This is in the Pajero, when the lights are off everything works as it should. It doesn't have a standard ISO connector though so I had to manually splice everything (can get pictures if needed) in order to install the BOSS HU (BV9740) from the Seicento. What might be the cause of this?

Maybe you have spliced into the same loom as the Lights?

I took all the connections from the original HU's power/ground/ignition, not gone anywhere near any other wiring. Even if I had spliced into the lighting circuit though, surely the HU would turn off with the lights off (and on with the lights on), rather than vice-versa?

Unless it was wired backwards :/

smokeyjoe03 said:

Unless it was wired backwards :/

Click to expand...

I can't figure this one out at all so figure I'm just going to run a new live directly from the battery. Obviously the vehicle fusebox has a 15a fuse for the stereo, so should I fit the same in-line, or will the fuse in the back of the HU suffice?

Sorry been thinking and cant come up with any ideas. Yes use a 15amp fuse. The fuse on the car is to protect the wiring. The fuse in the init protects the unit.

Kind of embarrassing but turned out to be completely my fault - what I thought was the earth turned out to be a switched live from the lights, so of course when the lights went on there was no longer an earth. No connection from the old HU was an earth (because there were none left after eliminating +ve +ignition +lights +remote and the speaker connections) but the 'cage' for it is connected to the chassis so I can only assume that it earthed out that way, so I've done the same and it all works fine now

Glad you got it sorted.