Neutral safety switch location

If there are no codes then I suspect it is a connection issue or some other electrical issue. This could be a TCM but normally when a module fails there are codes that go along with it. I would remove the connectors on the sides of the transmission and make sure there is no water or corrosion in them. You should have the TCM on the passenger side and the NSBU on the driver side. These have both been known to cause this warning. There are a lot of forums on all this, not that I listen to many people on forums because there are not many answers. Let us know if there is anything in the connectors and once they are connected back to the transmission, just test operation again and make sure it wasn't a loose connector.

I am assuming the starter will not crank the engine. Look for the 10-amp "crank" fuse number eight on the left side of the instrument panel. It will have two test points on top. Check for twelve volts on both of them. You should find twelve volts when the ignition switch is in the "crank" position. If you find that, remove the starter relay from its socket under the hood.

Be careful to not poke your meter's test probe into those terminals. Doing so could spread them and cause future intermittent connections.

One of those four terminals must have twelve volts all the time. Disregard that one. Two others should read very low resistance to ground. As an alternative, move your meter's or test light's ground wire to the battery's positive post, then use the positive probe to search for a good ground. Two terminals in that socket will show twelve volts now, or low resistance to ground. Disregard those two terminals.

That leaves you with just one terminal left to check. That one should have twelve volts when the ignition switch is in the "crank" position, just like fuse number eight did. If you do not find that switched twelve volts, the neutral safety switch and its wiring are suspect. To bypass the neutral safety switch, it is on the left side of the transmission. Unplug it, then in the connector, jump the purple and yellow wires together. If that switch is defective, the starter will crank now, including when in "drive" or "reverse", so be careful.

Hell, I'm Danny.

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Danny-

In case you don't have wiring info.