Why won't my Volvo A35C shift in high range?

[Frank Zimmerman]

I'm having a transmission issue with my Volvo A35C articulated dump truck. In low range, it shifts through all the gears

 

[Paul Adrian]

Hi, @Frank Zimmerman, I'd start by checking the transmission fluid level and condition, then inspect the high-range solenoid, wiring, and any fault codes. A pressure test can also help determine if it's a control issue or an internal transmission problem.