PO742 GM 4T65E Tranny Code

[Ryan00TJ]

Mother's 98 Monte Carlo Z34 got this code a few days ago and the car is hardly driveable. Upon startup it bucks and stalls and shakes. The code revealed to me was PO742.....Torque converter clutch circuit stuck on......

What does this mean? Sounds like the torque converter is stuck locked. Does the transmission need rebuilt or is it simply a solenoid gone bad not allowing the converter to unlock?

Thanks for any help!!!

 

[brianl703]

It sounds like there's an electrical problem causing the torque convertor circuit to be on when it shouldn't be.

An external short in the harness could cause this.

I'd start by checking the torque convertor circuit for the presence of voltage with the key on, engine not running. If there's voltage there, either the PCM is bad or there's a short somewhere.

 

[brianl703]

GM Techlink says to replace the TCC PWM solenoid for 2001-2003 cars. I don't know if that applies to 1998 cars, but I guess it would (maybe 2001-2003 cars had more issues with the TCC PWM solenoid).

See this:

http://www.gmtechlink.com/images/issues/apr04/TLApr04e.html