Diagnosis By Symptom

Fault symptoms
Seat-belt warning not working.

Conditions
Break in the circuit from the relay to the seat-belt warning or break in the circuit to control module pin 9.

Diagnostic help
The control module output can be activated and the input from the switch read with the diagnostic tool.
If the indicator lamp goes on when the control module output is activated, the fault is probably located between fuse 17 and pin 28 on TWICE.
If the indicator lamp does not go on when the control module output is activated, the fault is probably located in the relay (511) circuit to the seat-belt warning (64RL/RR).

Check the wiring
Jiggle the wiring harness at several points and in different directions to reveal intermittent breaks and short-circuits in the leads. Observe the multimeter, test lamp or diagnostic instrument during the test.