When you shift into reverse does the R illuminate on the dash or on the console? If it does not, then what you could be experiencing is a transmission range sensor that could've gone bad. The sensor is located on the topside of the valve body; however, it can only be serviced by removing the valve body itself.
I have attached a schematic for the power supply of the module that corresponds with the sensor as well as the location of the sensor and the plug for further diagnostics.
What you should do is unplug the switch and verify that there are no terminals that have any corrosion or damage. Then you can start checking the wires back to the PCM for continuity to ensure that there are not any breaks.
Let us know what you find,
Images (Click to enlarge)
Sunday, January 29th, 2023 AT 7:57 AM