I had an accident with my '03 Neon SXT automatic on the front left side. I changed out the cam sensor and trans output sensor based on codes. Got the new bumper on, new bulbs, tire, wheel, etc...and thought everything was good to go. Now it's shifting hard from first to second about 10% of the time, and sometimes not shifting out of whatever gear it starts in (another 10% of the time) BUT it will still go into reverse! Rest of the time it's fine. When it won't shift it throws codes and won't allow me to change gears unless I shut the car down. I'm getting errors P0700, P0731, an P0736. Since I just replaced the trans output sensor I can only assume that either I got a faulty trans output sensor or the socket for the sensor was damaged in the accident, there's something going on with my transmission fluid (dirty or something of that nature, something going on with the trans input sensor, or something else outside of my knowledge level like the computer needs to be reset or something of that nature. All I have to do to get it to reset is turn off the engine and re-start it. Problem "solved". TOTALLY lost. Have a newborn so would rather not guess and change parts one at a time and waste money frivolously as you can imagine. A little help from more mechanically inclined people would be most appreciated. Thanks in advance!

Check out the Second Gen section over at www.neons.org

http://forums.neons.org/viewtopic.php?f=40&t=335484

Wiring and TCM are located at left front of vehicle down on lower radiator support, right were the damage was correct?? Wiring problem from TCM to trans or TCM got wacked and has internal problems. Check your wiring!!!!

Any chance it could be the shift solenoid? It's just behind (when looking from front to back of vehicle) the trans output sensor that I had an issue with, and on same side. Looked at all the wiring and it's all looks good. Couldn't check for cuts from trans to TCM without removing the protective housing, but nothing looks like it got pinched or anything as the housing wasn't cracked or broken. Would the stealership be able to plug this into a computer and tell me EXACTLY what the issue is so I can fix it myself?

Did you look up the fault codes?

The delearship is going to get the same codes and offer to fix the car for you, not to mention sell you the parts.

Check the solenoid pack connection located between the speed sensors. Look closely for any damaged wiring as another member posted. A cut wire can really cause havoc. Does not sound like a speed sensor issue which normally puts the trans right into limp mode (2nd gear only), also the speedo would not work.

Throwing codes P0700, P0736, and P0731. P0700 trans control system, P0736 reverse incorrect ratio, P0731 gear 1 ratio incorrect. Kinda what I figured re the output/input sensor...would go straight into limp mode and no speedo like before...fixed that already. Would rather know what the issue is based on these codes, and fix myself. If I have to I'll take it to them if their equipment is capable of telling me exactly what is wrong and then I'll fix it.

Anyone?

I suggest you pick up a used PCM at the salvage yard from the same year/trans Neon, and see if that changes anything. For $35-$40, it's worth a shot, and since the hit was right where the PCM is located, it may have sustained interior damage.

check the grounds going to both input and output sensors....They share the same ground...if they are worn ,cracked or broken..this will cause incorrect shift errors..very common with the 604 transaxle..

my intrepid threw the p0700 code. I had to replace the valve body. There are those that say cleaning the solenoid pack will fix it. I went the pop and swap route because of time constraints, but this may work. you just hafta make sure you put it back together exactly the way you took it apart.

Transmissions ( Electronic types especially) are not rocket science.
BUT, they can be very intimidating.

That said,,, if your not comfortable digging into the electrical side of it, my best advise is please don't just throw parts at it. Find someone who is familair with the TCM based Chrysler transmissions. Chances are you will ultimatly spend less time, money and frustration in the long run.

There are a multitude of things that can and will cause very similar shift complaints. Thus why you can and will get ( fill in the blank ) fixed my problem type of replies.

Ok, now that thats out of the way and should you decide to dig into it yourself.
My advise is ck wiring . Having been involved in an accident sort of rules out sensor and or internal trans mechanical issues

P0700 is nothing more than a PCM code to turn on the ck engine light alerting the owner there is a code in the TCM

P0731 is just a code to show the gear ratio error occured in 1st gear

P0736 is just the code to show the gear ratio error occured in reverse

As a result of a gear ratio error the trans controller turns off the eatx relay which is what supplies B+ voltage to the trans solenoid pack.

When this happens the trans resorts to limp in mode ( 2nd gear)
2nd is capable because thats where the manual valve is positioned in the valve body thus it allows a non electrical gear application.

Hopefully this all makes sense.

Check the pan to see if it is dented.A cracked filter or fluid level will cause the same problem.Does it delay while going into reverse or forward?After the repair was the transmission quick learned?The codes are telling you its not engaging according to the speed sensors.Loss of prime,like a 727 after it sits a week.

No delay when going through any of the gears in forward, but jumps a bit sometimes from 1st to 2nd...nothing when switching from forward to reverse or vice versa. Fluid levels all check out and no dents in the pan. Was not quick learned after repairs. Replaced cam speed sensor and trans output sensor.

Will see if I have time this weekend to tear into her to check for everything recommended. Thanks guys! I'll report back. Any other suggestions welcome in the meantime.

It needs an input speed sensor.