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      11-11-2008, 03:57 AM   #39
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United Kingdom

Drives: 335i m-sport LCI
Join Date: Jul 2006
Location: UK

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Originally Posted by robbie99 View Post
Yeah, that's a about it.

Good question about if the existing cables are labeled. They aren't . I was lucky enough to choose working on the driver's side first. On this side it was easy to find where the existing wires were connected and you could visually determine which wires were going to the subwoofer, to the headunit (via under the front of the seat) and to the door speakers (towards the front). The wiring was as shown in the install instructions.

On the passenger side however it was a bit more difficult. The connections were further forward and the existing wires were included in a much larger loom. It was impossible for me to see which pair of wires were from the headunit and which were from the subwoofers. They all had the same colour code so I had find way of determining which wires were which.

This is what I did.

1. Find and expose the two connectors.

Each connector will have three wires leading into it. The three wires will have the same colour code. For the passenger side, the wires will be either blue with a white stripe or blue with a brown stripe. The white striped wires are the positive ones, the brown striped ones are the negative ones. (The wires from alpine amp will also have either a white or brown stripe.)

2. Pick a connector (positive or negative) and snip one of the wires. Switch the radio on.

If door speaker works and subwoofer doesn't then the wire you snipped is the subwoofer wire. If door speaker doesn't work and subwoofer works then the wire you snipped is the door speaker one. If both door speaker and subwoofer don't work then the wire you snipped is from the headunit.

3. Label your wire. I used masking tape.

4. Join the snipped wire back to the connector. (using masking tape again!)

5. Back to step 2 - snip a different wire to determine which one it is.
Brilliant - thanks for that. Bit like 'mission impossible' trying to work out which wire to cut.

Just need some dynamite and a countdown timer.