1999 G16E stopped while driving

[NewCartGuy1999]

I bought this cart from old couple. Wife was driving and it quit. I have the schematic and have started trouble shooting. Batteries need replaced but still have between 35-36 volts, so keeping them hooked up until I diagnose the issue. Checked and replaced speed sensor/throttle control. Checked button on "go" pedal is functioning properly. Went to check voltage through key switch and only got 16v. I had black meter lead on negative battery terminal. Also only had 16v to solenoid. What am I missing?