OBD2 code P0740 -- torque converter clutch.

Obd2 code p0740 -- torque converter clutch circuit open

Hey all,

My Tahoe has had this error code ever since we had it rebuilt this past summer (2012). I pulled and installed the tranny myself to save on money, as my father-in-law has numerous connections when it comes to parts and repairs. Aside from minor damage to a port on the neutral safety switch (pnp switch), the install was uneventful. I've since replaced the switch so the plug fits nice and snug. I've read and erased the code numerous times to no avail, hoping that it was an old code stored from before the rebuild. It should be noted also that we replaced a faulty catalytic converter including the entire y-pipe prior to the transmission malfunctioning. As a matter of fact, I believe the faulty cat led to the transmission problem although I'm not sure. Anyways, I've read this ident and troubleshoot page here:

http://repairpal.com/OBD-II-Code-P0740

It says that in some cases, there may be performance problems, such as dying when coming to a stop after driving on the freeway and/or misfire-like symptoms.

This has happened two or three times at (unbelievably) the same stop light on the far side of a freeway overpass. It also says in unusual cases, there are no adverse conditions noticed by the driver. Aside from the few times its died, it shifts regularly, on time, and seemingly with the proper rpm drop with a steady acceleration, including overdrive. Also, when I press the brake, there is a noticeable click from under the dash. I've heard that a brake switch may be the culprit and am curious if a click is good or bad :)

The code reader we bought from harbor freight doesn't include the freeze frame data needed for further diagnosis, and I'm wondering if there are any glaring problems I should be aware of before we take it to the Aamco up the street. I'm fairly handy and aside from pulling apart the tranny itself, I'm hopeful that there may be a fix for this or at least a better direction to face or some kind of information I can arm myself with when taking our to the shop in that scenario. Please help.