At about 40mph the auto trans on my ‘01 seems to shift quickly between 3rd and 4th gear several times. The transmission shifts back and forth very fast, as if the computer can’t make up its mind whether it should be in 3rd or 4th gear. This happens in city driving after I accelerate from a traffic light. If I push the accelerator more, and gain more speed, it settles into 4th gear normally, but if I hold it to maintain about 35-40mph it starts shifting back and forth very fast between 3rd and 4th gear. Does this sound like the transmission is slipping, or is it just hunting between 3rd and 4th? Any ideas?

 

Sounds like your torque converter locking and unlocking. This is fairly common and is usually caused by noise on your electrical system. You can try cleaning both ends of all your battery cables on both sides. Clean both the cable end and where it connects to. Several of the grounds connect to painted surfaces that need to be scraped clean. If this doesn't work DTT makes a noise filter that is cheap and should fix the problem.

 

i was told that the transmission needs a program update from DC, ours is going in for it...but were we told wrong?

 

eBay # 130014599232

Apps rewire kit stops the "hunting" for a gear.

 

1. APPS reset
2. Clean all grounding wires including battery terminals
3. Check APPS voltage
4. Add ground wire to PCM
5. Have batteries and alternator tested

All can be done with little or no $

If these don't work.
6. RF Choke around ground cable to alternator
7. Ground APPS to battery
8. APPS rewire ATS has the instructions on their web site.
9. DTT noise filter

I have a DTT noise filter for sale PM me if interested.

Good luck, I did the rewire as the final solution, have done everything else with no luck.

Forgot the DC flash update.