All values measured to ground unless otherwise noted
Conn./Plug/Pin Pin Information Test Value Comments
A2      
A.1 VSS signal input 0-2 VAC, 0-300 Hz with increasing vehicle speed
Radio on:
Output volume increasing step-by-step
Feed from traction system ECM
A.2 "Diagnostic port" for DTC readout and diagnostic purpose No reliable test. Check continuity of wiring  
A.3 CTEL mute ground signal input Radio on, activate CTEL function:
Radio switches to mute and display shows PHONE
Refer to wiring diagrams 82.70
A.4 Circuit 30 power input 12 VDC at all times Feed from F1f10
A.5 Control voltage output for antenna 12 VDC with radio on  
A.6 Circuit 58d input, "Dimmed Instrument Illumination" voltage Varies from 0.5-12 VDC, depending on setting of dimming value
Parking lights on: Radio buttons illuminated
Radio on: Radio buttons and display illuminated
Feed from IC via Z81/4
A.7 Circuit 15R power input Ignition on 12 VDC Feed from F1f3
A.8 Main ground to W19 Approx. 0 Ohms to ground  
B.1
B.2
Right rear audio signal plus output
Right rear audio signal minus output
Radio on > 0.2 VAC across pin B.1-B.2 Note 1
B.3
B.4
Right front audio signal plus output
Right front audio signal minus output
Radio on > 0.2 VAC across pin B.3-B.4 Note 1
B.5
B.6
Left front audio signal plus output
Left front audio signal minus output
Radio on > 0.2 VAC across pin B.5-B.6 Note 1
B.7
B.8
Left rear audio signal plus output
Left rear audio signal minus output
Radio on > 0.2 VAC across pin B.7-B.8 Note 1
C.4
Wake up output for other ECM's Radio on approx. 10-14 VDC

Refer to D. M. Info./Comm.
Vol. 1, 6.1
C.10 Ground to W19 Approx. 0 Ohms to ground  
D Antenna input connector Radio frequency  
D2B IN
D2B OUT
Optical input port
Optical output port
No reliable test  
Note 1 Substitution test for speaker sytems
Use signal generator
Disconnect appropriate speaker and connect to a low frequency signal generator.
Adjust output to approx. 2.5 Vpp and vary frequency over a range from 10 Hz to 15 kHz. Sound should be audible over most of the range, depending of speaker system under test (bass/tweeter)