Seat belt idiot light & warning chime weirdness

[Pete_89T2]

I've had my S5 T2 (US model with motor-mouse seatbelts) for about 15 years now and its NEVER done this...

Passive seat belts work perfectly normally as they should, but now the warning chime comes on and beeps at me until I fasten my lap belt -- it's NEVER done that before! Then as I'm driving around, the seatbelt idiot light will randomly come on (with my belt buckled), and it flashes in what seems to be a sequential pattern, almost like it's some sort of error code similar to the ECU/check engine light codes. Fortunately the warning chime DOES NOT come on while the belt idiot light is flashing. Then it will eventually randomly stop doing this! Doesn't seem to matter if I unfasten my lap belt & refasten it, or fasten/unfasten the passenger lap belt.

Did some digging in the FSM, and it doesn't say anything about flashing error codes on the passive belt system. Anyone have a clue as to what might be going on? From the schematics, the seatbelt warning chime & belt idiot light gets wired to the "CPU", which is one of those FC electronic parts known to have cold solder joint failures. That would be my 1st guess. Anyone else have any ideas?

[chibikougan]

I am trying to think but isn't there a small ground with the lap belt? Wiring on the right side ?


Wiggle?

I took mine out for a harness and I thought there was a ground wire there.......

My shoulder strap was seized as per.

[Pete_89T2]

The schematic shows 2 "retractor switches", which *I think* are physically located in the mechanical lap belt retractor mechanism. Looks like their function is to complete a circuit to ground when the lap belts are extended (thus presumably buckled), to cancel out the idiot light and chimes.

Will need to dig into this one while my car is on winter hibernation. Tried wiggling the lap belt and fastening/unfastening it a few times while driving, and it doesn't seem to change anything. The idiot light issue is intermittent.

[chibikougan]

Maximum Overdrive is happening?

[MolotovMan]

My GTUs did that as well, I never looked into it. I would say "retractor switches" are a plausible thing to check for at the lap belts in the console. I can see the switch contacts getting hairy after 25 years!