Here is a Razor Ground Force version 13+ wiring diagram with directions for testing the throttle and controller. The directions are in green boxes on the wiring diagram.
These controller and throttle testing directions assume that the battery pack has been load tested and does not drop to less than 23 Volts when under load, and that the brake lever switch, power switch, fuse, wiring harness, and motor are good.
Please let us know how it goes.
Since the battery pack is not dropping under 23 Volts while it is under load that points towards it being good and not causing the problem.
Your test results indicate that the controller is outputting power to the throttle, and that the throttle is working (0.8V through 3.5V is a normal output for a throttle). This points towards the controller being faulty. A faulty controller usually still provides power to the throttle, but not to the motor.
Before replacing the controller I would disconnect the brake lever switch connector from the controller to make sure it is not causing the problem. Often times a brake lever switch will fail and lock into the on position which tells the controller to turn off the motor.
Some of the newest model Razor vehicles have normally closed brake switches. I am not aware that the newest Ground Force go karts do but just in case it would be a good idea to jump the controller's brake switch leads together to simulate a normally closed brake switch. This way the controller's brake switch connector has been tested in the open and closed positions to eliminate any chance that the brake switch is causing the problem.
If the kart still does not run with the controller's brake switch connector in the open and closed positions then that points towards a faulty controller. We sell a lot of controllers for Razor Ground Force go karts so they are a part with a high failure rate.
Most people just take a guess and throw new parts at their Razor go karts hoping they will solve the problem, and you have thoroughly tested the parts and can now make an educated decision as to which one to replace.
Please let us know if you have any questions.
My Razor GF v 13+ does not run. The batteries and motor check out and all the power wires from the controller are good. However, I am trying to figure out how to fully test the controller/throttle so i can isolate what I need to replace.