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?

[Charmander21]

It’s an active subwoofer, so takes power from the cigarette lighter tap. It’s fused with a 10a fuse, and grounded on to the chassis.

Here’s my attempt at a diagram:

The sub can take speaker level input, it has a toggle switch to allow switching between rca and speaker level.

[Paul-R]

How do you join the inputs from the two tweeters to the sub?

[Charmander21]

I’ve used wago 221 connectors, to join to the sub audio input cable. The input cable then slots into the sub with a locking connector.

I was going to solder but wanted to check everything was working first.


Here’s the pioneer wiring diagram:



The difference in line is that rather than wire the speaker output from the head unit, I’ve wired from the tweeters.

[Tr7v8]

Did you connect the two tweeter connections together. That maybe your problem, I suspect the head unit is not happy having different outputs connected together.

[Charmander21]

Hmm it’s possible touched them together accidentally yeah. They don’t actually touch as part of the wiring though. Does anyone know how to get audio back? Or would the head unit start up output again if it doesn’t any longer detect a fault?

[Paul-R]

Did you connect the two tweeter connections together. That maybe your problem, I suspect the head unit is not happy having different outputs connected together.

That's exactly what I was wondering.

[Charmander21]

As mentioned I may have accidentally touched the L + R speaker connections together during the install process. But they aren't connected together at the sub, there are separate L and R feeds into the sub.
Anyhow, I've since disconnected all the sub wiring but there's still no sound. I'm guessing I'll need diag-box access to unlock the audio?

[Clackers]

Hi Charmander, I have recently done the same, I used a Dynamic sounds wiring loom to connect a LOC (RCA converter) to my NAC 4 infotainment speaker outputs, the LOC has a power feed to it and is supposed to provide a remote out to the amp/sub. I assume the remote out is connected to one audio channel as when connected after a few mins i would lose audio to one side.
Googling shows that the infotainment is checking the impedance connected to the speaker outputs all the time and shuts them down if it goes out of spec. If you have a OBD reader you can see when the audio channel has tripped. It can be reset with the OBD reader I Used an Autel MAxi AP200. I would guess it comes back if you put the speaker wiring back to oem but no idea how long that might take, I'd like to think Off & Back on or maybe a reset of the audio system?
I have now bought a new alpine underseat amplified sub which has rca and loudspeaker inputs, which hopefully wont upset it.

[Charmander21]

Thanks for your reply Clackers - I was able to see the errors that I think caused this on the BSI module:

B1501 1A and B1502 1A - Front right and front left output Status Permanent
Characterisation of the fault Low impedance

I think this is where I may have accidentally shorted the speaker wires during the install. I've cleared the codes and they've not returned, but neither has sound unfortunately. I suspect I might have to get into this module: (it doesn't have any listed errors but perhaps needs resetting?)

Audio-navigation system/connected audio system controls, CRT_UDS_KOSTAL - but I get a missing script error on my Lexia.

[Charmander21]

Ok I downgraded to Diagbox 9.85 and was able to enter the NAC ecu module and clear the impedance related codes. Sound is back!