Those things are so gawdawful ugly.
So you're sure all connections are clean and tight (did you know they have pin testers to see how tight the grip is for these finicky plugs now?), you've swapped the E & F coils to other locations, and still have the codes after replacing the PCM?
Some googling says: http://www.permoveo....er/Default.aspx
Is the engine misfiring presently? If not, the problem is likely intermittent. Try wiggle testing the wiring at the #3 coil and along the wiring harness to the PCM. If manipulating the wiring causes the misfire to surface, repair the wiring problem. Check for poor connection at the coil connector. Verify the harness isn't misrouted or chafing on anything. Repair as necessary If the engine is misfiring presently, stop the engine and disconnect the #3 coil wiring connector. Then start the engine and check for a driver signal to the #3 coil. Using a scope will give you a visual pattern to observe, but since most people don't have access to one there's an easier way. Use a Voltmeter in AC Hertz scale and see if there's a Hz reading of between 5 and 20 or so that indicates the driver is working. If there is a Hertz signal, then replace the #3 ignition coil. It's likely bad. If you don't detect any frequency signal from the PCM on the ignition coil driver circuit indicating the PCM is grounding/ungrounding the circuit (or there is no visible pattern on the scope if you have one) then leave the coil disconnected and check for DC voltage on the driver circuit at the ignition coil connector. If there is any significant voltage on that wire then there is a short to voltage somewhere. Find the short and repair it. If there is no voltage on the driver circuit, then turn the ignition off. Disconnect the PCM connector and check the continuity of the driver between the PCM and the coil. If there is no continuity repair the open or short to ground in the circuit. If continuity is present, then check for resistance between ground and the ignition coil connector. There should be infinite resistance. If there isn't, repair the short to ground in the coil driver circuit NOTE: If the ignition coil driver signal wire is not open or shorted to voltage or ground and there is no trigger signal to the coil then suspect a faulty PCM coil driver. Also keep in mind that if the PCM driver is at fault, there may be a wiring problem that caused the PCM failure. It's a good idea to do the above check after PCM replacement to verify there won't be a repeat failure. If you find that the engine isn't misfiring, the coil is being triggered properly but P0353 is continually being reset, there is the possibility that the PCM coil monitoring system may be faulty.
Which sounds like pretty sound diagnostic advice IMO. Only issue being you may want a wire diagram or PCM I/O pinout. And you definitely want to check this with a High Impedence DIGITAL meter if you decide to try the DVOM method. Computers don't like analog meters for the most part.
Much more helpful than the Schysler forum. http://www.chryslerf...pacifica-14116/
Hopefully his name is not an indicator of occupation, "Chrysler Tech" says code P0355 doesn't exist.
I do still suspect that alternator as they can cause some crazy wacky issues, especially with that kind of mileage it may be beginning to go bad. You might try checking for AC ripple on the output lead.
Problems like this kinda remind me of the RF interference problems Lincoln had on the 04-06 LS. If one of the coil packs near the electronic throttle body went bad It would screw with the data signal sent out by the ECU and would confuse the ECU. It would set a code for the throttle body and go into Limp mode. Very strange occurance. Not sure how often it happens now since they had a campaign to replace the COPs on all of them.
I just read the thread you linked to! Too funny!
Edited by Fairtax4me, 01 November 2012 - 04:55 PM.