LBZ: No Reverse

[Vrabel]

Parked last night with no issues. It was sub zero wind chill last night and is about 10 in the sun now.
Started up ands been running for about 20 min. When I shift to reverse, the indicator just flashes. No problem with forward gears, just now reverse.
What could cause this?

 

[Vrabel]

running / warming up for an hr now. still nothing

 

[Mike L.]

Scan it and watch speed sensors. Turbine and output speed sensors better be reading 0 rpm at standstill.

 

[Vrabel]

well, I turned it off and restarted. Went no problem. I cant read codes right now (Scanner 1/2 hr away).