[guest676]

I have a 1992 dodge dynasty, 3.3liter, and I know this is a very common problem. It started going into limp mode a couple months ago and would do it occasionally. It got more and more frequent, now every time I drive it, it starts out by attempting to shift, but ends up in limp mode (2nd gear). When it first happened, I changed the transmission filter and oil and that seemed to help but only temporarily. I've changed the input and output sensors on the trans. One other detail, and I'm not sure exactly how this relates, is that the speedometer is often erratic and often reads 80-90mpg when I'm barely moving. Any suggestions would be appreciated, thanks.

 

[valiant67]

You could gamble on the speed sensor again, but the only way to know for sure is to have it scanned with a scanner that can access the transmission codes (most scanners cannot do this).

 

[ImperialCrown]

Welcome to Allpar. Get the TCM fault code, otherwise you are guessing. Some early ones had a 3rd speed sensor at the right side drive axle housing for speedometer. Otherwise it was the output speed sensor under the battery.
Metallic 'mud' on the sensor tip can give erratic speed readings as can wiring harness problems.

 

[85lebaront2]

I second what ImperialCrown says, but will add one from personal experience with two of the older vans, one 3.0L the other 3.3L, both were prone to hitting limp mode while driving, usually at highway speeds. It turned out to be the plugs on the speed sensors were not making good contact and when the signal would cut out so would the transaxle controller. The solenoid pack on the front of the case can cause weird results as it has pressure sensors to tell the EATX controller what gear it is in. The erratic speedometer though may be indicative of a bad EATX controller. As for a scanner, the old Snap-on MT2500 (red brick) could do them and set the pinion factor (speedometer correction) also, the Solus and Modis will also do the transaxle part. Other than finding a shop with those and most transmission shops should have something as everything in recent years is computer controlled you are at the mercy of a dealership and hope there is at least one or more techs older than the car.