First off, let me thank you for providing all the information you did. If you get used to doing that when you are hunting for solutions you will have it much easier.
Here is the book definition:
DTC 47/P1776 sets when Low-Reverse solenoid switch valve pressure is high for second time.
Internal trans-axle failure may exist including sticking solenoid valve or solenoid and pressure switch failure.
Here is the test process:
Disconnect solenoid and pressure switch harness connector. See Figure 1.
Measure resistance between solenoid and pressure switch terminals No. 4 and No. 6.
See Figure 2.
If resistance is not one ohm at 68 F (20 C), replace solenoid and pressure switch assembly.
IF the sensor tests good then you will need to test the actual pressures in the hydraulic system. But as you are not seeing other pressure related codes it is probably the sensor in the solenoid.
Images (Click to enlarge)
Thursday, January 26th, 2017 AT 4:05 PM