code 1742 is a variation of the 743 code and referring to the same problem.
Unless you take it slow and get all the info before acting, you may not have 'good' success as well as spend money over what is needed.
Normally, the solenoid circuit can be tested from outside the trans before taking anythig part, then proceed accordingly.
For this you need a dealer test set or at least lead and contact info for a standard multi meter test.
The PCM knows the TCC circuit is in trouble by inductive signitures when it operates and releases, test for opens, grounds and shorts to other power either in or out outside the trans.
The failure is reported by these codes but it can't tell you exactly where the physical/electrical fault is. (wiring, solenoid etc.) just specifies it as the TCC 'circuit'.
As far as the TCC operation, you should see the operational fault in cruise especially if the truck has a tach.
If the TCC doesnot lock, the rpm will rise and fall quickly by several hundred rpm with light throttle applicatations on and off, indicating the converter is not locked. If locked, the tach won't move fast but will rise slower in conjunction with road speed.
The TCC is normally modulated more than most think. The application of the brakes even lightly or momentary during cruising will unlock the converter a second or so then locks it up again as a normal operation.
Last edited by Bluegrass; 03-14-2007 at 02:45 PM.