1989 GMC Sierra transmission problems

1989 GMC SIERRA
75,000 MILES
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MAGGIE78155
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  • 2 POSTS
recently changed fuel pump, battery and sending unit. removed the brain box and returned it immediately. tried resenting emc by taking cables off battery. Everything starting and running great except now while driving the transmission whines and shift extremely hard. I changed fluid and filter with no help. Can you give me some idea of whats wrong.
Jul 16, 2013 at 12:56 PM
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JACOBANDNICKOLAS
  • ✓ASE Certified Mechanic
  • 110,194 POSTS
  • ASE Certified Mechanic
It sounds like shift perameters are off. It may have to go through a relearn if you had the ECM out. It should reset within 100 miles. Try that and see if it helps.
Jul 16, 2013 at 7:01 PM
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MAGGIE78155
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  • 2 POSTS
Thanks guys, but figured it out it was a loose vacuum line.... Thank God.. Nothing too serious.
Jul 16, 2013 at 8:31 PM
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JACOBANDNICKOLAS
  • ✓ASE Certified Mechanic
  • 110,194 POSTS
  • ASE Certified Mechanic
That's good news. Glad you got it working.
Jul 17, 2013 at 6:13 PM
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