This guide covers the replacement and wiring procedure illustrated in the source tutorial for the Mercedes-Benz A-Class 177. The source describes fitting the rotating tweeters with adapter harnesses and connecting their lighting to factory or retrofitted ambient lighting.
Vehicle-year check: The source body states 2019-2024, while the product image states 2019-2025. Confirm the vehicle year, ambient-light equipment and supplied kit version before using this guide; the source materials do not resolve that difference.
1. Product components
The numbered component key in the source image is:
- Rotating tweeters.
- Rotation drive modules.
- Adapter harnesses.
- Ambient-light modules.
- Speaker adapter harnesses.
2. Wiring diagram
4D rotating tweeter LIN-module wiring diagram — source Chinese PDF
The following English key translates the numbered callouts in the source diagram. The numbers identify diagram items, not terminal positions.
| Diagram item | Source description and connection |
|---|---|
| 1 | Rotating tweeter, installed in the triangular trim area of the door. |
| 2 | 4-pin lighting connector, unused/reserved in the illustrated arrangement. |
| 3 | 4-pin lighting connector, connected to the lighting module. |
| 4 | Ambient-light module, providing lighting drive and synchronization control. |
| 5 | 5-pin, 3-wire lead. The diagram callout labels it the lighting-module power lead; the lower key states that it obtains the factory ambient-light communication signal. |
| 6 | Main-harness power connector, adapted to the door-control connection. |
| 7 | Drive-module connector, connected to the motor module. |
| 8 | Rotation drive module (motor module), controlling the tweeter motor. |
| 9 | 5-pin, 5-wire motor connection between the drive module and motor for mechanical movement control. |
| 10 | 2-pin, 2-wire speaker connection, carrying the audio signal to the rotating tweeter. |
| 11 | Speaker connector, unused/reserved in the illustrated arrangement. |
| 12 | Speaker connector, connected to the factory speaker wiring. |
The source diagram notes: fully seat every mating connector; professional installation is recommended; test all functions after installation. It also states that the left and right sides use the same connection method.
3. Installation procedure
3.1 Remove the front door trim
Read the source photographs from top to bottom:
- Remove the two front door-trim fixing screws using a T30 driver. The next photograph shows their locations.
- Use a plastic trim tool at the lower edge of the door trim to release its retaining clips.
- Locate the positioning clip at the outer edge of the front door trim, as shown.
- Pull the top of the door trim outward horizontally as illustrated.
- Slide the trim horizontally in the direction of the arrow to disengage the positioning clip. The next photograph shows that clip.
- Release the interior door-handle cable from its retaining mechanism, then disengage its end from the locating clip as illustrated.
- Unplug the front-door connections identified as No. 5 and No. 6 at the door-control module in the source photograph. These are connector identifiers, not pin numbers.
3.2 Replace the triangular trim with the rotating tweeter
Read the source photographs from top to bottom:
- Release the retaining clips and remove the original triangular door-frame trim cover.
- Remove the original retaining clip and transfer it to the rotating tweeter assembly.
- Secure the original clip in the rotating tweeter assembly, as shown. This caption describes the rotating tweeter assembly; it does not instruct you to rotate the tweeter to secure the clip.
- Align the retaining clip with the original mounting hole and fit the tweeter assembly.
- The last photograph shows the fitted rotating tweeter.
3.3 Connect the speaker adapter harness
Read the source photographs from top to bottom:
- Identify the speaker connector on the rotating tweeter and the separate speaker adapter harness.
- Unplug the factory midrange-speaker connector.
- The source shows trimming the indicated plastic locating tab on the factory speaker connector.
- Mate the factory speaker connector with the adapter connector.
- The source also shows trimming the indicated plastic locating tab on the adapter connector that mates with the midrange speaker.
- Connect the adapter connector to the midrange speaker, as illustrated.
- Connect the rotating tweeter's two-wire speaker connector to the small connector on the adapter harness.
Connector modification: The source photographs show the locating tabs to be trimmed but do not specify trimming dimensions. Confirm the connector version and the exact plastic feature before making that modification. No electrical-terminal cutting or repinning procedure is supplied.
3.4 Connect the motor harness and refit
Read the source photographs from top to bottom:
- Identify the rotating tweeter's motor-wire connector.
- Mate the adapter with the factory door-control connector No. 6 that was unplugged earlier.
- Insert the motor-module main harness between the factory connector No. 6 and its door-control module connection, as illustrated.
- Connect the motor module's small connector to the rotating tweeter's motor-wire connector. The next photograph shows this connection to the small connector on the motor-module harness.
- Position and secure the motor module as shown.
- Arrange, wrap and secure the wiring, refit the door trim and test the rotating tweeter functions. The last source photograph shows the front door restored for the function test.
4. Troubleshooting
- Tweeter lighting does not illuminate: Check the lighting-wire connection and inspect mating connectors for bent or backed-out terminals. Check whether the lighting module operates normally. Swap the tweeter and lighting module in turn to identify whether the fault is in the tweeter lighting assembly, wiring or module.
- Lighting colors are incorrect: Select red, blue and green individually in the ambient-light settings. Check the lighting wiring for short circuits or cross-connections between the red, blue and green wires, and for open circuits causing a missing color. Swap the tweeter and lighting module in turn to identify whether the fault is in the lighting assembly, wiring or module.
- Tweeter does not rotate out when the ignition is switched on: Check the motor-wire connection and inspect mating connectors for bent or backed-out terminals. Check whether the motor module operates normally. Swap the tweeter and motor module in turn to identify whether the fault is in the motor, wiring or module.
- Tweeter movement is reversed when the ignition is switched on or off: Check the motor-wire connection and the terminal order in the mating connector. The source body does not supply the required pin order; confirm it from the applicable kit wiring information before changing any terminals.
- Tweeter produces no sound: Check the speaker-wire connection and inspect mating connectors for bent or backed-out terminals. Check that the factory front-door midrange speaker operates normally before the adapter connection, then compare results to distinguish a wiring fault from a speaker fault.
- Factory door functions are abnormal: Check that the door-control adapter connections have been correctly restored. Inspect the factory connectors for terminals that backed out during removal/refitting and for short or open circuits.