Technical Fiat 500 1.2 with 3 error codes

[AntonyB]

Hi everyone,


I've recently purchased a 2007 Fiat 500 1.2 automatic, and I'm dealing with several warning lights and fault codes. The car has been scanned, and the following fault codes came up:

• U0422-00 Fire Prevention System (FPS) – Alive/sequence counter incorrect
• U1726-86 Sensing and Diagnostics Module – Signal invalid
• U1733-86 CTM (Convergence Telematic Module) – Node faulty on B-CAN, signal invalid
• B1033-12 Daytime Running Light – Circuit short to battery
• B1022-12 Front Parking Light – Circuit short to battery

The wiring for the lights is visibly damaged. I've already ordered replacement wiring and plan to fix this over the weekend. However, I’m still left with the other three fault codes.


The car drives and shifts fine, but the following issues remain:

• Airbag warning light is on
• Seatbelt warning light is on
• Start-stop system is not functioning
• Steering wheel buttons all work except the one with the Microsoft logo (Blue&Me) – that does nothing
• The car’s USB port is also not working
• Odometer blinking

Based on what I’ve found online, it seems I might need to replace the airbag module and the Blue&Me module. However, I’m concerned that the root cause could actually be the Body Control Module (BCM), especially since U0422 relates to that.


I’m afraid I’ll replace the airbag and Blue&Me modules, only to find out the issue was actually with the BCM all along.


Is there a way to test these modules to confirm which one is faulty before replacing them? I have carly OBD scanner, multimeter and a lot of other tools.
I’m fairly confident with mechanical work, but my electrical skills are limited.


Any advice or guidance would be greatly appreciated!


Thanks in advance.