96 silverado trany

I have a 96 chevy silverado 1500 4x4 with an intermitent shifting problem. Half of the time I only have reverse and 2nd gear. The other half of the time I have full function 1st,2nd,3rd,4th, and reverse. I hooked up a scanner when the problem existed and noticed that the "b" soleniod was on all the time even in reverse. When I don't have the problem all the solenoids turn on and off through out the shift sequence. Are the solenoids fired by grounding the circuit or powering the circuit?? :banghead: Any Ideas will be appreciated

The VCM grounds the shift solenoids

The VCM grounds the shift solenoids
Thanks I think the harness sounds pretty suspicious than.