Symptoms:

• Blazer will not attempt any shifts unless I am in neutral
• Pressing 4hi, both lights flash a few times then turn off, sometimes both lights may stay on. BOTH
• Pressing 4lo, vehicle successfully shifts to 4lo
• Pressing 4lo, vehicle successfully shifts back to 2wd
• All this pertains to being in Neutral. 4hi does not work in any other gear, moving or stopped.

Should 4lo engage while in park as well, or just neutral?
I plan to jumper the diagnostic terminals tomorrow.

Any advice? Is there any adjustment I need to perform to be able to shift into 4hi as intended? (Any slow speed any gear)

Picture included of my new to me, $500 blazer