Manufacturer specific code.

P1780 - Transmission Control Switch

That code refers to the neutral safety switch circuit, but you must understand diagnostic fault codes never say to replace parts. They only indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition. When a part is referenced in a fault code, it is actually the cause of that code about half of the time.

If your mechanic already diagnosed this problem and determined the switch must be replaced, you already paid for the most expensive part of the repair so it does not make sense to not let him finish the job by replacing it, checking for proper operation, and erasing the code. If he only told you the fault code and guessed the switch was the likely suspect, you have a 50 percent chance of wasting your money on an unneeded part. We normally check for stretched and corroded connector terminals, and grounded or cut wires first. When no problem is found there, a few quick voltage measurements will indicate if the switch is defective.