tcase tied to speed sensors???

I am looking at a 2000 crew cab long bed with the 7.3. it has the 4r100 and ESOF tcase, the truck will go into 4hi but not 4lo.. dude selling says that a speed sensor is bad and that is what the problem is.. he said that the vss, trans input,trans ouput, and tcase speed sensors are all tied together to work together and that's why it wont go into 4lo.. any input on this.. thanks..

He's fos.

So I've read..and it could be relays, or vacuum switches, tcase motor..he said dash light comes on for 4hi but not 4lo

Possibilities include a worn t-case, bad shift motor, wiring failure, which covers the relay.
Vacuum is just for the automatic hubs.
There maybe some other cause, but those are the main failures. All the other sensors are tied to the pcm for different things, but not for the esof.

Ok..I'm just looking into trading my zf6 7.3 for this truck..wanna make sure of what I'm getting into..I don't wanna trade a truck I just put money into for a turd..only reason I'm considering is for the crew cab..I currently have ano extended cab

Did you have your foot on the brake and in P or N while shifting into 4lo?

Foot on the brake I don't remember..park and neutral yes

Foot has to be on the brake to go into 4lo.

Truck running.in park, foot on brake no 4lo.in neutral foot on brake no 4lo

If the light for 4low doesn't come on when you first turn the key, it's a wiring fault. Not sure on the 2000 but my 02 had relays behind the cluster as well as under the hood. Sometimes the esof motors can bind or get sticky or the circuits for the position indicator can be bad. IMO it's easy enough to just swap the esof tcase for a manual one.

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Have you pulled the codes yet? There probably is one for this...

A shift motor is like 45$. Unless you know someone with a known good one for a tester.