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Thread: 4l65e No overdrive? high rpm during part throttle

  1. #1
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    4l65e No overdrive? high rpm during part throttle

    Hello

    Could someone please take a look at my log file, and tell me what is happening with my transmission? I was driving home, and all of the sudden the car started to rev high and no power on the freeway. I think I lost overdrive, but I am not sure. Its a mad dog rebuilt transmission rated up to 500Hp around 15k miles on it. Its slightly overfilled and the fluid looks old but its definitely not brown. I did run up to 260F about 2 weeks earlier because I forgot to turn on the transmission cooling fan located under the car. No error codes, no strange noises. The scanner shows that the car is running into the 4th gear. Does the car actually go into 4th gear just like the scanner shows, or does the computer think its in fourth gear? LS2 engine with big cam ls3 top, ls3 injectors, ls3 MAF, LS3L92heads and, LS3 intake, headers, naturally aspirated. I hooked up the scanner and under special functions I commanded gears 1-4 while the car was off, I could hear them clicking also did the same thing with shift solenoids I could hear them click as well. The TCC solenoid did not click, but when I command TCC lock while the car is on and in neutral the car shuts off as soon as I put in drive. So does that mean that the TCC solenoid is working. I am planning on draining the fluid and replace it this weekend, what else would you recommend doing while the fluid is drained? I appreciate all of your help.

    UPDATE 1: I also added the current tune file.
    Attached Files Attached Files
    Last edited by ramonboghoz; 12-03-2020 at 12:32 AM. Reason: Tune File Added

  2. #2
    See if there is a PID for the actual 1,2,3,4 pressure switches and see if its actually is in 4th gear. It may say current gear 4th but that is just a command to be in 4th gear. You want to see if the 4th gear circuit is pressurized by the state of the pressure switch.

  3. #3
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    Thank you, I just checked and couldn't find any PID's for pressure switches, but there is Force Motor (PCS) Pressure Line, and when the log shows its in 4th gear the pressure line changes, and also Time of Latest 3-4 shift. Would this mean 4th gear is working?

  4. #4
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    So today I went for a drive and tried to see if could feel the car shift 3x and, it only shifts 2x. So no 4th gear? I will pull the servo and replace it with a new one and, new transmission filter when I am replacing the fluid. In case the 3-4 clutch goes out could it happen instantly or do you usually get warning signs? Does it also to start sounding any different than before? I also notice the transmission is starting to overheat above 200f after 40 min drive.

  5. #5
    Highly unlikely there is anything wrong with the servo you wouldnt have 2nd either. If then3-4 clutch is junk you will not have 3rd gear.
    Last edited by wildfan1976; 12-03-2020 at 10:10 PM.

  6. #6
    If you dont have 4th either the 3-4 clutch is toast or the band. Highly unlikely there is anything wrong with the servo.
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  7. #7
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    Thank you so much for your helping me diagnose my transmission. I never dealt with transmissions before, but with the lockdown I am unemployed and cant afford a mechanic, so I hope I can fix it myself. I am really confused yesterday I unplugged the big connector to put the transmission into limp mode, and it feels exactly the same. Since, the car goes to 50mph could I assume 3rd gear is working? So I cleaned the plug and put it back on, and went for another drive and at around 25mph I shifted to first manually on my shifter and could definitely feel the drop. So 1st and 3rd are working. I might be wrong but the car also has also spark problems because I have a small header flange leak and that's why maybe I thought shifts 2x where it shifts actually once 1st to 3rd. Its a SD tune using wideband so I don't think the header leak causes the problem.

  8. #8
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    So I dropped the oil pan, and didn't see any metal shavings, there was some grey grease looking material sticking on the pan floor. I also pulled the servo and couldn't find any problems either, I did order new seals for the servo and filter for the transmission I drained a whole lot of fluid from the transmission and the transmission cooler. Hopefully when i put it all back on Monday or Tuesday with new fluid and maybe some additives it works again.

  9. #9
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    So I put everything back together, and sealed the exhaust leak. Unfortunately no luck, I am gonna store the car until things get better. Maybe I will try with a longer servo pin next month from Sonnax. I read the longer servo pin could get 4th gear back on some cases.

  10. #10
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    Quote Originally Posted by ramonboghoz View Post
    So I put everything back together, and sealed the exhaust leak. Unfortunately no luck, I am gonna store the car until things get better. Maybe I will try with a longer servo pin next month from Sonnax. I read the longer servo pin could get 4th gear back on some cases.
    I had the very same issue. Russels automotive in oxen ford Gold Coast fixed it

  11. #11
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    looking at the tune provided its commanding 4th gear at a higher mph which u dont seem to accomplish.....from what i know a truck needs the mph in the table to command the shift...