It all depends which pins are connected on the chime/gong. I recently had my one out to test it and I found the following info on the net. My gong has no PDC, so no wire connected.
The gong module attached to the driver's kick panel makes the sounds for the car’s optional equipment, including park distance control and the various Multi-Information Displays (outside temperature display, check control and the OBC). The module also makes the American, key-in-ignition warning and the Japanese, in-reverse warning. It does not make the turn signal clicks or the lights-on warning. An annunciator inside the instrument cluster make those since some cars produce none of the other warnings and, hence, have no gong.

The gong module has two power inputs, and five 12V inputs requesting five different sound programs. The inputs can trigger different sounds by changing from ground to 12V, remaining at 12V, changing from 12V to ground, or remaining at ground.
..... Ground (Klemme/Terminal 31)
+ Constant 12V battery power (Klemme/Terminal 30 via F31)
T1..... low MEMO Signal – the falling edge triggers three, short beeps at a rate of 1.6 Hz. More follow if T1 is held low (remains grounded).
T2......low LIMIT and TEMP Warnings – the falling edge triggers the first chime. More follow repeating at 0.6 Hz if T2 is held low.
T3......low American Key-in-Ignition Warning – the falling edge starts the chime. The tone continues if T3 is held low. The tone fades away over 1.6 s when T3 is taken high. T3 ignores pulses shorter than roughly 20 ms (40 ms always works).
T4.....low Park Distance Control – grounding T4 makes an immediate, quieter, continuous, high pitched tone.
T5.....high Japanese Reverse Warning – a lower pitched, sublime ping similar to T2. Holding T5 high (at 12V) makes repeated pings after a brief delay.

An "active low" input makes noise if you ground it; an "active high" input, if you apply 12V.


As some warnings are more important than others, the inputs sound with the following priority, from highest to lowest.
T3 • Obnoxiously and immediately interrupts all the others.
T1, T2, T4: The three inputs have equal, interlocked priority: an input must go off before the next one sounds.• T1 and T2 interrupt T5 after its current ping.• T4 immediately interrupts T5.
T5 • Interrupted by all the others (as just described).