No Sound after subwoofer install

[Charmander21]

Hi All,

Vehicle details:
Citroen Dispatch Driver 2020 2.0 BlueHDI, Manual
VIN: VF7**************[VIN obfuscated, can be read by forum staff]

I beleive this van has the NAC head unit? it has a touch screen with navigation and wired carplay/android auto.

I recently replaced the door speakers and tweeters on my dispatch van, this worked no problem. I also tapped both tweeters (before the crossover) to provide a feed for the sub (Pioneer TS-WX140DA) As I didn't have time to connect the sub at this point I left the cables for the tap unconnected to the sub, and the sub unpowered. At this point everything was functioning fine, audio through all connected speakers.

However at some point when I connected up the sub, to the speaker taps, and attempted to power it on (using a piggyback fuse tap from the cigarette lighter fuse) after restarting the van, I've lost all audio, although the headunit appears to function absolutely fine apart from this.

What I've tried:
> Disconnected the subwoofer from the speaker taps and power.
> Checked all relevant fuses - as far as I know the 20a head unit fuse is the the only fuse for the head unit and amp?
> BSI reset procedure
> head unit reset by holding down the phone key

I have a diagnostic tool but I don't think I can access the audio module.

Is there any thing else I can try? Thank you.

[mickthemaverick]

When you repkaced the doot speakers did you match the impedance ratings with the originals?

[Charmander21]

The door speakers and tweeters were replaced with alpine SXE-1750S - The impedance is 4Ω and I think that matches the factory speakers. I'm not sure if it was obvious from my post but these were wired in and working fine, it's when I tried to add the sub that something went wrong.

[mickthemaverick]

Can you draw and post a wiring diagram of how you connected the sub to the tweeter taps?

[Paul-R]

Is it a passive or active subwoofer?