Chrysler Repair: 96 Stratus guage cluster not working, water intrusion, water leaks

Question
My daughter has a 96 stratus that all of a sudden stopped working but would come on off and on.  Now it has not worked for some time but the temp and gas gauge work some times but the speed and tach and digital trip window will not work.  For the most part the whole cluster is off more than on and when it is off the car does not run or shift right.. I tried a new cluster but that did not work either.  Any pointers as to where to start?  

Thank you so much.

Answer
Hi Rusty,
All the data that cause the cluster to read come in on a single pair of twisted wires as a digital signal from the body computer. Also the data for the speed/odo and the tach come to the body computer from their control modules for the engine and the trans. Interestingly all the wires I speak of are in a single 14-wire black plug at the body computer and are in fact grouped togeter at one end of that plug. That raises the possibility for example that there is some water intrusion from the windshield which may have leaked down onto that plug and shorted together some of the wires. Have you noticed any such water leaks on the driver's side under the dash?
You could verify this possibility by getting a fault code readout for free at an Autozone parts store and if they find a code related to communication problems that would corroborate that possibility. You might also try an ignition key readout approach which is less detailed: "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the check engine light to begin to flash, pause, flash, etc. Count the number of flashes before each pause. Then repeat to verify accuracy of the counts. Combine the counts in pairs in order of appearance to form the 2-digit fault codes. then let me know those codes and any 4-digit codes that you get from an Autozone readout via the datal link connector under the dash by the steering column and we can go from there.
The removal of the bcm to check the plug involves some of the same step you took to replace the cluster and I can tell you the others.
Roland