1st gear/Drive issue?

[fletcher969]

1999 3.0
140K
4R44E (4-speed)

I don't have direct access to the transmission in question, because I'm only considering a purchase of the truck above, but it seems like a good deal except for the ONLY issue the current owner says it has. It appears 1st gear doesn't work/engage if the lever is in the "D" position (revs up, but goes nowhere), but works fine if it's in the "1" position. All other gears work including reverse. There is no slipping, no hard shifts, no noises or smells. For all intents and purposes, everything works perfectly except it won't start from a stop in Drive.

My question is...what are the most likely causes of this scenario?

Thank you.

 

[fletcher969]

From some reading I've been doing, I may be describing the problem wrong, and I may have missed something.

1st is available in the L/1 position, 2nd in the 2 position, and every gear including OD works in drive except whatever gear Drive likes to start in normally. Reverse works fine also. I've been assuming 1st gear is the gear Drive normally uses for starts, but if Drive normally starts with 2nd gear, then that's the gear which isn't working in Drive. Again though, 2nd is available in the 2 position.

Anybody?

Thanks.

 

[fletcher969]

The one-way (sprag) clutch has likely failed, thus allowing manual 1st/low to work, but not 1st/low in Drive.

Now, with that nailed down, my question is this:

Is there a way to mitigate the situation (i.e. avoid using LowDrive at all costs) for an extended period of time, or is a failure of the tranny imminent, and unavoidable?