I will replace the Becker Grand Prix cassette stereo Model BE0780 on my used '89 300E with an Alpine 9826 CD/MP3/WMA receiver. I noticed there are two connectors, a 5 pin and a 4 pin which is next to the power antenna connection.

Looking at the back of the unit and starting from left to right, can somebody tell me what the pin designations are? Are the R and L to be used for speakers? If I disconnected only the 5 pin connector, I still get sound on the speakers. Do I have to rewire the car as recommended by a few car installers that I have talked to, especially the speaker wires? I will not replace the stock speakers for now. Can I still use the stock fader switch in the center console?

Thanks

I am not familiar with the differences between the various Becker models, but the MB CD manual electrical diagram shows the 86-89 radio wiring to be very straightforward (as my 90 300CE's was but not my 92 300TE). The radio (+) feeds the fader control and the fader feeds the speakers (+). The (-) is wired direct to the speakers. A typical wiring adapter (i.e. from Crutchfield) should work fine and would not require any speaker rewiring unless there are special requirements for the speaker wiring for the Alpine unit.
Hope this helps.

By the way I installed the Alpine 9825 unit in both my cars - works great for me. The 300CE wiring was straight up with the Crutchfield kit (I chose to use the fader in the radio because the console fader is defective). The 300TE has the active bass and required special wiring to the rear amp. (I left the fader in the console because it works).

What I did was to cut out the connectors from the back of the old Becker, and soldered my new receiver wires onto them. One advantage is that you can do all your work on a table instead of contorted in the car. Another is that you can keep the very nice factory connectors intact.

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1986 300E 5-Speed 240k mi.

Using a tester, I was able to locate the ignition, +12V, ground, power antenna and speaker wires coming out of my car. These should be sufficient to connect my Alpine 9826. I might eventually bypass the centre console stock fader as it was already defective to begin with.

I have ADS3001 speakers that I want to hook up in addition to 2 front and 2 rear stock speakers. Where is a good location for them in my '89 300E?

Thanks for your replies.