4lo will not engage but 4hi and auto 4wd will

[2002 Chevy Avalanche]

I put the truck in neutral, like you should, i bring the truck to a stop, and i push the 4lo button. It flashes for about 5-10 secs but then goes right back to 2hi, I've tried rolling about 2-3mph and it still won't even engage. Its a 2002 chevy avalanche z71, with the 5.3L V8. Sometimes when i press it, it engages no problem, but other times, it just flashes and goes right back to 2hi. When i press 4hi, it goes right in, but 4lo is giving me some problems.

[Brian715]

Sounds like what the truck is supposed to do if the truck is not in neutral. Maybe whatever tells the t-case that the truck is in neutral and it's ok to shift into lo is not sending the signal.  

[Brian715]

https://www.truckmodcentral.com/threads/strange-4-low-no-shift-problem.29694/

Check out this thread. 

[2002 Chevy Avalanche]

Thanks man will try to check that out

[SunShine01]

Was this fixed ?

 

I got the same truck and same issue.

 

Mine ended up being a wire to the tranny.

 

What I noticed was the shift indicator was not illuminating and when not illuminating wouldn’t go into low.

 

Swamp was my culprit.

 

Respliced the wire and it’s fixed for now.

 

 

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