| Number | X-pin, colour | Description |
|---|---|---|
| X610 | 26-pin, blue | Plug connector 3 Heating and A/C control module |
| X611 | 18-pin, natural | Plug connector 4 Heating and A/C control module |
| X613 | 3-pin, natural | Plug connector 2 Heating and A/C control module |
| X614 | 3-pin, black | Plug connector Heating and A/C control module |
| X18153 | 3-pin, black | Plug connector 5 Heating and A/C control module |
| X18341 | 3-pin, black | Plug connector 0 Heating and A/C control module |
| Pin | Type | Description / Signal type | Connection / Measuring notes |
|---|---|---|---|
| 1 | E | Voltage supply, terminal 15 | Fuse F20 |
| 2 | A | Signal, A/C compressor OFF (M51) A/C compressor signal | DDE control unit DME control unit Digital diesel electronics control unit |
| 3 | A | Signal, A/C compressor ON (M51) | DDE control unit |
| 4 | A | Air conditioning system standby signal | DDE control unit |
| 5 | A | Relay activation, rear window defogger | Rear defogger relay |
| 6 | A | Relay activation, windscreen/spray jet heating | Heated front screen/washer jets relay |
| 7 | E | Pressure signal | High pressure switch |
| 8 | A | Blower control voltage | Output stage |
| 9 | Not used | ||
| 10 | M | Component ground, AUC heating | AUC sensor |
| 11 | M | Ground High pressure switch | High pressure switch |
| 12 | E | Signal, switch off consumer load | General module |
| 13 | Not used | ||
| 14 | A | Auxiliary water pump activation | Auxiliary water pump |
| 15 | A | Relay activation, blower unloader relay | Heating blower relay |
| 16 | Not used | ||
| 17 | A | Relay activation, auxiliary fan stage I | Auxiliary fan stage 1 relay |
| 18 | E | Night light signal | Connector, terminal 58g |
| 19 | E/A | K-bus signal line | K-bus connector |
| 20 | A | Left water valve activation | Water valves, Left valve |
| 21 | A | Right water valve activation | Water valves, Right valve |
| 22 | A | Supply High pressure switch | High pressure switch |
| 23 | A | Sensor positive supply | AUC sensor |
| 24 | E | Negative activation | AUC sensor |
| 25 | A | Positive supply, AUC heating | AUC sensor |
| 26 | Not used | ||
| Pin | Type | Description / Signal type | Connection / Measuring notes |
|---|---|---|---|
| 1 | E | Actuating signal | Fresh air flap motor |
| 2 | A | Actuating signal | Fresh air flap motor |
| 3 | A | Actuating signal | Fresh air flap motor |
| 4 | E | Actuating signal | Fresh air flap motor |
| 5 | E | Setpoint, mixing air actuator | Rear mixing air actuator |
| 6 | A | Sensors (+) | Temperature distribution potentiometer, Rear mixing air actuator |
| 7 | E | Setpoint, mixing air actuator | Temperature distribution potentiometer |
| 8 | E | Sensor signal | Right ventilation sensor |
| 9 | E | Sensor signal | Left ventilation sensor |
| 10 | E | Signal, ventilation ON | Rear passenger compartment ventilation switch |
| 11 | Not used | ||
| 12 | Not used | ||
| 13 | Not used | ||
| 14 | M | Component ground | Sensor and actuator |
| 15 | E | Sensor signal | Evaporator sensor |
| 16 | E | Sensor signal | Right heat exchanger sensor |
| 17 | E | Sensor signal | Left heat exchanger sensor |
| 18 | Not used | ||
| Pin | Type | Description / Signal type | Connection / Measuring notes |
|---|---|---|---|
| 1 | A | Control voltage | Left actuator motors and recirculated air |
| 2 | M | Ground, actuator motors | Left actuator motors and recirculated air |
| 3 | E/A | MI-bus | Left actuator motors and recirculated air |
| Pin | Type | Description / Signal type | Connection / Measuring notes |
|---|---|---|---|
| 1 | A | Control voltage | Right actuator motors and defrosting |
| 2 | M | Ground, actuator motors | Right actuator motors and defrosting |
| 3 | E/A | MI-bus | Right actuator motors and defrosting |
| Pin | Type | Description / Signal type | Connection / Measuring notes |
|---|---|---|---|
| 1 | A | Signal, independent heating ON | up to 1995_08 Independent park/auxiliary heating as of 1995_09 Receiver, independent heating |
| 2 | A | Control voltage | Solenoid valve independent heating/ventilation II |
| 3 | E | Independent heating ON feedback | Independent park/auxiliary heating |
| Pin | Type | Description / Signal type | Connection / Measuring notes |
|---|---|---|---|
| 1 | A | Positive supply, magnetic clutch | High pressure switch (M51) Heating and A/C control module |
| 2 | E | Voltage supply terminal 30 | Fuse F11 |
| 3 | M | Ground | Ground connection X492 |