Chrysler Repair: Computer change-out details: 98 Concorde, 1998 chrysler concorde, chrysler concorde

Question
We have had electrical problems with our 1998 Chrysler Concorde for 2 years.

The car was born with a 2.7.  We were told before we bought the car that after 40,000 miles, the engine was replaced with a 3.5 out of a 1999 300M.  We were also told that when the engine was replaced, the car would only run with the original computer from the 2.7 engine, it would not run with the computer out of the 3.5.  

After we bought the car, we had no problems for another 30,000 miles.  Then the electrical problems began.  First, the speedometer, heater, and all gauges would work intermittently.  We drove it like this for about a year.  Then one day, the car quit running.  We were told that the computer was bad, so we sent it to one of those online computer people and they exchanged it for another computer.  We believe that they may have replaced our computer with another computer with a different part number.  The car still does not run.  We have since taken the car to 3 different repair shops.  This last repair shop is convinced that the computer is bad.  We would like to buy another computer, but the parts store says there are 4 different computers for our car and they need the part number off of our computer.  We do not have the original computer anymore.  What do you think about this dilemma?  Can we find the part number for the computer we are supposed to have based on the VIN number for our car?  Thanks for your time!

Answer
Hi Karen,
As regards the computer, usually the programmed 'settings' for properly operating the engine are set to match the specific engine size. As the '99 model car could have 3 different engine choices that would explain 3 of the 4 computers. I am not sure what the fourth one would be for. A Chrysler dealer parts department should be able to sort out which computer was used in a '98 with the 3.2L engine.  It may well be the case that the 3.5L wasn't used in your
'98 model but the 3.2 is virtually identical except for size of the pistons. It wasn't available until '99 in which case the computer for a '98 3.2L would be the better one to get.
The failure of the car to operate with the 3.5L computer after the replacement of the engine could have been due to a failure to reprogram that computer to match the data in the body control module and/or the security key immobolizer feature which share serial numbers/security numbers and therefor have to be re-programmed to allow the engine to run rather than be defeated by the security system not disarming. That will need to be done at a dealership now when/if you change the computer.
Have you tried to get the fault code readouts from the car as it sits now? There should be a code that tells you that the computer has failed before I would conclude that is needed. Turn 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 to see the mileage reading change to show a 4-digit number preceded by a P. Let me know that number(s) and we'll go from there. You may have one of many possible reasons for not running that is unrelated to the computer itself. So let us eliminate all the other possibilities before going that route.
Roland