Cut off the old radio’s plug and use crimp connectors. Match as follows:
| Car Wire (Astra G) | Function | Aftermarket Radio Wire | | :--- | :--- | :--- | | Brown (A7) | Ground | Black | | Red/Black (A8) | Permanent 12V | Yellow | | Red/White (A4) | Switched 12V | Red | | Grey/Red (A6) | Illumination | Orange/White | | Blue (A5) | Antenna Remote | Blue or Blue/White | | All speaker pairs | Speakers | White, Grey, Green, Violet pairs | Looking at the BACK of the car’s radio connectors (wires exiting away from you): BROWN CONNECTOR (Power) BLACK CONNECTOR (Speakers) ┌─────────────┐ ┌─────────────┐ │ 8 7 6 5 │ │ 8 7 6 5 │ │ 4 3 2 1 │ │ 4 3 2 1 │ └─────────────┘ └─────────────┘ opel astra g radio wiring diagram
| Pin | Wire Color (Typical) | Function | Notes | | :--- | :--- | :--- | :--- | | | Red/White | Switched 12V+ (Ignition) | Turns the radio on/off with the key. | | A5 | Blue | Antenna Remote (12V output) | Powers electric antenna or amp turn-on. | | A6 | Grey/Red | Illumination (Dash lights) | Dims the radio when headlights are on. | | A7 | Brown | Ground (Chassis) | Connect this securely to the new radio’s ground. | | A8 | Red/Black or Yellow | Permanent 12V+ (Memory) | Keeps radio presets and clock alive. | ⚠️ Warning: Some Astra G models (particularly 1998-2000) had a reverse polarity on the illumination wire. If your dash lights flicker after installing a new radio, swap the A6 wire. Connector B: Speakers (Usually Black) This connector handles the four speakers. The Astra G does not share common grounds; each speaker has its own positive and negative pair. Cut off the old radio’s plug and use crimp connectors