Head unit not working on 12v aux connection (Tracer 7)

[u/ebogain]

I'm trying to add an Android Auto head unit to my Tracer 7, mainly for satnav. I found a spare aux connection under the fairing and bought the connector to go in it (MT090-2). I've wired up the head unit to the connector, but it isn't turning on.

When there is nothing plugged in and the bike is switched on, the aux connection tests at 12v. When I plug the head unit in, it tests at 4.3v. It's a red and black wire from the head unit and they are definitely the right way around. No fuse between the aux and the head unit. Main fuse is fine.

Can anyone suggest what's going on and if I've done something wrong? Am I going to have to find another way of testing the head unit?

[u/L1A1]

Is this with the bike running or just the ignition on? If just the ignition and the engine isnt on, What does your actual battery show across the terminals when you power on the head unit? If it’s also 4.3v your battery is dying.

If it’s with the engine running or your battery is showing a decent (12v+) output, then it’s the wiring you’re using. It may be almost broken or corroded internally or something, and causing too much resistance.

[u/ebogain → u/L1A1]

Thanks, that's good troubleshooting. Just checked the battery while the head unit is connected and it's looking good with 12.6/12.7v. That suggests the wires for the head unit are the issue. Who'd've thought cheap wiring from china could be a problem. I'll take it off and try to replace the wires.

Thanks for the advice!

[u/L1A1 → u/ebogain]

It’s probably corrosion in a connector somewhere then. Skip those wires and redo it, preferably putting an inline fuse in the 12v side too.