well heres my dlema. I start my truck back out of the driveway, Put the truck in drive and accaerat( sorry about the misspelling) it waits till 3000RPMS to shift to second. then the CEL lights up with a (PO720) code. the day before yesterday I was on my way home and the transmission was kicking in and out of overdrive and i got the PO720 code. I did my research and everybody said it was the vss on the tranny and the abs sensor on the rear diff. I changed both of them. well now its shifting in to overdrive and the torque converter is locking up. its been 35000 since the last tranny flush. do yall think it just needs to be tuned up? PLZ HELP!

 

how many miles are on the trans? do you have a cooler hooked up? sounds like the problem i was having with my fathers and it ended up having an issue of being to hot..
P0720 Output Speed Sensor Circuit Malfunction

 

do you smell hot transmission? Have you removed the check valve from the cooler line?

 

im not exactly sure how many miles are on the tranny but thr truck has 180,000. it does have a cooler. i replace the output speed sensor. Im not sure what the tranny should smell like when it gets hot and no i have not removed the check valve. oh and thanks for your replys

 

I would pull the check valve, and see if it isn't plugged. Mine was plugged solid, and I have fewer miles than you do...... something to look at anyway. (I got rid of mine. about four bucks in parts.)

 

if it is clogged will it make the computer throw a po720 code?

 

I think the check valve was the problem. removed it and drove it about 20 miles and no odd shifts. ran just fine.

 

Time will tell. Good luck.

 

sure will thanks again for the info. i had no idea about the check valve.

 

Make sure to post back within a week or so if the check ball delete did fix your problem, this could help a lot of others in the future with the same the dilemma you had.