90 Buick LeSabre 4T60 Trans TCC solenoid question

Discussion in 'Transmission Forum' started by JackC, Aug 9, 2016.

  1. nickb2

    nickb2 Wrench. I help when I can

    Joined:
    Nov 22, 2008
    Messages:
    7,616
    Likes Received:
    109
    Gender:
    Male
    Occupation:
    Diagnostic tech
    Location:
    St-Hyacinthe, Quebec, Canada
    Cuz a flat spot on the TPS would show up and not code maybe, but drive-ability would still be affected at mid throttle with TCC disconnected.

    I know there is a height adjustment for the TPS. That can easily be checked.

    I am just not seeing the correlation.

    I understand what you are saying that the ECM is seeing the flat spot and commanding on and off the TCC, so to forsake a useless debate, tell/explain how this relates. Cuz I have never seen this before. And I do have a few clients left with these old buicks.

    Never too old to learn.

    Sorry for question, I am just like curious George. Once a grease monkey always a grease monkey

    cg-overlay-img.jpg
     
  2. nickb2

    nickb2 Wrench. I help when I can

    Joined:
    Nov 22, 2008
    Messages:
    7,616
    Likes Received:
    109
    Gender:
    Male
    Occupation:
    Diagnostic tech
    Location:
    St-Hyacinthe, Quebec, Canada
    I would think that if that is the problem, easy to check with a DVM or scanner.

    Potentiate sensor, 3 wire with a ECM 5 volt signal. So 2.5v should be expected at mid throttle.

    Best way to check flat spot, ohm it very slowly.

    I guess now that I am going to get schooled, and looking forward to it.
    ;):bat:
     
  3. nickb2

    nickb2 Wrench. I help when I can

    Joined:
    Nov 22, 2008
    Messages:
    7,616
    Likes Received:
    109
    Gender:
    Male
    Occupation:
    Diagnostic tech
    Location:
    St-Hyacinthe, Quebec, Canada
    Fixed another variable cam car yesterday, last night. Again, another actuator. These gm variables are really in need of a recall.

    It's easy to make fast $ in this trade. They just don't make them like they used too.
     
  4. nickb2

    nickb2 Wrench. I help when I can

    Joined:
    Nov 22, 2008
    Messages:
    7,616
    Likes Received:
    109
    Gender:
    Male
    Occupation:
    Diagnostic tech
    Location:
    St-Hyacinthe, Quebec, Canada
    spec snapshot

    Screenshot (797).png
     
  5. nickb2

    nickb2 Wrench. I help when I can

    Joined:
    Nov 22, 2008
    Messages:
    7,616
    Likes Received:
    109
    Gender:
    Male
    Occupation:
    Diagnostic tech
    Location:
    St-Hyacinthe, Quebec, Canada
    Oops, talked out of my arse again, there is/was a recall for cam position actuators.

    August 2011 letter from Chevrolet - 2011 Equinox with 2.4L recalled to repair camshaft position actuator solenoid. Result of problem is rough idle, poor driveability, and/or stalling at low throttle opening.

    But this is for another thread. Since I had time to spare today, got carried away.

    :cool:
     
  6. billr

    billr wrench Staff Member

    Joined:
    Mar 12, 2007
    Messages:
    5,752
    Likes Received:
    55
    No, Nick, disconnecting the TCC just prevents it from responding to bogus command signals that are caused by the TPS.

    Jack, I'm heading out of town tomorrow for a week or so, but I will leave the Snap-On out on the back of my Corvette. Is that Trans Pro on the corner of 3rd and N. Main? I was just next to it yesterday to get one of my Saturns smogged!
     
  7. nickb2

    nickb2 Wrench. I help when I can

    Joined:
    Nov 22, 2008
    Messages:
    7,616
    Likes Received:
    109
    Gender:
    Male
    Occupation:
    Diagnostic tech
    Location:
    St-Hyacinthe, Quebec, Canada
    Thx Bill, so I hope the specs I gave for the TPS will help. Good run to see Jack and say hi.
     
  8. JackC

    JackC wrench

    Joined:
    Nov 14, 2006
    Messages:
    1,376
    Likes Received:
    14
    Gender:
    Male
    Occupation:
    Retired
    Location:
    Nothern California
    Jack, I'm heading out of town tomorrow for a week or so, but I will leave the Snap-On out on the back of my Corvette. Is that Trans Pro on the corner of 3rd and N. Main?

