What does it mean when the o/d off light flashes & the o/d doesnt work at all? on 1994 Toyota 4Runner

I have a 94 4runner 4wd automatic v.6 & recently installed a tranny/transfercase from a 95 4runner 4wd automatic when taking out mine from the 94 the tranny was a 95 so i new it would be compatiable also b4 installing the 95 i made sure it worked after installing everything seemed to work all the gears worked except when taking off in drive its as though its in 3rd so i manually shift starting in L then 2nd then Drive would that be a selonoid?

Asked by for the 1994 Toyota 4Runner
This means you have a problem with the transmission. You can take it to a shop and have the codes scanned (I think Autozone does this for free), or just go out and buy a decent OBDII scan tool and do it yourself (it is really easy). Armed with the trouble codes, you may be able to narrow it down. I have a 2000 Ford Windstar that had the same problem. The O/D OFF light would flash after the transmission would refuse to shift from 1st gear to 2nd gear when cold. I pulled the codes and discovered that the OSS (Output Shaft Speed) Sensor signal was intermittent. I replaced the sensor and have had no problems since.