Junction block wiring on fire wall.

Electrical problem
1987 Chevy Truck V8 Two Wheel Drive Automatic

I have no SES light. I have done the diagnostics and have no 12v power to ECM terminals C16 and B1. (I do have power on A6).
I have checked ECM B fuse and it is OK however I do not have 12v at the fuse holder? Nor do I have Horn/Dome or Lights, tail and park. All these fuses are OK and are on the left side of the fuse box (Which is the Batt side which I think should be a permanent 12V). This is telling me that I may have a feed problem to the fuse box. Can anyone tell me where the feed is to the fuse box and what color wire should it be?
I have checked the wires from the convenience center and they are OK. I have also checked for 12v down line from the fusable link and that is OK (if it is the black lump in the wire from the convenience center!)!

Thank you for your reply.
I do have ignition power to fuse box along with accessory power, just no permanent batt power!
(I do not have the optional factory two batteries).
There are only two pos wires to/from the starter solenoid (not including the switch wire). One goes directly to the pos batt post (thick), the other goes to the convenience center (medium) neither appear to have a fusable link!
There is no apparent alteration to the wiring harness.
I do not have a wiring diagram but in supposition I think that the two wires that leave the convenience center are as follows. I medium thickness RED wire goes towards the passenger side and eventually terminates at a relay on the A/C evaporator.
The other is a medium thickness ORANGE wire with a black "lump" in it about 4 inches from the convenience center with the #16 on it. This is the wire I THINK maybe takes battery power via the big connector through the firewall to the fuse box.
I do have 12 volts in this wire about an inch down line of the "lump"
Are you able to confirm I am on the right track?
Thanks again,
Ric

Thanks for you help guys but I have found the problem! What was confusing to me was the second wire (with fusable link from the starter) was not there. From all the research I did it should have been. On the Diesel and I think 454ci this power lead went directly from the battery + to the alternator. It must have done with this one as well although it is a 350ci. I did find someone else on th internet with the same problem, sound like some may have come off the production line like this. When we got this truck it had no engine so we put a 92 TBI in it with some electical modifications but the pos battery cable was not with it so we used the one that came with the 92, this went straight to the convenience center. Truck is now up and running!
Thanks again,
Ric

Can I merge two into one? Ignition to starter wire fried, would like to know where in fuse block safe to put a bypass for jump, already ran one thru firewall from starter, and when truck is running if you step on gas pedal, the manual shifter from floor slams forward and when you let off pedal slams back. What should check?

Wire harness to transmission was pulled loose, and wires shorted together, now it only has 2nd and 3rd gear. Also when a scanner is plugged in, it will not recognize the ECM. The truck will start and run, but only has 2nd and 3rd gear. I think there may be a blown fuse, but the only fuse box I can find is on the lower left side of the dash, and all the fuses in that box are good. Is there another fuse box on the truck somewhere, or is there another problem?