bad transmission due to all of the fluid going out from a bad hose on cooler

1999 GMC SIERRA
300,000 MILES • 4.6L • V8 • 2WD
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LEONARD EVANS
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  • 1 POST
I have a transmission that all the fluid was blown out because of a bad hose on cooler. I replaced fluid and now it moves and changes gears until it heats up to operating temperature then it slips until it stops moving. i was told by a repairman automotive transmission specialist that the computer had to be reset after installation of another transmission was wondering as to why?
Dec 15, 2016 at 8:27 PM
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STEVE W.
  • ✓ASE Certified Mechanic
  • 15,200 POSTS
  • ASE Certified Mechanic
The PCM and transmission talk and adjust things like transmission pressures and shift points. It is very likely that the damaged transmission has set error codes in the PCM that cause some items to switch to default levels. When a new or rebuilt transmission gets installed you want to wipe that data out so the transmission can operate correctly.
Dec 15, 2016 at 9:04 PM
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