    Bill: Yes-- 3rd and Main. I will do some more diagnostics when the car is available in a week or so. Therefore will probably not get the Snap-on.
    But thanks for thinking of me, maybe later.
     
  9. JackC

    JackC wrench

    Joined:
    Nov 14, 2006
    Messages:
    1,376
    Likes Received:
    14
    Gender:
    Male
    Occupation:
    Retired
    Location:
    Nothern California
    Drove the 90 to Trans Pro and they thought it was a bad TCC solenoid and quoted from $1000 up because the side pan is so hard to remove. More than my friend would put into this car. They agreed that cutting the wire to the brake TCC switch would work to eliminate the TCC altogether.

    I had my OTC scanner connected during the trip up there and the car did buck even with the TCC commanded ON. That would seem to prove that it is the TCC solenoid or an engine miss and not a sensor into the ECM.

    But that still does not eliminate the TPS making it buck instead of the TCC solenoid going off and on, except that it did not buck when the TCC plug was disconnected. ???

    But I will take BP's advice and still check the TPS

    So, I think we can call this closed. Thanks for all the help.
     
    Last edited: Aug 10, 2016
  10. billr

    billr wrench Staff Member

    Joined:
    Mar 12, 2007
    Messages:
    5,752
    Likes Received:
    55
    If the TCC was being commanded "on" steadily, then I doubt the TPS is the problem. Is that a simple "on", or is PWM indicated?

    If you really want to be assiduous, you could connect both an ammeter and voltmeter to that solenoid circuit, see if drive voltage to the coil is maintained while the current drops off; pretty much positive proof that the solenoid coil, or a connection inside the trans, is intermittent.

    If you disconnect the brake switch, will the cruise-control still work properly (like, disable when brakes are applied)? Will the trans shift out of Park?
     
  11. JackC

    JackC wrench

    Joined:
    Nov 14, 2006
    Messages:
    1,376
    Likes Received:
    14
    Gender:
    Male
    Occupation:
    Retired
    Location:
    Nothern California
    Thanks for thinking of options. Should be fine. Never had a problem on the 89 and the 90 is exactly the same. They were built only 4 months apart.
     
  12. nickb2

    nickb2 Wrench. I help when I can

    Joined:
    Nov 22, 2008
    Messages:
    7,616
    Likes Received:
    109
    Gender:
    Male
    Occupation:
    Diagnostic tech
    Location:
    St-Hyacinthe, Quebec, Canada
    Sorry grand mama, but 1000$ quote jesus, no way.

    Highway robbers.
     
  13. nickb2

    nickb2 Wrench. I help when I can

    Joined:
    Nov 22, 2008
    Messages:
    7,616
    Likes Received:
    109
    Gender:
    Male
    Occupation:
    Diagnostic tech
    Location:
    St-Hyacinthe, Quebec, Canada
    Damn I wish I was closer to you guys.

    But I will be not available for a while again. Personal shyte.
     
  14. nickb2

    nickb2 Wrench. I help when I can

    Joined:
    Nov 22, 2008
    Messages:
    7,616
    Likes Received:
    109
    Gender:
    Male
    Occupation:
    Diagnostic tech
    Location:
    St-Hyacinthe, Quebec, Canada
    Jack, stick with the program.

    If the car is not worth it, let it go.

    All good things come to an end.
     
  15. JackC

    JackC wrench

    Joined:
    Nov 14, 2006
    Messages:
    1,376
    Likes Received:
    14
    Gender:
    Male
    Occupation:
    Retired
    Location:
    Nothern California
    I will still be considering that it is really just an engine miss as I think BP is suggesting with the bad tps. So, I ohmed the tps 4 times and also did a voltage range test 4 times. Test proved tps OK. Ohms where steady up and down and volts where also steady from .49 to 4.40 volts.

    Actually, this is exactly what happened to my 89. When the vehicle goes into lockup there is enough "strain" on the lower rpm engine to generate a miss. On my 89 it was simply a bad spark plug wire that I and tranny shop thought was TCC problem. Although the symptoms are not identical, I will be doing further investigation.
     
    Last edited: Aug 11, 2016

Share This Page