How to change internal filter allison lct 1000

Look at the RPO code sticker , driver door jamb , glove box , center console etc...
MG5
Transmission Manual 5-Speed, Getrag, 84mm, 4.00 1st, O/D
ML6
Transmission Manual 6-Speed ZF, 105mm, 5.79 1st, 0.72 6th, O/D

MT1
Transmission Auto 4-Speed HMD 4L80-E
MW3
Transmission Manual, 5-Speed, NVG, 109mm, 5.61 1st, O/D
M1F
Power Take Off Rear PTO
M30
Transmission Auto 4-Speed, HMD, 4L60-E, Electronic
M32
Transmission Auto 4-Speed, HMD, 4L60-E, Electronic, HD
M33
Transmission Auto 4-Speed, HMD, 4L60-E, Electronic, Hybrid
M74
Transmission Auto 5-Speed, Allison, LCT 1000, 3.10 1st, 1.00 4th, 0.71 5th, O/D, Conversion Clutch

The number you have 1GCEK14TX4Z322446 This is the vehicle Id# VIN doesn't tell you which transmission . The rpo codes do .

Whatever fluid u are referring to about checking either coolant ,oil, JUST CK IT WHEN THE ENGINE HASNT BEEN RUNNING

I don't know a "trick" but there are some youtube videos regarding allison transmissions.

did you try Allison dealer

look to this site for diagram or exploded view

http://www.makcotransmissionparts.com/mm5/graphics/Catalog-pdf/Allison-1000.pdf

This is part of the new Allison Prognostics. It's very similar to the oil life monitor on the new cars.

The way to clear the filter light after the filter is changed is to:

Turn the ignition on, but do not start the truck

Next move the shift selector in this sequence, N-D-N-D-N-R-N, do not stop the sequence for more than 3 seconds once you start.

This should turn off the filter light.

I would start
by changing both trans filters and fluid, makesure you put dex VI in trans then if still having problems take to someone with a Tech 2 scanner and have them reset the trans adapts and try that, what it does is resets trans to factory (new) mode and then as you drive the truck it will adjust to your driving habits and shift points, but loosing pressure makes me think one of your filters is partially plugged...there is a spin on cartridge and the internal one in pan, change em both..good luck

http://www.makcotransmissionparts.com/Chevrolet-GMC.html
you are stuck with the Allison 1000 tranny.

It is very cold .I put truck in R and the light blinks .I put it D it acts like it is in third gear.

Make sure you have the proper amount of tranny fluild in it and get that Valvoline fluid out of it. Allison transmissons have there own type of tranny fluid and you want to use it. You can buy the right stuff from a Allison dealer. Most Detroit Diesel dealers are also Allison dealers. Look them up in your phone book and they will tell you the quanity and sell you five gallon pails of the fluid. Just get the serial number off of the side of the transmisson before you call. Change the fliters again too. Believe me, this is important. My company has Yard horses with Allison transmissions and you don't want to screw with the small stuff. Service them right and they work as hard as you want.