audi a3 1.8t quattro preface lift,sub and rear speakers keep cutting in and out

[millwrx]

i know the front speakers are powered by the headunit,i belive the rear sub and the rear speakers are powered by the small amp inside the sub itself,is this right?also why would it be cutting in and out on random ocassions??
anyhelp would help.cheers

 

[AndyMac]

Are you running the stock HU?
If not then it could be a dodgy connection on the remote turn on lead, that turns the rear/sub amp on/off with the HU. If it's a stock HU then it could be an aftermaket one was installed by previous owner and they butchered the wiring, and then bodged it to put the original HU back in when they sold the car.
You need to pull the HU and pot a pic of the wiring behind it.
Is it totally random, or when you go over bumps?
You are correct that the rears and sub run off a separate amp inside the sub. If the wiring looks untouched at the HU then you need to check the sub, which isn't the easiest bit to get to.

 

[millwrx]

stock hu,it goes on and off randomley even with the engine turned off,connections on the back of the set are fine,thinking its the amp inside the sub,are the amps removable from the sub to check.
cheers

 

[AndyMac]

Yes but you have to remove the sub to get to it, it's attached to the front panel, it looks like this:

 

[millwrx]

cheers for that,i have had the sub out before to replace the alarm siren