Fuse for retained accessory power (RAP) and when the command power button is pressed.
Thread Starter
MBWorld Fanatic!
Joined: Nov 2003
Posts: 2,413
Likes: 497
From: Earth
2015 C300 4Matic Sport
Fuse for retained accessory power (RAP) and when the command power button is pressed.
I recently installed an Audison Prima AP8.9 bit DSP amplifier in my C300. 
(DIY instructions soon)
Everything works great. The Audiosn amp turns on/off with the factory amplifier using DC offset and a remote trigger provided by a PAC TR4 remote turn on module.
I also have a JL Audio Fix 82 in the chain to flatten the factory signals and feed the Audison via optical.
The Fix 82 remote turn on is currently connected to fuse #446 (in the trunk) which only has power while the ignition is ON OR right after ignition is turned OFF (if the drivers door has not been opened). This is called retained accessory power or RAP.
Everything works great so far except I got in the car today (ignition off) and pressed the power button. The command came on, but the Fix 82 did not.
it appears I need to tap a fuse with both ignition power and when the power button is pressed to turn on the command system.
Does anyone know which fuse number will do both of these things?
(DIY instructions soon)Everything works great. The Audiosn amp turns on/off with the factory amplifier using DC offset and a remote trigger provided by a PAC TR4 remote turn on module.
I also have a JL Audio Fix 82 in the chain to flatten the factory signals and feed the Audison via optical.
The Fix 82 remote turn on is currently connected to fuse #446 (in the trunk) which only has power while the ignition is ON OR right after ignition is turned OFF (if the drivers door has not been opened). This is called retained accessory power or RAP.
Everything works great so far except I got in the car today (ignition off) and pressed the power button. The command came on, but the Fix 82 did not.
it appears I need to tap a fuse with both ignition power and when the power button is pressed to turn on the command system.
Does anyone know which fuse number will do both of these things?
Junior Member
Joined: Aug 2019
Posts: 49
Likes: 17
2018 C300 Sedan
I recently installed an Audison Prima AP8.9 bit DSP amplifier in my C300. (DIY instructions soon)
Everything works great. The Audiosn amp turns on/off with the factory amplifier using DC offset and a remote trigger provided by a PAC TR4 remote turn on module.
I also have a JL Audio Fix 82 in the chain to flatten the factory signals and feed the Audison via optical.
The Fix 82 remote turn on is currently connected to fuse #446 (in the trunk) which only has power while the ignition is ON OR right after ignition is turned OFF (if the drivers door has not been opened). This is called retained accessory power or RAP.
Everything works great so far except I got in the car today (ignition off) and pressed the power button. The command came on, but the Fix 82 did not.
it appears I need to tap a fuse with both ignition power and when the power button is pressed to turn on the command system.
Does anyone know which fuse number will do both of these things?
(DIY instructions soon)Everything works great. The Audiosn amp turns on/off with the factory amplifier using DC offset and a remote trigger provided by a PAC TR4 remote turn on module.
I also have a JL Audio Fix 82 in the chain to flatten the factory signals and feed the Audison via optical.
The Fix 82 remote turn on is currently connected to fuse #446 (in the trunk) which only has power while the ignition is ON OR right after ignition is turned OFF (if the drivers door has not been opened). This is called retained accessory power or RAP.
Everything works great so far except I got in the car today (ignition off) and pressed the power button. The command came on, but the Fix 82 did not.
it appears I need to tap a fuse with both ignition power and when the power button is pressed to turn on the command system.
Does anyone know which fuse number will do both of these things?
Thread Starter
MBWorld Fanatic!
Joined: Nov 2003
Posts: 2,413
Likes: 497
From: Earth
2015 C300 4Matic Sport
Turn on works great however, there is always pop/bump in my speakers from the factory amp as it shutdowns before the fix 82 and Audison.
I've messed with all the settings on both devices to try and fix their shutdown time, but no luck. I even tried using the TR-4 on DC offset and then Audison as the ON/OFF trigger to the FIX 82.
I also investigated using the factory amp as an ON/OFF trigger, but the two fuses feeding the Factory AMP remain 12 volt, even after the car is locked the AMP shutdown/sleeps.
Not sure how the factory amp get its wake up/ shutdown instructions.
I think my solution is to probe the front fuses for one that is 12volt on ignition or when that power button is pressed. If that fails I can probably tap into the command display power.
Thanks!
Junior Member
Joined: Aug 2019
Posts: 49
Likes: 17
2018 C300 Sedan
I originally had the FIX 82 doing the DC offset remote trigger ON/OFF to my Audison AMP.
Turn on works great however, there is always pop/bump in my speakers from the factory amp as it shutdowns before the fix 82 and Audison.
I've messed with all the settings on both devices to try and fix their shutdown time, but no luck. I even tried using the TR-4 on DC offset and then Audison as the ON/OFF trigger to the FIX 82.
I also investigated using the factory amp as an ON/OFF trigger, but the two fuses feeding the Factory AMP remain 12 volt, even after the car is locked the AMP shutdown/sleeps.
Not sure how the factory amp get its wake up/ shutdown instructions.
I think my solution is to probe the front fuses for one that is 12volt on ignition or when that power button is pressed. If that fails I can probably tap into the command display power.
Thanks!
Turn on works great however, there is always pop/bump in my speakers from the factory amp as it shutdowns before the fix 82 and Audison.
I've messed with all the settings on both devices to try and fix their shutdown time, but no luck. I even tried using the TR-4 on DC offset and then Audison as the ON/OFF trigger to the FIX 82.
I also investigated using the factory amp as an ON/OFF trigger, but the two fuses feeding the Factory AMP remain 12 volt, even after the car is locked the AMP shutdown/sleeps.
Not sure how the factory amp get its wake up/ shutdown instructions.
I think my solution is to probe the front fuses for one that is 12volt on ignition or when that power button is pressed. If that fails I can probably tap into the command display power.
Thanks!
