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Thread: 4l80E 4x4 swap Speed Signal

  1. #1
    Potential Tuner
    Join Date
    Apr 2017
    Posts
    2

    4l80E 4x4 swap Speed Signal

    Hey gang, I've got a customer with a K5 Blazer that has a GM 6.2 525 horse crate engine swapped in running an E67 ecm. He originally had a th400 behind it, but has swapped to a 4l80. A local transmission shop installed the transmission and adapted the original old school K5 transfer case to it. They installed a BP Automotive ls swap harness and it has a dakota digital speed sending unit for the corresponding dakota digital dash kit in the transfer case. Problem is, the vehicle's computer has no clue how fast it is going with no speed input, so shifting is all over the place. The input and output speed sensors on the side of the transmission are in place and plugged up into the harness, but there is nothing after the transfer case reporting back besides the one sending unit going to the speedometer itself. What would be the best solution for getting a speed signal into the ecm?
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  2. #2
    Tuner in Training
    Join Date
    May 2016
    Posts
    15
    There are several codes for the transmission that are disabled. The PCM may not be seeing the transmission parameters.