Perfekt erklärt, lovegood

"E2"or "E3" (Without CD Changer)
1 Input Power to the RECEIVER UNIT (Trunk mounted) is missing, Check with volt meter to test
for 12 volts
2 Fuse of the RECEIVER UNIT (Trunk mounted) is open, Replace it with 7.5 amp fuse.
3 The BUS CABLE (gray colored) that connects to HEAD UNIT(dash mounted) to the
RECEIVER UNIT(trunk mounted) is not connected or is defective.
4 RECEIVER UNIT(trunk mounted) is defective.

Ich hatte auch eben nochmal nachgeschaut...