Alternator / Isolator problem. No juice

Hey all. I put in a dual battery system this weekend. I used an isolator to hook everything up, but it the alternator is not charging the system. So I bypassed the isolator, and just ran one battery, and everything is fine.

So I talked to the Powermaster tech people today...

The guy said that my isolator would not work unless the two wires (that connect via a pigtale to my alternator) were working properly. He said one wire should be hot all the time. The other should be hot when the ignition is turned on.

I checked, and the red wire has no current at all...ever.
The yellow wire has current when the ignition is turned on, but thats it.

Can anyone help me out on this?? please???

DUFFER
'88 4.0L


btw...I crosss posted this to jeepsunlimited...Haven't had any responses from there yet...

bump