When driving at 45 to 50 the truck jerks and shifts in and out of OD. (when the OD is not turned off) Ive read alot of tranny topics but im not sure where I should start looking for the problem. TPS, TC or just rebuild the whole tranny. The truck is all stock except for the custom 4" dual exhust with 305,000 Miles. Also Ive heard that if your speed is under 50 you should always drive with the OD turned off. Is this true? Thank you for any help you guys can give me.

 

If you haven't already, I'd start with a fluid and filter change.<br>Then make sure the linkage is tight and correct.<br>Does it work correctly in 1,2 and 3?

 

I agree with the foluid change. Next, check the TPS. I think that is probably the culprit.<br>george

 

One of the tricks to making the 47RH automatic live is to keep the RPM's up. The more load, the more revs needed. Around town and unloaded you can drive like an old lady and I don't think it would make any difference. <br> Tony

 

The fluid and filter were changed about 3,000 miles ago. That was the first thing that came to my mind also.

 

The tranny has a good firm shift in 1 2 and 3. But if you want it to shift in OD the Tach has to be less than 2 grand and your speed must be over 50. Its a big pain in the butt.

 

I think that is the way it is supposed to work...except that your TPS may be dirty causing the signal to be jumpy right at the point where it allows OD and lockup at 48 to 50 mph. This is causing it to go in and out. Try squirting some CRC contact cleaner in it along the input shaft and exercising it. They can be taken apart and cleaned but you then have to figure a way to put it back together after drilling out the rivets. Some people have also said that a noisy signal can be cured by removing the wires from the loom to get them away from other wires which cause interference.