5.9Shaker

My trans will shift in overdrive and back out around 45 to 50 and i have noticed the tc locking up early like around 30 to 35 sometimes instead of the 40 to 50. I have seen alot of gassers do this. I know if i let if go to long it will smoke the trans. if go wot then it shifts like it should or even half throtle every thing works great but its the cruisen around town i have the problem with. Any help would be great thanks.

Fishin2Deep4U

It could be a few things.

First thing to check is the throttle cable on the trans. Make sure it has the right adjustment at full throttle.

The locking unlocking you describe sounds like electrical interference. DTT has a easy to install noise filter that stopped this issue in my trans.

A stock truck should lockup around 35-39 mph in drive. If it's locking later, you may have a different issue.

Possibility list includes APPS, voltage issues, alternator, electrical noise, solenoid in trans, PCM issue, batteries, bad grounds, and the list goes on.

Try the easy stuff first. Also, I have seen one truck that had a lock unlock issue that had a brake light switch out of adjustment. It would cycle the TC on rough rouds, but less on the hiway. It took following him to the parts shop to see the flicker and figure it out.

Dave

Carolinablue

One thing I did to mine too is put a new speed sensor in which is located on the transmission. Mine is an 01 also, but I wondering if I didn't just need to clean the old one off. You might just try this first. The sensor has a magnet in it and it picks up metal powders and flakes which can interfere with the sensor.

mr bill

Had similar problem a few weeks ago and after spending money on a new trans the problem was still there. Trans was in bad shape anyways so I got over it. They figured voltage spikes and changed alternator and problem was solved. Would have never guessed that one myself.

Dinner

For the locking and unlocking of the TC, it depends on the speed/how hard you are accelerating doesn't it? Or am I just going crazy

phox_mulder

Cheapest thing you can do is clean up the battery terminals, that will often fix the problem.

If it doesn't, clean up all the grounds, making sure they have good contact and are tight, particularly the PCM grounds.

Then move to the alternator connections, same drill.

Then if it is still doing it, do a search for foil wrap, there are a couple wires you can wrap with foil to cut out electrical noise.


phox

5.9Shaker

the issue is taking place right arend the 50 mph zone under easy consistant peddle. From what i can tell ether the overdrive or the torqe lock up is acting up and itsunlocking and relocking be for it has fully dissengaged just a 200 to 300 rpm change. And this happens really fast.

Fishin2Deep4U

Sounds like TC cycling.

IMO, under light throttle the voltage threshold to the PCM is so small, the computer can get confused. As stated, all grounds should be checked and cleaned.

You might give DTT a call and ask about the noise filter. It stopped the cycling in mine.

Dave

5.9Shaker

sounds good looks like a nice sunday project. thanks for the help

ajg617

See the thread titled trans hunting for gear in this same group. Was on page two as of this post. Foil wrap and apps reset cured the problem for me.

fordpowermuscle

Just moving the black wire with tan stripe away from the alternator worked for me...so far.

Carolinablue

Keep those battery cables and post really clean. Mine was shifting 1 to 2 and back at slow speeds and OD jumping back and forth at and around 50. Changed speed sensor and it seem to help the low speed problem but not the OD. I had cleaned my cables about 6 months ago and there was no sign of corrosion. Pulled them off anyways and saw that the post and cables had what I'd call dead lead, which is when the lead turns dark gray or black. I cleaned this off with a post and cable brush. Been 3 days nows with no problems at all. Wouldn't think that computer would be that sensitive, but I guess it is. My batteries check out good and the engine cranked fine. Just a little dead lead can cause your problems. A good cheep fix I guess. Worth a try anyways.