Just back into Hummer ownership with 08 H3. H2 for years, sure wish I'd kept that one. Anyway, driving this 08 h3 home it wouldn't stay in 4H unlock. I nursed it home in 4H lock, read some old forums and went straight to replacing the plastic fork with metal one in TC. The plastic looked ok but replaced anyway. All back together and it still won't stay in 4H. All shifts fine, bit as soon as let off accelerator it's like it kicks out of gear. I have to stop, turn it off, turn it back on. Previous owner said he never used buttons and I didn't notice what was even on when I picked it up. He did say he replaced front tires but same size as back. Any help out there what to look for next.

 

Let me add that 4H lock and 4L lock work fine. Just won't stay in 4H for highway driving

 

Possible dirty switches on center stack or actuator **** the bed.

 

our H3 would not go back to 4 high, evey month i run the h3 thro the 4 wheeler drive modes and craw over some parking curbs and return it to 4 high, it wouldn’t so so i did some checking and the shift actuator was bad, so i had it replaced, no problems since…..

 

It appears the BW4493/4 is failing, try a new 89059551 first?