93 GV stumble with speedo drop

I have a new to me '93 Grand Voyager 3.3 with 230k miles. I has started stumbling (no specific speed) at the same time the speedo drops. Nothing else seems to be acting up at the time, all of the lights, stereo etc stay steady.

The trans sometimes gets stuck in limp mode, but does not seem to happen at a related time.
Any help would be greatly appreciated!

Classic output speed sensor failure. Check the sensor connection for security/corrosion and wire harness for chaffed wires shorting to ground first. Replacement will cost around $30 at most parts stores. May or may not see the service engine light on. May or may not see a code 15 on the key dance to check for codes. Will fix your first two problems. A maybe on the last.

I had the identical problem on my 93 caravan with the 3.3. I replaced the input and output speed sensors with no relief. I checked the codes, it said my O2 sensor was out. I pulled it and it had one of the four wires broken so I replaced it with a bosch O2 sensor from Autozone for 48 bucks and the hesitant stutters with the speedo bounce and occaisional limp modes and dying altogether while driving stopped presto chango

Replaced output sensor today, no luck. Connector and wires look ok, but I'll give them a closer look this weekend.

I've done a little more looking around. I'll stand by my first diagnosis. The only thing to add is many times when dealerships see this identicle problem they will automatically change both the input and output sensors. To me that's a shotgun approach but, seems to work for them (and their bottom line). I hesitate to say it but, if you don't see anything amiss with the new output sensor installation, you might consider changing the input sensor as well. Looking at the front of the tranny (4speed 41TE) the output sensor is on the right and the input on the left. Beyond that, the TCM is next in line. Don't go there yet.

Not sure this works on a 93 but, you might try an instrument self test. How? Push and hold the trip and reset buttons on the instrument cluster a few seconds. The indicators should cycle a few times. It will only prove the speedo itself is ok. Recommend you check for codes before you do anything.

Replaced the input sensor today, still no luck. Forgot to mention that I checked for codes at each step, did have a 53 Internal Logic Module Problems before I replaced either of the sensors. Nothing after replacing either of them.

That would have been a key thing to pass on. A code 53 is an internal failure of the Powertrain Control Module or PCM. The only fix is to replace it. Now exactly why it disappeared is a mystery. Disconnecting the battery when you changed the sensors could be one answer. That will clear the codes. Did you?

You've gone past my experience level so I am not going to lead you down the path of emptying your wallet with no results. We need more experienced heads looking at this. I recommend you send RickMN a private message and ask him for advise. Another would be 1thunder. How do you do that? Scroll down the threads on the main page till you find the name on the right side. Click it to open their public profile. On the right side of the profile page click send private message. You'll get it from there. Don't dessert your thread. We can fix this.

My book for the 93GV ECM shows that a code 53 is "Internal Controller Failure - Internal engine controller fault condition detected". It is possible your ECM (located behind the battery) is the culprit.

However, I'd check the wiring to the speep sensors as RIP has it correct, the symptoms are dead on for a speed sensor issue. If you've changed the output & the input and you still have issues, check all your connections perhaps something there is causing a fault.

Also, check your main ground connection, and verify your charging system is functioning correctly. Low or wild fluctuating voltages can cause crazy behavior on those systems.

You could also try changing the cam and crank sensors, but that's an act of desperation. If all the connection pass, you can try removing/reseating the ECM connector using DiElectric gel, but BE WARNED, in a vehicle that old that connector may pull some pins out of the ECM meaning you'll need a new one anyway.

If you do go with changing the ECM, tell the dealer you want a refurb, it'll save you big $$$'s, and if you don't specify refurbished you'll never get that price or option usually. There are also some good ECM refurb sources on the web.

Hope this helps!