I would run, not walk away from that stealer, unless they've gone through the complete troubleshooting list. If everything BUT the TCC is woking normally, I think I check that electrical circuit and solenoid/switch valve first. My first impression would be (if they haven't).....another ripoff specialist. Notice how they zeroed in on the last item? Did they tell you they went through all the ts steps indicated in the shop manual? Did they eliminate all other potential causes? I seriously doubt it. For sure, I'd get a second, and maybe third opinion before I did anything. It won't hurt anything, except maybe fuel economy with it not working, unless there is something coming apart internally. May want to do a fluid/filters change first, to see if there is anything abnormal in the pan and/or on the pan magnet. Here's what the FSM says are the likely causes of P0740:
RELATED DTC P0750 PRESENT
TCC SWITCH VALVE STUCK
TCC REGULATOR VALVE STUCK
INPUT SHAFT SEAL RING CUT
TORQUE CONVERTER AND/OR INTERNAL TRANSMISSION
Please keep us posted on what you find out.
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