Main Unit Inputs, Outputs, Power Supply and Ground

Main unit inputs:

- Power supply (+15 circuit) (20)
- Power supply (+30 circuit) (1)
- Ground (G34P/G33P)
- Antenna signal HF (265)
- CD changer, line input right channel +/- (355)
- CD changer, line input left channel +/- (355)

Main unit inputs, bus:

- Ignition +B (on/off) from DICE (628)
- CD changer information from CD changer (355)
- Vehicle speed (km/h, mph) from MIU (540)
- Rheostat value (0-100 %) from SID (541)
- Rheostat Night Panel (0-100 %) from SID (541)
- Night Panel (on/off) from SID (541)
- Display lighting (0-100 %) from SID (541)
- Steering wheel controls from SID (541) Key correct from TWICE (632)
- Diagnostics communication,

Main unit outputs:

- Trigger voltage, electric antenna (265)
- Mute control, external amplifier (354)
- Line output external amplifier, right channel +/- (354)
- Line output external amplifier, left channel +/- (354)
- Loudspeaker, right channel +/-, front (266F)
- Loudspeaker, left channel +/-, front (266F)
- Loudspeaker, right channel +/-, rear (266R)
- Loudspeaker, left channel +/-, rear (266R)

Main unit outputs, bus:

- Time RDS (hours, minutes, seconds) used by SID (541)
- Date RDS (0 - 31) used by SID (541)
- Month RDS (Jan - Dec) used by SID (541)
- Sound (acoustic information) used by SID (541)
- Text messages (text information for main unit) used by SID (541)
- CD changer control used by CD changer (355)
- Diagnostics communication,

Main Unit:

The main unit is connected to the wiring harness and the bus via 3 connectors (A, B, C) and an 8-pin DIN connector (for the external amplifier).
The purpose of the main unit is to control the system units and functions as a central unit in the audio system, as follows:

- To activate the audio system units by sending "wake-up" information.
"wake-up" can be information sent via the bus or a logic voltage (trigger voltage) via the wiring harness. When the "wake-up"

signal is received, the unit is switched on and becomes active.

Wake-up with trigger voltage (12 V)
- External amplifier (AS3)
- Antenna, electric

Wake-up with bus information
SID
- CD changer
- Control module, DICE

- Receives audio and antenna signals from the units in the system. The audio signals are passed on to the loudspeakers and the external amplifier (AS3) via the main unit outputs.

Main unit power supply:

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

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

Main unit ground:

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