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  • P0740 (no symptoms)

    This is an odd one- I've been reading up on it and I can't seem to get any solid definitive answers on it if you don't have symptoms. It seems that everyone who throws this code has noticiable transmission symptoms

    I'm throwing P0740 (for the TCC) in my 2002 ls1 camaro (stock 4L60e / stock stall) and I have no sympoms- my car shifts fine, 1, 2, 3, 4 and I am pretty sure it locks up as the rpms stay low enough? Although I am not 100% sure unless I scan it

    Shifts aren't harsh, I do have a bit of a misfire, but Ive had that since last year and I am pretty sure it is from the back most spark plug that was the only one I couldnt get to to change (but will be sometime this summer)

    Does anyone have any ideas of where I should start looking if I am not showing any symptoms other than the code (everytime I clear it and go for a short drive it comes back)

    I just got back from a 6 hour road trip (each way) and she was beautiful- I reinstalled my wideband O2 sensor today and found out the sensor is fried, then right after I got this TCC code, I pulled the fuse out for the gauge just incase it is an electrical issue, but that doesnt seem to fix the problem.

    I can scan it with hp tuners tonight- but what do I scan for? input/output shaft speed variation? what else? are there tests I can run with hp tuners to rule things out?

    Help!

    2002 SOM Z28 Camaro - 12.9 @ 104 mph
    1996 3800 Camaro - 13.43 @ 100.77 mph


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  • #2
    Re: P0740 (no symptoms)

    I don't think the scanner will pick anything up. Are you going to do any upgrades besides a aftermarket Tq converter? I would do a Transgo shift kit to firm up your shifts and while your at it maybe replace some of the solenoids to see if it makes the PO740 code go away for good. Got to figure it still has over 12 years on the tranny.
    08' L76 6.0L 4X4 Chevy EXT.Cab LTZ Vortec MAX with Snug top cover, Dynomax exhaust,Hptuners& K&N intake
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    • #3
      Re: P0740 (no symptoms)

      I don't want to do any tranny mods until I figure this out- apparently the stall could throw this code, so I don't want to mask a problem and tune the code out when there could be something underlying.

      I wasn't planning on a shift kit at this point in time, but this is all depending on what the issue turns out to be.

      Hp tuners shows all the solenoids kicking on and off while driving, and the TCC solenoid goes on and off as well- so not sure what the issue is. Everytime I delete the code though, it immediately fires back into pending, so something is up.

      I'm hoping I just frayed a wire with the big 3" Y-pipe underneath- but I just go back from a 6 hour 1way road trip, so 12 hours of driving should have killed a wire and set the code long before I got home Sunday and I only started throwing a code Monday- oddly right after I wired up the wideband and line lock wires into the car- but nothing is connected, and nothing was unplugged other than 2 grounds which I just double checked and they're all good.

      I'm stumped- I'll look under the car tomorrow night, but I don't think I am going to see much

      2002 SOM Z28 Camaro - 12.9 @ 104 mph
      1996 3800 Camaro - 13.43 @ 100.77 mph


      Project Cars | How To Guides | Scratch Repair | Synthetic Oil

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      • #4
        Re: P0740 (no symptoms)

        http://www.obd-codes.com/p0740

        You can try locking the converter while idling in gear while stopped. If the engine stalls the converter clutch is working, if there is no difference it's not.
        Last edited by bigbrian442; 05-21-2014, 02:45 AM.
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        • #5
          Re: P0740 (no symptoms)

          AHA- making progress, I actually scanned for that last night

          When I command it on with hp tuners, the engine doesnt bog or stall out. So I am guessing that the clutch is not actually being applied

          I'm terrible at electrical diagnosis, so I don't really understand a lot of what is in that link or a few others I have found.

          Is it still possible this is an electrical problem within the transmission? Can I use Hp tuners to begin ruling out possible causes for the clutch not being applied?

          I also found this article which is basically a diagnosis tree- unfortunately I don't have any of the tools it asks for (all electrical) but can hp tuners substitute a lot of the diagnostic devices being used becasue it can trigger solenoids etc?

          Here is the article: http://www.hotrodlane.cc/New%20LS%20...%205.7%20L.htm

          2002 SOM Z28 Camaro - 12.9 @ 104 mph
          1996 3800 Camaro - 13.43 @ 100.77 mph


          Project Cars | How To Guides | Scratch Repair | Synthetic Oil

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          • #6
            Re: P0740 (no symptoms)

            I'd start with the TCC solenoid in the trans pan.
            sigpic

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            • #7
              Re: P0740 (no symptoms)

              am I risking damage if I drive the car as is without the lockup coming on?

              2002 SOM Z28 Camaro - 12.9 @ 104 mph
              1996 3800 Camaro - 13.43 @ 100.77 mph


              Project Cars | How To Guides | Scratch Repair | Synthetic Oil

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              • #8
                Re: P0740 (no symptoms)

                You could overheat the transmission driving for extended periods at highway speeds.
                sigpic

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                • #9
                  Re: P0740 (no symptoms)

                  Good thing I sit in stop and go traffic for 12km every day then lol.

                  I'll look to get it into the shop this week and have them drop the pan

                  2002 SOM Z28 Camaro - 12.9 @ 104 mph
                  1996 3800 Camaro - 13.43 @ 100.77 mph


                  Project Cars | How To Guides | Scratch Repair | Synthetic Oil

                  Comment

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