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I've had the dash apart and have recrimped the connection - it's definitely good. So what else could be causing a lack of sound?

Lack of power to the amp, no turn on signal (emote) to the amp, no audio signal to the amp.

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I've no idea if the amp is powering on or not - there doesn't seem to be a way to check, but I'm guessing it's not.

I tried to check for some sort of voltage on the blue wire when turning the headunit on, and there didn't seem to be anything coming from it at all.


Sounds like the HU remote out is broken... but let's check the basics:

Power: Take a voltmeter and measure across the power supply terminals (B+ and Ground) and make sure you've got 12V there - if not, check power wires, fuse(s) and ground attachments.

Remote: With HU on, measure across the remote terminal and ground on the amp. If not 12V there the amp will not turn on. If there isn't, try disconnecting the remote wire from the amp (insulate it just in case) and temporarily connect the remote terminal to the B+ terminal (should turn the amp on permanently, so don't leave it like that after testing). You could also try measuring between the remote wire and ground (both on the radio and back by the amp) with the wire disconnected from the amp, just in case the amp is broken and pulls the voltage down to ground. You could also check continuity/resistance between the remote wire and ground (so it's not cut through and grounding out somewhere)

Audio signal: If the above doesn't give you sound, try another signal source, like a portable player with adapter cable (3.5mm to RCA).
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/Michael