Transmission Issues

[Marsr]

While driving around 15-20 miles an hour the rear end trany locks up like I am braking, when I slow down it starts rolling again until i speed up to around 20mph then it locks up again, if I select 1st or 2nd gear it stops completely, reverse is ok. Anyone have any ideas what can be the issue?

 

[ecqm8000]

You said 15-20 it locks up. When you select 1st or 2nd it does not. 2nd gear will allow higher speeds, does it try to lock up in 2nd over 20 mph? If not, is the trans trying to shift to third (part throttle) at the 15-20 mph speed? That might idicate an issue in the trans trying to be in two gears at once. I'm not a tranny guy and am not sure it's even possible in an auto.....

 

[Marsr]

2001 eb 5.4l

2WD E40D Transmission is bad causing this issue, I was told by my technician that a 2002 or newer tranny wont work on the 2001 Exp it would have to be a 2001 used or rebuilt trans, I dont know what is differant with the 2001 model the original only has 55k miles, an I had the LSD replaced under warranty no heavy usage on trans or rear end. I pull a light boat a couple times a year, pretty bad to only have 55k and no signs of trouble before it just locked up.

 

[tmajikman]

Change the fluid and filter and see if that fixes it.

 

[Marsr]

Had to get the tranny rebuilt to fix this issue.