For others following your thread--->Note: Entering the service mode is a little different on models GFWN1000, GFAN1000,GFWN1100, and GFAN1100. To enter the service mode on these models press signal, extra rinse, signal and extra rinse. Press the same button sequence to exit the service mode.
Here's the tech data sheet for your model: 31-16849 GE Front Load Washer Tech Sheet.pdf
Look on page 7 then you will see Error Code 54 that says: Motor Drive Internal Problems
Then do what it says in the next box over.
Here's the motor inverter for your model: GE WH12X10519 Inverter
Here's the control board for your model: GE WH12X10457 Control Board
Shawn has a webpage to help you narrow it down, Follow all the steps outlined in this link: GE Front Loader Washer Motor and Inverter Testing
Shawn says this: To test the motor sensor on a GE front loader washer, disconnect power to the washer then access the control. Follow these instructions to access the main control.
1. Remove the soap dispenser to access the hidden screw and remove the screw. 2. Remove the top of the washer. 3. Remove the two screws that hold the control on under the top. 4. Press in on the clips on the back of the control panel to release it.
Once you have accessed the control, locate the P9 connector and disconnect it. On that connector there will be two yellow wires. These are the two wires that go to the sensor. Test continuity across these two wires and you should get approximately 118 ohms. If not, the sensor is bad. The motor will have to be replaced if the sensor is bad.
Here's the motor for your model you can order if needed:
GE WH20X10028 Motor Asm Kit
Let us know what you find.