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P0740 (no symptoms help)

This is a discussion on P0740 (no symptoms help) within the Automatic Transmission forums, part of the Drivetrain category; This is an odd one- I've been reading up on it and I can't seem to get any solid definitive ...

  1. #1
    Junior Member Letzride's Avatar
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    P0740 (no symptoms help)

    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 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 took a scan of a ride around the block- I scanned some status bits as well as some transmission parameters- the TCC solenoid seems to turn on and off?

    I can email anyone interested in looking at it because I don't know how to attach a file in this forum


    Car still drives great, but as soon as I delete that code it comes right back- Im stumped??


    Help!

  2. #2
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    '02 WS.6 / '07 Suburban

    This may be useful: P0740 Torque Converter Clutch Circuit Malfunction DTC


    As it states, you may not experience any real symptoms. Unless you have a modified transmission you really cannot feel the TCC locking and unlocking. It may show the signal to lock and unlock, but may not actually be doing anything...

  3. #3
    Junior Member Letzride's Avatar
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    ya- thanks for the read.

    I read a few articles the other night- I tested the converter lockup by having the car in idle and commanding the tcc on while in gear (the car should bog or stall) and it did nothing, so I know the clutch isn't being activated.

    The why is now the issue, I might see if the shop can pull the pan down and test the harness somehow and solenoid, or I may just replace both because it is probably cheaper than diagnostic time.

    anyone have any ideas or speculations?

  4. #4
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    Are there any fuses or relays under the hood? I haven't looked so not sure. Wouldn't hurt to trace your harness to see if you have any damage, especially if you have headers. Hate to see you rip into the trans and have it be an external issue. If you need a TCC diagnostic, let me know and I can grab my factory service manual this evening.

  5. #5
    Junior Member Letzride's Avatar
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    I actually didn't even think about the fuses - I'll take a look tonight.

    I want to say this is an intermittent issue at the moment, although I couldnt get the clutch to come on with hp tuners, the code isn't a hard code right now, it is pending/immature for the last 2 days now. But if you delete it it immediately comes back as pending / immature.

    I'll go through the fuses tonight and let you know if I still need to see info from the manual. Do you know off hand if there are any wires that run near the exhaust piping under the car? I havent had a chance to look as I have been late getting in from work these past few days, but I did just have a new 3" Ypipe installed (then drove 12 hours) then the code came on after that 12 hours. I've wondered if there is the possibility of something that maybe melted? I can't remember what runs down there though and like I said, I havent had the change to get the car up and look underneath yet.

  6. #6
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    I want to say that the wires run down the passenger side of the engine compartment, fairly close to the exhaust. Been a while since I had our trans out of the car.

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