Torque Convertor Not Locking Up 4l60e 95 K1500 sub

Discussion in 'GM Powertrain' started by rdnkdrummer, Nov 29, 2012.

  1. rdnkdrummer

    rdnkdrummer Rockstar

    Hey y'all, I've seen a few topics that address this in different ways but none with the same basic symptoms as mine...all shifts nice and firm, but absolutely no lockup.

    This is a used 4l60e with it's TC out of a mid 90's K1500 pickup. I just installed it as-is into my 95 K1500 Sub. All I did was replace front pump seal, change filter & fluid, & wash it off. Shifts great, but no lockup whatsoever.

    I checked all the electrical connections & read it looks like I need to plug up the scanner & make sure the PCM is sending a lockup command?

    And if it is, I need to replace the TCC Solenoid, right? Sounds easy enough...someone tell me if I'm wrong here... Please and thank you :)
  2. rdnkdrummer

    rdnkdrummer Rockstar

    Bumping this...upon further investigation:

    No transmission codes, no engine codes, PCM is sending Lockup command. Fluid level good, color nice & red & new smelling.

    Still great lockup whatsoever. Help Please!!

    Any further thoughts?
  3. moogvo

    moogvo Epic Member 5+ Years 1000 Posts

    I'm drawing a blank here... Just replying so you don't start thinking that we are ignoring you! (plus a free bump-ola)
  4. dpeter

    dpeter Epic Member 5+ Years 500 Posts

    How does one tell whether the TC has locked up or not? For sure, without guessing.
  5. rdnkdrummer

    rdnkdrummer Rockstar

    I can only speak to 700-R4 and 4L60E transmissions. But basically the process goes like this when it's working correctly:

    Starts in 1st gear, shifts to 2nd, shifts to 3rd, then lockup, then 4 (OD). It will feel like 4 separate shifts if your transmission is set up and working correctly.

    Ways to check if Converter is locked up:

    • When cruising at highway speed in 4 (OD), while you still have your foot on the gas, barely touch the brake pedal. The RPM's should jump up a few hundred. This is the converter un-locking. If RPM's don't go up, it's not locked up.
    • If you know you're in 4 (OD) and the RPM's go up without downshifting when you're climbing a hill, the converter is not locked up.
    • When it's locked up, your transmission should feel like a normal stick shift would, you can just "tell" the transmission is locked to the engine RPM, no torque converter slush/slip when climbing hills, accelerating slowly, etc.

    - - - Updated - - -

    I'm gonna replace the TCC solenoid and see where that gets me. Will update :)

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