99 Blazer Torque Converter

crashomaticcrashomatic Member Posts: 2
edited March 2014 in Chevrolet
We're working on a 99 Blazer and the torque converter has an issue locking up.

At speeds between 40mph - 50mph and under medium load (i.e. going up medium incline) it seems to lock/unlock, lock/unlock.

WE replaced the tranny filter, added new fluid and the TCC solenoid.

What's next?


  • repairdogrepairdog Member Posts: 948
    Theres a soleniod that controls that but I have to ask if you are sure its converter and not 3-4 shift as they feel almost the same so drop it in 3 and then D and see the diff and then the final rpm drop as converter locks. Possible bad throttle position sensor (TPS) on the throttle body that the PCM uses the input for throttle pos to signal load and shifts with the trans inputs.
  • crashomaticcrashomatic Member Posts: 2
    It's when the car is in 'D'. Drop it to 3 and everything is fine.

    So the TPS might be bad which is not giving the right read on whether the torque converter should be locked or not?

    We drove it with a computer hooked up and the computer is saying it's locked, but it's bouncing from locked to unlocked.

    Still think it's TPS?

    Why would there be no code?
  • repairdogrepairdog Member Posts: 948
    Just a cheap potentimeter or resistor that gets dead spots and gets non-linear so for $25 easy to rule out and simple to change.
  • murphy51murphy51 Member Posts: 5
    My 99 blazer 4x4 shows a p1870 fault code,but yet it shifts fine and shows no sign of slip while driving.Is it a big job to change the tcc solenoid?How much do they cost and what would a shop charge to replace it?
    Thanks for the help.
  • kjames0189kjames0189 Member Posts: 3
    I have a 2000 Chevy Blazer it started having trouble when I would put it in drive or reverse - it didn't want to go into gear. When driving home the second gear drum burnt out. I took it what I thought was a mechanic with a great reputation. He was supposed to overhaul the transmission. I've had to take it back to him 3 times and I'm getting ready to take it back for a fourth time. It acts like it isn't sure when to shift, it will wind the gear out then the RPMs will shoot up then finally shift. Some times it doesn't seem like it is ever going to shift. The blazer has problems pulling hills and again is having trouble going into drive & reverse. You have to shift it back to nuetral then put it into gear.

    Are there any possible items that the mechanic may have fogotten to replace? He says that he's replaced all the components in the transmission as well as the value body. I'm beginning to think he's short cutting something because it doesn't really drive much different than it did when second gear fried. I've only been able to make it a couple of weeks each time he works on it.

    I'm sort of stuck now, as much as I have invested. I thought that if I possibly asked some direct questions I might be able get the thing fixed.

    Any advice is appricated.

    Thank you.
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