possible timing advance issue

So, i have a 1992 k1500 with a 5.0 L. I recently replaced the distributor and knew it needed timed again. I went to time it with a timing light, hooked up the timing light and then disconnected the electronic timing advance wire(tan wire with black stripe behind the cover on the firewall) checked my base timing as i was curious of how far off it was. It read about 5 degrees. So i then was also curious as to what it would read with the timing advance wire hooked back up, so i hooked it up and checked it again and there was no change still read about 5 degrees. Now im pretty sure thats not normal, it should advance with that hooked back up correct? If it isnt normal like i am thinking what could be causing this issue, broken wire, faulty ICM....? I am not sure, could someone point me in the right direction please?

Is this at idle, rev the engine see what happens.

That is at idle. So the way i understand it is base time is supposed to be 0 then after you hook the wire back up it should advance itself (at an idle) to somewhere between 4-8 depending on the pickup. Then it will obviously advance the more throttle you give it and the more load you put it under. So if my understanding is correct, with a base time of about 5, after i hook the wire it should advance to somewhere between about 9-14 but it does not just stays right at 5.