What could cause a John Deere 490E to stall when hydraulics hit relief, esp with low or no voltage going to most pump sensors and weak tracking?

[Nicholas Villa]

I am looking for some help/insight on a John Deere 490E stalling issue I'm dealing with. The machine starts and idles fine, but as soon as I run any hydraulic function all the way to relief, the engine bogs hard and stalls.

Here's what I've checked so far:

• Getting 5V at the pressure and angle sensors
• Only about 0.2V at the speed sensor
• 0V at most of the other pump solenoids/sensors
• All fuses look good
• There's a steady blinking light on the computer under the seat
• The throttle has been rigged with a cable (factory control not working)

From what I've read, it feels like an electrical/control issue-maybe something with the pump controller, wiring harness, or even the ECU not sending proper signals?