Most of the "MY IPC WENT CRAZY AND IS POSSESSED" problems are caused by a corrupted serial data buss. Remember! All the C5 control modules are connected together at the STAR CONNECTORS.
If the serial output of one module gets corrupted, it effects ALL the modules.

The female pins in the SIX Wire Power Connector on the door wire harness, body side (which resides in the hole on the door frame (A pillar) where the accordion tube connects) gets spread apart or deforms.

The male pin then makes poor connection with the bent/spread/damaged female pin. The slightest bump, door slam, or even opening the door causes the male pin to loose and remake connections several times and the serial data output from the Door Control Module/s gets all jumbled up and transmitted out of sequence. So, the BCM and the IPC freaks out.

The proper way to check to see if the female pin has proper grip on the male pin, is to do a pin pull test. Slide a spare male pin in the female pin. There should be a firm pressure or grip as the pin goes IN and the same pressure when you pull it OUT.
If there isn’t any pressure or grip, the female pin needs to be repaired (bend the small tong that makes the proper grip back in place) or replaced with a new pin.

The same thing can happen to the Driver’s Seat connector. It too has a control module and is connected to the serial data buss. The connector can get damaged and or WET (if you have a leak on the driver’s side. That causes the same effect on the serial data buss

Another event that can cause the same symptoms is a WET or DAMP BCM... It DOES NOT like water!!

So,, there you have it..

Bill