Neutral safety switch?

What are you trying to do? The simple and fast answer is "no". Your vehicle uses a "transmission range sensor" with nine wires. The wiring diagram does not show if there are multiple on/off switches in the unit for the various gears or if it uses a variable resistor, similar to a throttle position sensor. They show two "B-Y" wires that are connected together in "park" and "neutral" by the range sensor. One of those wires puts twelve volts onto a terminal for the engine computer labeled "STA" which is probably for the starter circuit, but I am not sure I am ready to make that assumption. Beyond that the online service manual site will not let me continue so the rest of my wondrous description is generic for most car models.

The engine computer and/or transmission computer wants to see voltage switching on and off on the various terminals to know which gear you have shifted to. When you have voltage appearing on a wire when it should not be there, or it is not there when it should be, the computer becomes confused, then goes into some type of default mode where it does not respond the way you are expecting it to. If you are working on a no-crank problem and you want to bypass the range sensor, it appears you would need to jump the two "B-Y" wires together, but then comes the problem. If you left that jumper in place on older cars, you would be able to start the engine in gear, which is a safety problem, but it would not affect operation of the engine or transmission. With the computer controls on your vehicle, if you shift to any other gear without first removing the jumper, that would confuse the computer because it is not a normal state. It could look like it's in "park" and "reverse" at the same time, for example.

If you get the engine started, then remove the jumper wire first, then shift to reverse, the computer would see the open circuit, (switch turned off), when you were still in "park", and that would confuse it. The only way to avoid a conflict would be to pull off the jumper wire just as you shifted to another gear, but when you shift to "drive", you have to go through "neutral" to get there, and you would have to put the jumper wire back on for a fraction of a second.

Can you see how that would be almost impossible? All this switching takes place at the right times as you move the shift lever, with no gaps or overlaps. When that does not occur exactly at the correct times, the computer is going to do something undesired.

The good news is there are two clues you can look for related to the range sensor. If there is a problem with when or if one of the internal switches changes state, and you have "PRNDL" letters on the instrument cluster that light up one at a time, it is common on many models that all the letters will light up at the same time, indicating a problem has been detected. If only one letter lights up at a time, and they all work at the proper times, it is pretty likely the range sensor is working properly. When the "P" lights up, the engine computer should allow the starter system to work.

The second clue is range sensors commonly cause problems intermittently before the defect becomes permanent. Try shifting through all the gears a few times, then try cranking the engine. For sensors that have multiple internal switches, doing that turns them on and off multiple times, and that can get a switch with pitted or arced contacts working again for a little while. If your sensor uses a "potentiometer", like a throttle position sensor, those send a variable voltage signal to the computer, and the movable contact can become weak and make poor contact or it can get a tiny chip of carbon stuck under that contact. Exercising the sensor a few times can work that chip out or help the movable contact to make a better connection temporarily.

If this does work, there is still likely to be some incorrect switching during this procedure, and to get past that, you might have to shift back to "park", then turn the ignition switch off to reset the computer, then turn it back on and try cranking the engine.

Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.

Your ignition switch has numerous individual switches built in. One of them is for the starter circuit. How are you going to handle all the others? One switch supplies power to the power windows, heater fan, wipers, and other accessories that only run when the ignition switch is in the "run" position. Another switch provides power to the systems that work in the "accessory" position, such as the radio. There is another switch that grounds the "brake" warning lamp in the "crank" position as a bulb test.

You can add a single switch to run the starter, but you would still have to turn on the regular ignition switch. Doing that would bypass the neutral safety function which is built into the engine computer. It is that computer that turns on the starter circuit, and it is not going to do that until it sees the ignition switch has gone through the proper sequence of positions. Here is the starter wiring so you can see how the system works

P1780 - Transmission Control Switch

Actually, diagnostic fault codes never say to replace parts or that one is bad. They only indicate the circuit or system that needs further diagnosis. In this case the switch could be bad, but there's an equal chance there's a problem with the wiring. We look for broken and bare wires first, then do a few voltage tests before settling on the part.

Your code listing might be more descriptive, but this one that I have doesn't point to the neutral safety switch. It depends on the terminology that is used.