2002 chevy 1500 with 4l80

[Casey23]

I just put a 410/4l80 in my chevy 1500 with new GM speed sensors.. I used the speartech harness ... truck was apart for 3 months and now my speedo is off like crazy I installed new output speed tonight and its ok 0-10mph then tonight 80% throttle best i can make it read is 54mph !! truck shifts crazy hard and not very fun to tune/drive also the Brake/ABS lights are on now that i have this problem with a code of rear axle sensor... so is that where i am reading MPH now?...

[Casey23]

the truck had a new sensor installed and the known working used unit and bolth with the same troubles... Trans is Rebuilt/Truck had a new/different non proven PCM installed, speartech 80E harness with a new 80 Tune... Its all different !! I did test the wires to the PCM today .. The green wire is "low speed" from the sensor and it had .8ohms the purple/white had 1.8 ohms.. I didnt figure it was enough to kill the signal..so i removed the PCM from my daily driver 2500 installed and Reflashed my Tune SAME PROBLEM ... I will have a bend new GM sensor in the AM ... after that not sure what the next step will be.... something inside the trans?? .... I have tested/replaced everything that i cannot test with a meter.. i see no reason for these problems.... Nothing to do with my 3200 stall or anything??

[Casey23]

The problem isnt with the tune,or electrical.. problem seems to be mechanical...