GM Drivetrain & Suspension Chassis | Transmission| Driveshaft | Gears/Rear End/Differential | Traction Aids

4l80e reverse only when unpluged

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Old Nov 16, 2013 | 09:47 PM
  #11  
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when in reverse and you push it back wards its like its in neutral you push forwards its like its in park. giving it gas it just acts as if it was in neutral or park
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Old Nov 17, 2013 | 03:24 PM
  #12  
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so to day i go and cut the wires one at a time to the pressure control soleniod nothing still no reverse tryed cutting the wires to the pressure switch manifold still nothing. i do not understand why i have great strong reverse when i unplug this thng but nothing plugged in. does the pressure switchmanifold have anything to do with the shifting? i know on the wire diagram it shows P R N going to it im thinking that stands for park reverse and neutral?
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Old Nov 17, 2013 | 05:04 PM
  #13  
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Do you have all 4 forward gears?
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Old Nov 17, 2013 | 05:27 PM
  #14  
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i have all forwards gears and lock up my tow haul works temp guage works everything works but reverse when its plugged in.
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Old Nov 17, 2013 | 05:45 PM
  #15  
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found this on a site

"If the control module senses a speed reference greater than 8mph during the shift into reverse, it has the ability to prevent the shift from happening. That being said, it is a very simple test to eliminate the electrical part of this one. Unplug the electrical connector to the transmission (this will force a fail-safe shift pattern eliminating the computer's ability to prevent the shift) and see if the reverse shift comes back

Answers to the test results of case connector unplugged:
•Reverse works: check for speed references to control module.
•Reverse fails: on to the mechanical test"
so does anyone know how to test the speed refrences t control module?
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Old Nov 24, 2013 | 02:20 PM
  #16  
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You have a internal problem. I would have your other transmission repaired. There are so many possibilities of what could be wrong. Short of taking it apart there is no telling what's wrong. Sorry I can not be more helpful
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