service information

TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERS

DATE: February 1992 REF. NO. MBNA 82/58

SUBJECT: BECKER TWO - PIECE RADIO ERROR CODES

The Backer two - piece radio has a self-diagnostic system. The system verifies data exchange via the BUS cable between the dash mounted Radio control unit (A2/4), CD changer (A2/6) and trunk mounted Tuner/amplifier (A2/31. If a fault is detected, an error code, E1 through E5, will appear in the radio display. There is no procedure required to access radio error codes.

The Diagnostic chart below cross references error code - possible cause - remedy.

If more than one remedy is listed, they are to be performed in the sequence listed.

Chart

Possible Cause Remedy

Code

E7 EE PROM in radio control unit defective Replace Radio control unit (A2/4)

E2 ` Radio control unit, CD changer and Check BUS cable connections on Radio

tuner/amplifier will not turn ON due to control unit (A2/4) and CD changer (A2/6).

open circuit. or poor/no connection of BUS Check for continuity between pins on BUS

cable; or no voltage cables.

;Check condition of fuse on rear of CD

'

Changer and tuner/amplifier (A2/3). Check for circuits 15, 30 and 31, at the radio control unit, CD changer and tuner/amplifier.

Replace Tuner/amplifier (A2/3).

E3 Tuner/amplifier will not turn ON due to Check BUS cable connections on CD

open circuit or poor/no BUS connection changer (A2/6) and tuner/amplifier (A2/3).

between CD changer and tuner/amplifier; Check for continuity between pins of BUS

or no voltage to tuner/amplifier cable from CD changer to tuner/amplifier. Check condition of fuse on rear of tuner/amplifier. Check for circuits 30 and 31 at tuner/amplifier: Replace Tuner/amplifier (A2/3).

E4. Tuner/amplifier and/or CD changer will not Replace Tuner/amplifier (A2/3) and/or CD

turn ON. BUS communication OK changer (A2/6).

E5 Tuner/amplifier will not turn ON. BUS Replace Tuner/amplifier (A2i3).

communication OK