91 240sx (AT) will not shift to 4th gear (overdrive light stays on)

[vacnsewmedic]

I hope im in the right forum,,,,,,but I have been running in circles trying to fix this problem.....

EVERYTHING, is fine

shifts to 1,2, and 3rd fine, just not to 4th.......and overdrive stays lit up once the key is turned,,,,,no blinking,

please. please ifns ya got an idea please help me

[The Mic]

I think the reason is one of two things. One could be that you are losing pressure in the direct pressure area in the 4th gear. Or you could be losing pressure when the fluid gets warm or hot. Either way, looks like it's going to be a trip to the transmission shop.

[vacnsewmedic]

what if Im not getting battery voltage to my od switch,,would this mean its not getting circuit to make the transition to 4th gear?

i think it might be electrical........no self diag works.....light just stays on...no blinking....

Have u heard of this prob before?