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Thread: Old truck with 5.3L/4L60E won't downshift in "OD"

  1. #1
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    Old truck with 5.3L/4L60E won't downshift in "OD"

    I've got an older silverado with a swapped 2007'ish 5.3L with 4L60E attached. The truck seems to start in second even when flooring the gas, and will shift into 3rd & 4th fine. But while in "OD" it will not start in 1st gear, or downshift at all when applying throttle. I can force it to downshift manually with the shifter on the column, but it won't do it on it's own.

    Can someone give me a sanity check on this tune and make sure I'm not missing anything? I've disabled all the TPS fault stuff that might cause an issue. Any help would be appreciated.

  2. #2
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    Do you have the gear selector switch and speed sensor hooked up? Can you shift the gears using the scanner controls?
    1997 Trans Am WS6 - LS1 swap - TR224 - Pacesetter Longtubes - Yank SS3600
    - 3.42 Moser 12 bolt - Wilwood Brakes - HP Tuners tuned - P1SC-1 Procharger

  3. #3
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    Quote Originally Posted by flame View Post
    Do you have the gear selector switch and speed sensor hooked up? Can you shift the gears using the scanner controls?
    I've tried it with the selector plugged and unplugged. Also swapped speed sensors to see if that helped. Nadda.

    Grrrr

  4. #4
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    You have to utilize the tools that you have. Use the scanner to see if the tcm is getting the required data. Then use the scanner controls to shift the trans. I'm willing to bet it is missing an input.
    1997 Trans Am WS6 - LS1 swap - TR224 - Pacesetter Longtubes - Yank SS3600
    - 3.42 Moser 12 bolt - Wilwood Brakes - HP Tuners tuned - P1SC-1 Procharger

  5. #5
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    "A4 select" gear selector in the scanner does not change anything. It will not shift the trans regardless of which gear I select.

    Wiring issue?

  6. #6
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    Here is some info to help but you are gonna have to dig in and start checking things
    1997 Trans Am WS6 - LS1 swap - TR224 - Pacesetter Longtubes - Yank SS3600
    - 3.42 Moser 12 bolt - Wilwood Brakes - HP Tuners tuned - P1SC-1 Procharger