Main Unit, Inputs Bus, Outputs Bus, Power Supply, Ground

Main Unit Inputs

Main Unit Inputs:

- Power supply +15 (20)
- Power supply +30 (1)
- Ground (G34P/G33P)
- Telephone mute (375)
- Telephone line input +/- (375)

Main Unit Inputs, Bus

Main Unit Inputs, Bus:

- Ignition +B (on/off) from DICE (628)
- Steering wheel controls from SID (541)
- Key Correct from TWICE (632)
- Diagnostics communication, see Bus and diagnostics communication.
See Powertrain Management/Computers and Control Systems/Information Bus

Main Unit Outputs

Main Unit Outputs:

- Mute control, external amplifier (354)
- Line output, external amplifier, right/left channel +/- (354)
- Loudspeaker, right/left channel +/- front/rear (266)

Main Unit Outputs, Bus

Main Unit Outputs, Bus:

- Sound (acoustic information) used by SID (541)
- Text message (text information for main unit) used by SID (541)
- Diagnostics communication, see Bus and diagnostics communication
See Powertrain Management/Computers and Control Systems/Information Bus


Main Unit

Main Unit:

The main unit for the telephone system is the audio system main unit. It is connected to the wiring harness and bus via 3 connectors (A, B, C) and an 8-pin DIN connector (for external amplifier).

The task of the main unit in the telephone system is as follows:
- Disconnect normal sound from selected source during a call. This is achieved by sending a mute signal to the main unit, which then disconnects the normal sound from the loudspeakers and the signal to the external amplifier if fitted.
- To receive an audio signal (line input) from the telephone (incoming sound) via the telephone connector and reproduce it via the audio system speakers.
See Test readings, control module connections

Main Unit Power Supply

Main unit power supply:

Power supply +15
From fuse 24 to the main unit, pin 4(A).

Power supply +30
From fuse 13 to the main unit, pin 7(A).

Main Unit Ground

Main unit ground:

Ground connection
The main unit is grounded (main ground) to grounding point G34P via pin 8(A).