Two days ago my 2002 chrysler t&c had its check engine light go on. The CEL stayed on for just one start but after it went away and ever since the the gear indicator lights are all lit with boxes around each. The van appears to be in limp mode and does not seem able to get out of 2nd gear (when getting to about 40-45 mph the rpms go up to about 3500-4000 without shifting). The speedometer no longer moves.

The van has various other issues and leaks, but it had previously been riding fine and the transmission seemed fine. Earlier in the same day that all this began my wife scraped the bottom on a inclined entry to a parking lot coming off the main road.

I got the codes p1684 and p0700 from turning the key. Although I did jump another car using the battery on this van, perhaps within the last 50 starts, the battery has not been disconnected.

I brought the van to my mechanic who was only able to get the p0700 code. I do not know for sure and should have asked, but I believe he was using the better scanner to get the more detailed code (I can find out for sure tomorrow about his scanner). He said he would have expected to get additional codes but that he was only able to get p0700. This lead him to think the TCM was bad or that some wires might be cut or shorted. He checked the wires to the tcm and in the front of the car where the scrape occurred but they seemed fine.

I asked him about speed sensors since my research here and elsewhere online led me to believe this was a possibility but he said if that were it he should have gotten additional codes besides the P0700.

Any advice or suggestions? Should I get a second opinion from a trans shop or a dealer shop? Should I look to an aftermarket tcm rebuilder? (such as: http://www.autocomputerexchange.com/) and try swapping out tcm modules?

I'm not looking to spend much because the van has other problems and we were looking to sell and get a full sized van in the next 6-12
months anyway (we have 5 kids now and are quickly outgrowing the t&c). But we weren't looking to buy another just yet and would be happy to find a relatively cheap way to keep this one going for just a bit longer.

Thank you for any suggestions the wisdom of the group might be able to offer.

Eric

 

take it to a tranny shop they will have the scanner that will be able to get into the tranny computer to see the real codes p0700 is a generic code for the tranny has an issue

 

Thanks a lot. You're right. I spoke to the guys who looked at it yesterday and they said they used just a generic code reader. So I dropped by and spoke to a local trans guy today and he's going to get it in tomorrow, read the specific codes and take a closer look. From talking with him he believes it's not the transmission itself but rather is a bad wire or connection somewhere or else the speed sensor. It's looking hopeful at this point!

Thanks again for your reply, I appreciate it.
Eric

 

I was wondering what the final resolution was on the problem. My 2002 has just started the same thing. Thanks in advance.

 

Hi guys having a similar problem getting P700 and P720 fault codes, but the speedo works and in limp mode, any answer

 

The p0720 is for the output speed sensor. First suggestion is to inspect the wiring harness at the sensor for wear/breaks/critter teeth marks. If no issues, I would suggest replacing the speed sensor. If that does not work, I would suspect the alternator is failing and allowing a significant ac (alternating current) ripple that is affecting the speed sensor signal.

It does not seem obvious but the speed sensor on chryslers seem to be be very sensitive to excessive ac ripple.