This is for a USA F40 but I think the same system is used on the 348 and many other Ferraris of that era. My driver's side mouse belt seems to be acting up. It engages on both the A and B stop, and the seat motor for the diagonal belt that pulls the belt snug works. However, the little red seatbelt light in the lower center of the speedometer does not turn off. I recall at times I had to give the diagonal belt a little tug to get the light off but this is not working. I suspect the problem may be in the rewind/motor device that pulls the diagonal belt snug but am just guessing. I have cleaned the micro switches as best I can. There is quite a bit posted on mouse belts on this site and it is helpful, but nothing I could find about the seat belt light remaining on. I even found a nice diagram on how the system is wired but it is beyond my ability to figure out without some help. Before I go tearing into something I know little about I would appreciate any comments. Thanks folks. Regards, Drew
The 348 version comes in a couple of varieties. I don't know which is closest to the F40. Ferrari produce diagrams for these type seat belt systems, but there are are pieces missing. What year is your F40 and is it closer to the 348TB or 348GTB? Here is one of the diagrams I produced for the 348GTB: https://www.dropbox.com/t/G82M0hYmSawOF6uN Some parts of it are based on photos. I haven't had the chance to do wiring checks on the actual car (There are no mousetrack seatbelts in Australia). At least with a hard fault, you might be able to do wiring checks on the 9-pin motor assembly plug to see which switches don't change state with the belt at various positions. Looking at the diagram, it's hard to do tests on some of the switches because some are in parallel with each other. If the wire colours are different, you may have to do wiring checks further upstream at the ECU. I don't know enough about the seat belt reel assembly to do wiring checks on them. There are 3 wires going to the reel assembly. Note that the backup receptacle can cause the light to come on. If the seat belt is operating normally, but the light is on, I suppose there could be an ECU issue. Have you tried swapping ECUs? How hard are they to access on the F40?
Here's a portion of one of my 348 diagrams. Image Unavailable, Please Login Maybe you could check the wire colours on your car to see if they match up? I have: black, green/black, pink/black, blue/white, orange/black and blue/black, going to the seat motor assembly. Maybe you could show which colour goes where on this graphic: Image Unavailable, Please Login From memory, I think the graphics of the plugs show the wiring from the pin/contact side (?), not the wire side. I don't know any of the wire locations on the ECU side of the plug. The ECU side being the right hand side of the graphic.
