I offered to fix a C4 Picasso. I plugged in my Diagbox and it didn't pick up the VIN and after it was manually inputted it soon became apparent why it didn't pick it up. It was unable ro read any of the modules. I'll be going back to diagnose the OBD2 port using my own C4GP as a known good reference. The fuse on the battery fusebox has been checked and it is fine. Does anybody know why this would happen?
The whole thing stemmed from am ABS/ESP/handbrake problem. It was taken to a garage who couldn't diagnose the problem and tried a known good used ABS pump which didn't fix the problem. The owner's son posted on the C4 Owners forum (link below) for help and being local and having Lexia/Diagbox I reached out to him.