OEM 2-to-4 channel standard sound adapter harness

No longer available from BMW.

Plugs into fader connector of a 2 channel standard / radio-only audio system. With this adapter you can run an OEM 4 channel radio like the CM5908 or KE83-ZBM without a trunk amplifier in a car with 2 channel wiring.

Picture is the round pin fader connector version.  Flat blade connector version for pre-87 cars also available