12V Wire To 3 Post Isolator Solenoid Missing

[87Itasca]

If the 3 post battery isolator solenoid does not have a 12V switched wire hooked up to its center post, will it work at all?  If not, will that affect the 12V circuits in the coach, or would it only affect the charging of the batteries?

I ask this, because mine does not have a 12V switch wire going to it. It has been removed, and I have no idea what it's been wired to. If I have to add a wire, does it have to be fused for a certain amperage?

I have had an issue where some of my 12V appliances will not work unless the ignition is switch to ON (or the engine is running) and the battery switch is set to DUAL mode. I have not had time to track it down yet, and didn't know if this might be my cause.

[bluebird]

It has to have a control 12v for it to work, and it should be coming from your switch. It should be fused before the switch. You need to investigate why it was disconnected. Maybe it is bad, but it won't connect the battery sets together without being activated.