What would be indicated if an automatic transmission will go into low gear but fails to upshift?

When an automatic transmission is able to engage low gear but fails to upshift, it often points to issues with internal pressure regulation within the transmission system. Low governor pressure is a key factor as the governor is responsible for controlling the shift points based on vehicle speed and engine load. If the governor pressure is insufficient, it won't signal the transmission to upshift, resulting in the vehicle remaining in low gear despite the conditions that would typically cause it to shift.

This can occur due to various reasons, such as a malfunctioning governor, leaks in pressure lines, or internal wear that affects the hydraulic pressure needed for shifting. As a result, the transmission can engage lower gears but lacks the necessary pressure to facilitate a transition to higher gears.

Other factors that could impact shifting behavior include issues with clutch packs, which affect how well the transmission engages, and problems with the shift selector or throttle valve adjustments; however, in this case, low governor pressure is the primary issue that leads to the inability to upshift.