My in-laws gave me this van and I knew it had problems but I really need it to get back and forth to work. They had the transmission rebuilt a couple of years ago and even after that when it would get to hot (I live in Arizona so it's friggin HOT now) the van would stop shifting. The solution has always been to pull over, turn off the van and let it sit for about 10 seconds. Once it was turned back on the van would begin shifting again and we could be on our way.

Last week it stopped shifting completely and after doing some looking online I decided to replace both the input and output transmission speed sensors. The van ran great for about 40 miles. It shifted like nobody's business and then.... When I was 40 miles from home it stopped shifting again. I limped it back toward home and stopped at an Auto Zone on the way, had then hook up their little diagnostic thing and it came back with several error codes, one of which said the output transmission speed sensor was either bad or there was an electrical issue. We yanked that sensor back out, took it back and got another one and then put it in. The van still isn't shifting so I started digging some more. There were three other codes that pointed to the transmission control module so I have ordered one online.

These are the error codes I got:
P1698 - no CCD message from TCM. Possible causes: open CCD bus line or failed TCM

P0731 - Gear ratio error in first gear (the van currently will not shift out of first gear) The ECM has detected that the transmission output RPM does not match the transmission input RPM. Possible causes: check other service codes first (WOW, that told me a lot! lol), TSS error, poor electrical connection, internal transmission fault.

I had one more but it's down in the van. It was the one that said the transmission output speed sensor was bad though.

So...... I have a used TCM ordered but if that doesn't work then I am still going to be scratching my head. Any thoughts or suggestions? Should I just take the van and drive it off a cliff maybe?

 

I wanted to add to my original post... The thing that initially led me to replace the input and output transmission speed sensors wasn't just that the van wasn't shifting gears, the speedometer was also going crazy..... It was really laggy, bouncing around and sluggish to go up but then it would jump all the way over to 120 and then come back down again.

 

Well..... we replaced the transmission control module today but now there seems to be even more going on. There's now also no power steering, despite the reservoir having fluid in it. The transmission goes in to reverse with no problem at all but still doesn't shift out of first gear and the speedometer is still bouncing around all over the place.

I had one other thing that popped up in a few of the codes that I was able to grab a week ago. Oh yeah, no service engine light now either so we can't check to see if there are any new codes....Now I am looking at the electronic control module. Before they gave us the van and for the past five years or so of driving it, they haev been saying they'd been told the "brain of the van" needed to be replaced and that is the ECM.

I watched a video online about how to reset the ECM, much like resetting the BIOS of a motherboard in a desktop computer. I work on computers so this actually made some sense! The video said to find the ECM/ECU fuse in the fuse box, pull it for at least 30 minutes, put put back in and then let the vehicle idle for 5 minutes before trying to drive it. We didn't find a fuse labeled ECM/ECU, we found one labeled "memory" and when we pulled it, nothing in the van worked; no lights, door locks, nothing so I am thinking it must be the correct fuse.

For the love of God, does anyone have any advice for me here??? I am very close to just junking this thing and trying to buy another car but I love this van and ideally I'd like to be able to keep it and actually DRIVE it. I just paid for another month of insurance and can't even drive it!

HELP!!!!!!!!!!

 

Nothing concrete but I can throw a few things at you.

The "Memory" fuse, better known as the IOD fuse, is one power source for the Body Control Module better known as the BCM. The BCM controls all the electrical accessories on the van - as you found out. Unfortunately it does nothing for the transmission.

When doing a "reset" of any kind disconnecting the negative battery cable will do the job. Your ECM/ECU fuse may be the "engine" fuse or maybe the EATX relay. EATX just means electronic automatic transmission. When that relay is powered off the tranny is in limp mode.

When any problem pops up involving the CCD data buss it's always worth mentioning a chronic problem effecting 3rd generation vans most commonly called the cracked cluster solder joint issue. Specifically the solder joints securing the connector to the instrument cluster circuit board crack and open the the CCD buss line. Just have to remove the cluster, it's circuit board, and retouch the solder joints with a soldering iron. That has fixed many a data buss problem.

You could try a cluster self test. Push and hold both ***** on the cluster then turn the ignition on. Within a few seconds the lighted indications will start changing the the dials will move to 4 predetermined positions. Once you see something change you can release the *****.

Gear ratio error codes are often caused by the two sensors or their circuits. Worn clutch packs can also do it it. To see if that's the case a shop can read what's called the Clutch Volume Index (CVI) numbers.

 

I would need to know a few answers, Do you know what your CVI's are and have you have a clutch test do? The speedo could because of a bad wire going to the speed sensor or a bad circuit board.

 

I just registered and I have a similar problem. Error message P0731 incorrect gear ratio in 1st gear. My speedometer is not jumping around but the engine will rev to about 2500 rpm before changing gears (happens once in a while). I was told that this problem occurs often in Dodge Grand Caravans. I was told to check the input and output speed sensors and to replace them first because it was the cheapest fix. I just ordered the part today and will try to replace them over the weekend. I ordered the parts via ebay for 17.00 dollars. Will let you guys/gals know how it turns out. Oh Specs on Dodge Grand Caravan 2003 Ex series 3.8L. DJ Digital you may want to check out this link : http://answers.yahoo.com/question/in...3162302AAGflLH

 

My parts for the 2003 Grand Caravan Ex (Input and Output) speed sensor arrived yesterday and I installed them. I did notice that the check engine light was gone and the caravan seemed to run smoothly through the gears. Glad it only costs 17.00 dollars instead of some transmission repair.

 

The problem may have been the input sensor, but replacing both sensors is good.

 

Well, mine is headed for the junk yard lol. I'm just done with this darn thing. I just found out today that I am probably going to have to move at the start of December so I have nothing else that I can do with it at this point. Thanks for all of the info though and keep all those answers coming!