Fuse panel

[strategic90]

I have 1989 suburban V1500, 350 gas engine. There's an auxiliary battery set up on the is truck that has a wire (black w/white stripe) going to the "S" side of the solenoid from the area of the fuse panel that is marked as "ACC", has three ports there, one of which is the black wire with white stripe.

My question is this, should ACC buss be powered with key on? There is no power there now, if there is supposed to be power with key on, where does power come from to power up the ACC buss? The power supply location, if on the engine compartment side, would be appreciated.

Previous owner may have put this auxiliary battery in or paid someone to install because the solenoid is not a continuous duty solenoid.

I powered up the "S" terminal to get the solenoid to trip, nothing, I'm assuming that solenoid is not good...

Thanks in advance for help.

 

[75gmck25]

It was probably wired differently on a the '89, but my '75 Camper Special has the factory 2nd battery option and it uses a relay mounted on the driver's side inside the fender. Its a relatively small relay, since it only has to handle the charge output from the alternator.
- From the power junction next to the brake booster there was a 10 gauge wire with a fusible link that ran over to the relay on the fender, and then it had another power wire from the relay over to the battery positive. Battery negative was grounded to the body/frame.
- From the fuse box there was a power-on (18 gauge?) wire to activate the relay

Ignition On - relay activated, so the power junction was connected to the battery, and the alternator charged the battery.
Ignition off - relay disconnected the battery from the power junction and isolated the battery. This allowed you to power the camper while parked, but only draw from the aux battery.