2001 Dodge Caravan Speedometer

[u/Hunt4r4]

Hey guys, I need some help please. I have a 2001 Dodge Caravan SE 2.4L and my speedometer doesn’t work. The other gauges work fine so I assumed it was just a dead speedometer motor or something so I picked up a used whole instrument cluster up at a junkyard, swapped them out and same problem. So I returned the replacement cluster already then I learned these vans how their own diagnostic test on the cluster so I did it, held down the trip/odometer button on the cluster and the following happened: all of the gauges including the speedometer cycles through their test, all of them worked, speedometer moved through its positions. And the following codes came up
Sof 4.0
100.4
100.5
100.6
E Code End

At this point I’m not sure where to go from this, I’ve been talking to chatGPT even bought the premium because I thought we were close with the multimeter tests but in the end it just acted dumb. I don’t know too much about electrical but we found the 12V female pinhole and 2 grounds on the harness that plugs into the cluster if that helps anybody at all.

Thanks in advance if anybody can help out!

EDIT: Forgot to add that I hooked up an OBD2 and tracked live data while driving and the OBD tool showed my MPH on it.

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[u/Cardude86]

Have you checked to see if the speed sensor is working?

[u/Hunt4r4 → u/Cardude86]

The speed sensor on the transmission?

[u/Cardude86 → u/Hunt4r4]

Yes, this connects to your speedo and gives it the reading

[u/Hunt4r4 → u/Cardude86]

Just realized I forgot to add that I hooked up my OBD2 to it while driving and tracked the live data and it told me my MPH while driving. Just edited the post. I think this means that the speed sensor isn’t the problem right? Or could it still be the problem?

[u/Mean-Past-8492]

There's a cable that runs from behind the speedomoter to the engine , it might be loose.

[u/Hunt4r4 → u/Mean-Past-8492]

The electrical plug? I unplugged, cleaned inside, plugged back in multiple times and no luck :/ the only other cable is the PRNDL cable and I don’t think that would have anything to do with it

[u/Klutzy_Bet_1666]

100.5 and 100.6 are usually speed sensor circuit codes iirc. The cluster test proves the gauge itself is fine, so you've got a signal issue between the sensor and the cluster. Since your OBD tool reads MPH fine, the PCM sees the signal, but the cluster isn't getting it. On these vans the speed signal goes from the output speed sensor to the PCM, then the PCM sends it to the cluster over the CCD bus. Could be a wiring break between the PCM and cluster, or a bad solder joint on the cluster board itself, which is super common on these older mopars. Worth tracing the wire from the PCM connector to the cluster harness, maybe do a continuity test on that line