Hello Guys,
I am a new user of the forums, but found it from searching for an answer to a question on the internet. Now to my issue…
I have a 02 Grand Caravan Sport, w/ 80k on the clock. The van has never given us any problems until the other night. We were driving home from a store and earlier everything sounded, felt and drove fine. When we start home the check engine light comes on, and then the trans goes into limp mode, I only had second gear. The engine light goes out later, but I am still stuck in limp mode.
I pull the codes and find P0605, Internal Control Module Failure. I assume this is the TCM. The Trans Temp Signal showed the temp at –3 Deg. F, which is obviously unrealistic. My questions…

Sorry, I keep getting the error message when trying to post and have to break this into two...
Is there any way to verify the TCM is my culprit?

Take the van to a Trans shop and have them run the codes on the TCM. It is more than likely one of the speed sensors. This is a very common problem on the A604 trans. It is inexpensive to fix ($35-$40) and typically can be done by a DIY'er. I keep two extra with me now.

PROBABLY THE INPUT SPEED SENSOR

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Darryl Waddy

If it was the speed sensor though wouldnt my speedometer not work?? That is working fine.

Yes, perhaps, but my problem was the output sensor. It caused my speedometer to fluctuate, but worked some of the time. I don't know what happens when the input speed sensor goes bad. I guess it is the first thing to consider, that is if your van was running fine and then all of a sudden... Take it to a tranny shop and let them check the code.

There is a complete service manual on this forum. It is not the Caravan, however, it is for the Dodge Intrepid (2nd Generation). The manual has the sensors in it and how it works with the tranny. If you want you can download it from this forum:

Click on Dodge forum on top menu
In the new window, scroll down to Dodge Intrepid
In the new window, scroll down to 2nd Gen Intrepid
In the new window, scroll down to THE HOLY GRAIL in the topics area
In the new window, click on the link '2nd Gen LH service manual

From there you can download parts I and II of the manual. You will need Adobe reader. When you have downloaded the manual, look in the index and find input speed sensor, then go to it. From there you can educate yourself on either the input or output speed sensors. Or, you can view the other topics that relates to your topic...

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Darryl Waddy

Replace the TCM because there is an internal problem. You will need a DRB3 to set the pinion factor and program the vin too.

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Master Chassis tech, Transmission
Automatic and Manual and Suspensions.
Also repair front and rear diffs and all engine
repairs inc Diesel. A/C repair too.

I researched this forum and read that a person having the same code changed his TCM.

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Darryl Waddy

Thanks for the input guys, I will let you know the outcome.