Author Topic: california emissions truck engine and trans swap problem with torque converter?  (Read 305 times)

Offline 1985C10

  • Newbie
  • Posts: 4
  • Newbie
I put a rebuilt '76 350CID 2BBL in and swapped in a 1982 350THM trans, which has the the internal harness from the '85 trans in it. All was well until I tried driving it. Engine stalls immediately when putting in gear. Carb was professionally rebuilt and accellerator pump etc seem to be working fine. Otherwise, it idles and revs up just fine. Researching it appears this was a California emmissions truck and it has a "TCC" vacuum switch and other computer inputs supposedly not on all other drivetrains. Shop manual states "Transmission Converter Clutch (TCC) System - California Only". I'm thinking something is going on with the torque converter via computer because several engine/other inputs are no longer available(?) Does anyone know if there is a way to make the lock up torque converter non-computer or troubleshooting techniques to verify this is the problem? Can I simply put a regular torque converter in and just disconnect the harness to the trans? Can a pressure switch be put somewhere so it only locks up in 3rd gear? It's been awhile since on the road and just want to drive it!!! Thanx to all in advance that can hopefully help and provide some insight.

Offline 1985C10

  • Newbie
  • Posts: 4
  • Newbie
PS - original engine was 305 with quadrajet

Online zieg85

  • Carl
  • Site Supporters
  • Senior Member
  • ******
  • Posts: 6940
    • 73-87 GM squarebody extended cab and conversions up to 91 R/V series
Sounds like the torque converter is locked, almost like dumping a clutch in a stick shift
1985 C30 Custom Deluxe Ext. cab 5.7L TH400 4.56 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
https://www.facebook.com/groups/248658382003506/

Offline VileZambonie

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 17192
Just unplug it at the trans and see if the condition stops.
,                           ___ 
                         /  _ _ _\_
              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

Online Rapid Roy

  • Frequent Member
  • **
  • Posts: 465
  • Euless, Texas
Welcome
1974 Cheyenne 10 LWB 350/TH350/AC/4 BBL Quadrajet

Offline 1985C10

  • Newbie
  • Posts: 4
  • Newbie
Thanx for the warm welcome and tips. I put carb back on and unplugged harness. It did drive but seems like excessive slippage on hard acceleration. This was my Dad's truck and he took it in for recall regarding valve body in trans. Never seemed to drive right to me afterwards but he insisted wasn't trans. When I swapped harness out from original trans - it was not plugged in internally. If you walk it off from take off easy, it goes OK but if you jump on it, engine revs great but not much forward action. That's how it was with harness unplugged inside original trans, so looking to figure out remedy with harness unplugged. Can I put a standard torque converter in this computer controlled torque converter trans and will it work like it's not computer controlled? Trans has maybe 5K on it and worked fine in '82 C10 I ended up junking. Pretty sure trans is sound. If I end up having to put a "dumb" trans in I guess that's OK. Looking for easiest way out. Thanx again.

Offline VileZambonie

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 17192
I'm not really following you. To be clear, your transmission is not computer controlled. The lockup function should be but if it's disconnected it will still work as normal. The only real difference with the C is the torque converter has the advantage of being able to lock in 3rd gear which helps fuel economy and lower trans fluid temp. Leaving it unplugged isn't a big deal but it sounds like even with it unplugged you are experiencing slipping. Why don't you look into a 700R4?
,                           ___ 
                         /  _ _ _\_
              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

Offline 1985C10

  • Newbie
  • Posts: 4
  • Newbie
OK I thought there was more to it than that. Yes seems to slip under heavy load but not when accelerating slow/steady, 700R4 has been on my mind. Just something else to research etc for what's needed to complete swap(steering column? etc). I think for now I'll leave as is and try to get another project out of the way. Thanx much for following up.