Twoxentrix, ah, thanks for providing the numbers, I didn't realize how heavy the audio system is on power, and you're right about it being disruptive at camp anyway. I haven't taken the van out on its first trip yet (in two weeks!) so I haven't experienced practicality... Yet. Battery powered Bluetooth speakers makes much more sense.
It has been a while but this is what I believe the SMB switch looks like. It should be straight forward, 85 and 86 could be swapped with no issues. If there are any other aftermarket items like an amp, that would could cause issues, as it would depend where the amp gets power.
2008 GMC 3500 SMB
Linear Mode
