause sticking. Unless they were sticking before you replaced all the parts. Try unplugging the ABS controller under the hood. If that does not work and there is no air in the lines then it would be 1 of 2 things.

1. Master cylinder failing to return.
2. Brake booster not providing enough vacuum.

Start the car. let it run for 10 seconds. while its running pump the brakes. let the brakes go and shut off the car. now press the peddle til it gets stiff. Now hold it down firmly. If the peddle pressure fades, replace the booster.

OK on the truck side, brake controller harness wire colors are:

RED = +12V (Hot at all times, even with truck off)
RED/GREEN = Stop light (Hot when brake pedal is depressed)
BLACK = Ground
BROWN/WHITE = Brake out (variable voltage to trailer brakes, 2v-12v)
RED/BLUE = Dimmer (not used on most controllers)

On the controller side (these are pretty much universal):

BLACK = +12v
RED = Stop light
WHITE = Ground
BLUE = Brake out

They're turning hot because you clamped off the rear lines. Now the fronts are being overworked - they're heating up because they're doing 100% of the stopping instead of the usual 70% or so. Replace the line and bleed the system before you destroy your entire braking system.