[MartyRay91]

Warn manual locking hubs and switch in dash engaged. Checked shafts behind wheels and their locked in as well as driveshaft from TCase. Left wheel wont engage. When first engaged yesterday after getting decent snow here in Indiana it made a loud clunking noise under driver seat at first acceleration then stopped. Seemed to be working fine till I turned down my street then it wouldn't engage. Any ideas?

 

[1999f-250superduty]

Do you have the electric shift Tcase or manual?
Is the left wheel the only one not engaging?

 

[MartyRay91]

Sorry it's an f350. But electric. I can hear it engage. I went under with everything released and all spun freely. Then I locked my hubs and switched to 4HI and heard the motor on the TCase. Everything was locked as should.(did this today)

 

[MartyRay91]

Sorry it's an f350. But electric. I can hear it engage. I went under with everything released and all spun freely. Then I locked my hubs and switched to 4HI and heard the motor on the TCase. Everything was locked as should.(did this today)

Just realized your name is f250 lol sorry about that

 

[1999f-250superduty]

Haha thats ok 🙂 so it's back working?

 

[MartyRay91]

Seems so after gunning it for a second driver side kicks in

 

[MartyRay91]

the rear that is. Front does not seem to engage at all

 

[79jasper]

Unlock the hubs, lock tcase into 4x4, now try spinning the front driveshaft.

Sent from my SM-G988U using Tapatalk

 

[MartyRay91]

I'll give that a try today when I get home thanks!

 

[MartyRay91]

Haven't gotten a chance to do that test yet. But I did have a clunking and a code came up on my reader p0720. I'm thinking maybe Tcase motor? Could that cause a clunking sound if it was failing?

 

[1999f-250superduty]

The p0720 is insufficient input from the output speed sensor. Does it clunk once or only when turning or all the time?

 

[MartyRay91]

Yeah I looked up the code. But it ties I with the Tcase motor right? And it only clunks on initial acceleration

 

[1999f-250superduty]

I'm not 100% sure but I dont think the oss is now the vss sensor I believe is but I might be wrong. If the motor isn't fully shifting into 4hi or low and then you start moving and it finishes the shift it could clunk and if that's what's happening it could be a weak shift motor or a stiff/tweaked shift fork. How many miles does your truck have?

 

[MartyRay91]

385,000. I'm getting a shift motor tomorrow just because I imagine its OE and needs it anyhow

 

[MartyRay91]

Unlock the hubs, lock tcase into 4x4, now try spinning the front driveshaft.

Sent from my SM-G988U using Tapatalk

Went under it with just the switch turned on and I can spin the drive shaft

 

[1999f-250superduty]

Ok sounds like it could be the shift motor of course with your mileage and all that isn't a big surprise tho

 

[MartyRay91]

Ok sounds like it could be the shift motor of course with your mileage and all that isn't a big surprise tho

Yeah that's what I thought too. But I try to drive and it literally drives like it's in 4x4 HI and LOW...I'm stumped

 

[1999f-250superduty]

So you can spin the front drive shaft yet it acts like it's in 4x4?

 

[MartyRay91]

Yes. I'm thinking Tcase needs rebuilt or better yet replaced. It's just odd. This truck is a trip

 

[1999f-250superduty]

It could be the contact plate in the shift motor not making good contact and it dosen't know where it is at 🤔