Engine/Transmission (1998.5 - 2002) Possible transmission problem

[PLaFrombois]

I'll try and be as specific as possible to explain what's happening. I've changed the transmission filter and fluid in the pan 3 weeks ago. Fluid level is where it's supposed to be on the dip stick. When I drive with O/D off between 25-35 mph and the accelerator is held steady the transmission seems to be searching for a gear. I can manually shift to 2nd and it's fine. Transmission temps are taken in the pan. These range from 120-130, and up to 140 if it's a lot of stop and go traffic. When I get up to hwy speeds, 50-65 mph it seems to be hesitating. I've noticed that every once in a while I'll see the tach needle move a little even though the speedometer doesn't move. The fuel pressure is fine, and no lp problems. Fuel filter has a little less than 8,000 miles. I just picked up another fuel filter and will change it in the a. m.

Thank you for your help.

Paul

 

[BillGotthelf]

When you deselect or turn off overdrive the trans will attempt to lockup 3rd gear under light throttle at the speeds you quoted. Do a search on lockup hunting and you will see the problem-electrical interference from the ecm/pcm to trans. check out www.happibox.com

 

[Strick-9]

It sounds like the torque converter is locking and unlocking.



By pulling it down into 2nd, you prevent TC lockup and thus the problem seems to go away.



With OD off the converter will lockup in the 28-32 mph range (your problem area)



With OD on, the converter will lock up at 45--50 mph. (Your other problem area)



Search the archives for more information on TC lockup.



For some people a simple cleaning of the battery terminals helps. Disconnecting the batteries for 30 minutes will usually cause the problem to go away for a few days. Others pull the TPS wires out from the wiring harness to minimize electrical noise. On some trucks, none of this solves the problem. It's been discussed many times and you should be able to find tons of information about it.



Good luck,

Chris

 

[stevek]

Just curious but what does the locking/unlocking feel like? Can you see the RPMs change on the tach?

 

[BillGotthelf]

If you have alot of electrical interference it feels as if the TC is slipping. If you are cruising at say 65 and your rpms are at 1900 and you accelerate you will notice about 100 rpm increase as you begin to accelerate. Also the TC hunts around for overdrive lockup over 45 mph. It doesn't seem to want to lockup until you get over 55.