Chrysler Repair: 2000 Cirrus: speedo/engine/power windows flaky pt2, powertrain control module, 4 digit numbers

Question
Had to start new question, website told me "too many follow-ups".  Here's where we left off:
Hi Andrew,
The best approach would be to get a fault code readout for any coded numbers stored in the engine and transmission controllers. Sometimes you can do it with the ignition key:"on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the odometer window in the cluster to see if the mileage reading changes to show any 4 digit numbers, preceded by a P. Let me know what they are and we'll go from there. If that doesn't work, then find an Autozone parts store where they often do such a readout using a plug-in code reader for free. Be sure to get the code numbers, ask what they mean, what to do, and how much. Then we'll compare to the shop manual advice. An independent shop will do a readout for under $40 if there is no Autozone nearby.
I suspect that once we get some clues about what is going on this behavior will make sense. I can't visualize exactly what is going on so using the self-diagnostic capability of the car itself if the way to go.
Roland

ON-OFF-ON-OFF-ON didn't work so went and got car scanned.  Recently replaced TCM and had to disconnect battery cable to replace ignition switch so we couldn't get a reading off of that.  ECM error code P0601 Engine Computer Malfunction. ECM? Hope the code helps get the cogs turning.  Thanks again for your continued responses.
Andrew

Answer
The 0601 has only one remedy: replace the ecm. The ecm is also known as the pcm (engine control module=powertrain control module). You may be able to find a used one: make sure it is for the same model year and engine and vehicle model. If you have a sentry key immobilizer (smart key) a dealer will need to reprogram it. Otherwise it should be compatible.