Chrysler Repair: 96 Cirrus LXi either wont start, or just stops running, chrysler cirrus lxi, 1996 chrysler cirrus

Question
Hi Roland,
I have a 1996 Chrysler Cirrus LXi that seems to have a mind of its own. Some days it just wont start. It will crank all day long, but not fire. Other days it is just fine, and other days it will run and stop. There does not seem to be any rhyme or reason to the behavior. While having the oil changed yesterday, the "check engine" light came on, for the first time ever, and they read a code "505". That i see is a engine idle control function. I replaced the PCU a couple years ago, after another bout of no starting, I think I could be having the same issue again. Your thoughts are welcome.  

Answer
Hi Chuck,
I don't know the detailed history of you PCU failure and what codes if any were displayed at that time so I can't recommend replacing the PCU on the current symptom and code situation. I reviewed the P0505 trouble code remediation procedure in my '98 diagnostic procedure manual for the 2.5L V-6 which I assume is your engine. It states that it means that there is either a short to ground or a short to battery voltage on one or more of the idle air control motor driver circuits. That could either be due to a wiring problem in the iac motor, the harness from the PCU to the motor, or the PCU itself. It then goes thru a series of resistance (to detect shorts to ground) and voltage (to detect short to battery), and resistance tests between the circuits, those measurements purpose is to sort out which type of problem and which driver is at fault. The tests also would reveal if the problem was the PCU. If you have a volt-ohmmeter I would be pleased to xerox copy and send you those 16 sides (8 pages) so you could run the tests. I would appreciate reimbursement of four 39 cent stamps to cover the copying and mailing costs. Let me know a postal mail address if you want these.
Another possibility too is that the air passageway that is controlled by the iac motor or the iac pintel is clogged up and not responding to the motor driver control circuits. That might be what is really wrong, rather than it being an electrical problem at all*. Others have reported this kind of issue as explaining a no start, poor idle on and off symptom. So you might want to remove the iac motor and check the pintel and its passage way as well as the air passageway it controls for the presence of gum/dirt that is impairing the idle air supply control system.
Those are my suggestions for your situation. Please let me know how I can be of further help.
Roland
*The codes are couched in terms of electrical reasons sometimes overlooking other causes.