Instruments go haywire during acceleration
 

Recently, I have been experiencing significant issues with the instruments on my 2005 Chrysler Pacifica. After 20-30 minutes of driving, I start intermittently losing all instruments and the check engine light comes on. This seems to only happen while I am accelerating... but the check engine light stays on afterwards. About half of the time, the "Passenger Airbag off" light illuminates and the display to the left side of the dash indicates "Service immobilizer"

Autozone was not able to connect their code reader... but they tested the alternator and the results indicated it was going out.

I replaced the alternator, but the issue remained.

Noting that some of my other recent issues (Cruise Control, Horn, Headlights) and the Integrated Power Module all utilize Ground 103, I replaced the connection between these ground wires and the frame.

The issue remained. - AND my wife ran into a new issue where the car would die when shifted out of park.... but only when it had been running for a while and there was a significant electrical load (AC, Radio, etc.)

I replaced the Integrated Power Module with one I had on hand from when I was working with the previous headlight issue.

The issue remained.

I plan to test the continuity of the remaining Power Module ground wires... but thought I would check here to see if anyone here had any other advice. I don't plan on keeping this car for much longer, but really need it to last through the end of the summer.

Well this sounds like a strange issue especially if it only happens after driving the vehicle for a while. More information would be very helpful. First, what codes are showing. This is the first thing we need to know. If you've had problems with the cruise, horn and headlights, what did you have done to fix these issues? Does the vehicle stall only when it's hot with a high elect load? Will it run OK without an elect load when it's hot?? I hate to guess with any problems but I would check all fuseable links, wiring connectors to the PCM which is behind the driver side wheel well (really dumb place for it in my opinion), and all elect connectors and grounds. At first thought it sounds like wiring somewhere has a bad connection and when it gets hot it's causing a short or losing a connection somewhere, but this is just a guess. Something to think about. Engine codes are what we need to know to start with. I've seen many stalling problems caused by a bad MAP sensor but this doesn't sound like a MAP sensor problem. Do you only have these problems when you put a high load on the electrical system? Does this happen with a high E load when it's cold? How old is the battery? Was it checked when hot? We need more details and any engine codes.

I haven't been able to consistently connect the code reader to the car, but when the connection was last successful, these are the error codes I noted:
U110C - Lost Fuel Level Message
P1684 - Battery power to module disconnected
9 - Current Vehicle Identification Number Missing/Mismatch
8 - Vehicle Body Style Unknown / Mismatch
4 - J1850 Bus Shorted to Battery <---- Just had an epiphany.... this may be the issue right here
2 - Occupant classification undetermined
80 - Occupant Classification Module (OCM) Active Diagnostic Code
31 - Vehicle Body Style Unknown/Mismatch

When the headlights went out several years ago, my dealer reccomended replacing the Integrated Power Module. After that didn't fix the issue, I discovered that the headlights had an open ground. I replaced the existing ground wire with a new one that I ran directly to the frame.

The Cruise Control continues to be an issue. I replaced the servo and all vacuum lines a few years ago, but it still wouldn't engage. I've just been living without the cruise control in the meantime.

One of the two horns stopped working a few weeks ago. Replacing the connector at ground G103 last weekend resolved the issue.

The issue with the instruments and stalling is relatively new, so I can't definitively say whether it is a hot or cold weather issue. The weather has been consistently warm since it first started occurring.

While it seems that both the instrument and stalling issues are only occurring when there is a high load (AC + Radio for example) I haven't spent much time without the AC on recently to confirm that the issue doesn't occur with lower electrical loads. (I will try that today)

The stalling issue has only occurred once... and turning off all electrics and letting the car cool off for 20 minutes seemed to get us past the issue for now.

WOW! This is certainly the strangest situation I've ever heard of concerning codes. Why can't you get a code reader connected? Are there any broken wires or problems there? How long have you had this car and where did it come from? Is it a salvage title? I'm wondering if this thing was ever flooded or pieced together with parts from another vehicle. I don't understand why you'd be getting vehicle VIN and body style mismatch codes??? Has the computer ever been replaced that you know of? Can't say I've ever heard of codes like this coming up all at once. I was wondering if maybe the battery had an intermittent short that happens when it gets hot. I doubt that would cause all this but definitely check all the wiring and connectors. Being an 05 its getting up there in years. Don't know where you live but up here in NY there aren't many if any 05's left that are still running (legally anyway). Mine is an 06 that I bought last year in Virginia. It didn't even have any rust underneath and was so clean I didn't care if I had to put a new motor or trans in it. It was kept in a garage too so a really lucky find. I took apart an 08 last year and the PCM had so much corrosion on it that the mounting bolts broke before they would turn. It's mounted on the front side of the driver side wheel well, just behind the well. If the well has any cracks or holes in it , take a look and make sure all the connections are ok. Honestly I really don't have any more ideas. If you have another battery you can swap with it might be worth a try. When anything shorts out or any amount of voltage gets back to the computer all kinds of havoc can result. For example a diode in the alternator goes bad and allows dc to get back to the computer and it throws trans codes and makes the speedo jump around when stopped in drive etc. I hope you can figure it out. I'd love to know what it is if you find it..