Error codes p0725 and p0700

[megaskillz]

I have a 98 eclipse nt automatic. While the car is cold I have no problems, but after driving around the city for a while the transmission starts shifting roughly. The check engine like comes on and the tranny goes into 2nd gear. (limp mode) I used a scan tool from autozone to read the error codes and it read codes p0700 which is transmission malfunction and code p0725 which is engine speed input circuit malfunction. The guy at autozone said that more than likely its the vehicle speed sensor thats going bad. I paid $85 for a new speed sensor only to find out that it was for a maual transmission. After research I found that for my transmission there is an input and an output speed sensor. I went to the mitsubishi dealership, told them my problem and the parts I was looking for, and they were clueless. All they had in there system for parts was the speed sensor for manual transmission. Since I have the 420a chrysler motor I decided to go to the chysler/dodge dealer and see about the parts. Sure enough they knew what I was talking about and I purchased both input and output speed sensors. I then installed them both and I am still having the same problem. I really do not know what else to do.

I really appreciate it if anyone can help me. Thanks.

[Silver 95 GST]

First I would change the transmission fluid if it hasn't been changed recently. If this doesn't help, look for into your error codes. Autozone (or some local parts store) should be able to give you a print off of an explanation of the code and possible causes/parts to replace. Hope this helps.

[Colt4G63 also]

You skipped an important step between scanning it, and putting parts on it. "Diagnosis"!
There's a reason AZ scans your car for free: The price is a direct reflection of what the service is worth given the skillset of the boob performing the job. They do it so they can sell you something, (perhaps a sensor that has nothing to do with your problem). They want to sell you the VSS because that's what they have, they don't sell the input speed sensor. You may want to actually look at the waveform coming from the sensor, and check continuity from the sensor to the ECU. At least that's what I would have done. Bear in mind the sensor may work! If the transmission is slipping you could end up with codes like this. The ECU monitors the speed of the input and output shafts, then compares those to the speeds it would expect in any particular gear. If something slips, you get a fault code.

[megaskillz]

Thanks guys I appreciate the info. Three years ago which was about 30k miles ago I had the transmission rebuilt and flesh fluid put in. I had problems since then with the input and output sensors through the years and thats why assume it was again the problem in this case. The guy at autozone did print out a sheet of possible causes, but it read engine speed input malfunction, input speed sensor, and a list that pertain to the same thing. One thing I did notice is that this problem began when the engine ran a little hot because of a faulty radiator fan motor. Pressure was building in the cooling system and coolant was leaking a little near the coolant temp sensor. I dont know where else exactly it was leaking but for sure on that side of the engine. Since then I replaced the radiator fan, drove it for about a week and then the same problem.

I've done some research and found other people have this same problem with other chrysler/dodge vehicles with the same transmission. A guy with a dodge caravan had a similar problem with hard shifting and going into limp mode and a technician from the forum suggested that if could be the crank position sensor. What is your take on this guys?

[megaskillz]

Well its been almost a month and I just figured out the problem. It was a faulty crank position sensor. I bought another CKP for $20 on ebay compared to $111 it would have cost from the dealer. Thanks guys for the help.