Aloha all,

I have a mystery I was hoping I could get some help solving. I just picked up a gorgeous 2003 neon with 60k miles on it at auction. It threw codes p0700 and an invalid skim key code. It wouldn't shift past 3rd gear and would jerk violently what seemed to be randomly. I started with replacing the transmission solenoid, which we picked up at the junk yard. After switching out the part, the codes were cleared and check engine light went off (maybe due to disconnecting the negative battery terminal). The car drove awesome and I got it home (20+ miles away) with not a single issue. Of course this is not the end of the story... the next day it jerked violently on my wife which she said felt like when she was trying to learn to drive standard. So I moved on to replacing the transmission filter (no metal shards at all in pan) and all new tranny fluid. The car would still jerk about once a trip, then run awesome the rest of the time, shifting super smooth all up and down the range. So I tried the in/out speed sensors, still no luck. I did notice the jerk isn't random, the first time I accelerate up to about 35 mph and just about 2-3 seconds after it settles into gear it feels like the transmission locks up or shifts straight to first and it'll buck good, drop about 5 mph, then it shifts right into the correct gear and off I go as if nothing ever happened. No check engine light, and usually once it goes through the little dance routine, it won't do it again until the next trip. Any suggestions would be well worth it, and I'll keep y'all updated on any attempts/progress.

 

Did you ever find out what was happening?

 

Replaced transmission fluid and filter. Problem persisted, replaced speed sensors. Car went back into a limp mode and engine light returned with p0700. After scanning the TCM it shot a p0765 and p1684. We put the solenoid into learn mode with a buddy's SolusPro snap-on (same scanner we used on the TCM), then it seemed to drive fine, codes cleared. Once cold again it immediately bucked on the next test drive, then after idling for a few mins in park on the next drive the engine light came back on and it bucked again, this time with brake applied at a full stop in drive. I ditched the old solenoid for credit at the junkyard and installed a new solenoid from autoparts store. Still, the problem persisted, this time under different conditions, sometimes a lower speed. I traded the car with a mechanic friend for a year older dodge neon SE with 70k and let hime take the SXT since he has the time to put in on this baby. I'll let ya'll know when/if he tracks 'er down.