Amp not switching off

[SharkGill]

To clarify I made the incorrect splices but realised before I hooked it all up so had to redo the wiring so no damage caused.

[HPsauce]

Dumb question time. Is there any way of inserting a manual switch into an appropriate circuit to turn the amp on and off definitively.
If so, the next step could be to have a relay to do it for you?

[SharkGill]

I was thinking of a switch mounted on the dash somewhere which I can manage but the whole floating ground and pop on power on/off is also bugging me as I don't have the know how to sort that yet.

[SharkGill]

The test is to connect a multimeter on ohms between the phono ground (outer shell) and the power ground. If you get zero / low resistance then the amp is not suitable. High resistance / open circuit is what you want. I don't know that any manufacturer actually includes floating / chassis ground in their specs though.

Another idea for just a sub is to use a speaker-level converter off the rear deck subs. The Bose amp will be responsible for the crossover then, which is not necessarily ideal, but a converter would likely side-step the floating phono problem.

is this the sort of converter you mean?

Screenshot 2026-06-04 170647.png

[Ronin]

Thats it.
You can see the caps, voltage dividing resistors and 2 small transformers (one channel each) that will step down the signal at a cost of signal degradation, loss of deep bass frequencies and other things dependant on how its designed internally.

It should also have a small flat head variable resitor that you can use to match the input voltage of the subwoofer/amp combo.

[SharkGill]

Hopefully I’ll get round to trying this tomorrow.

image.jpg

image.jpg

[SharkGill]

Wiring in this converter resulted in the same outcome. The switched positive on the Bose does not switch off. Could someone suggest an alternative switched positive I could tap into in the boot? There is another control module in the same area as the Bose amp possibly the Parking sensor module.

[MikkiJayne]

Which wire are you using for the amp control? This is not a common issue, normally the amp control from the head unit just works.

[SharkGill]

White cable listed as switched live, goes to pin 6 on the yellow connector back of the head unit. This was tested with a multimeter and did behave as a switched live.

IMG_0443.jpeg

[MikkiJayne]

Very odd. That is indeed the amp remote from the head unit and normally does turn off with the head unit (or when you pull the key out). Very strange that is not turning off when it should, I've never seen that before.