Hey guys. First post. New to samurais, but pretty active with 66-77 broncos.
I'm building a samurai with my son for his first truck. It's an LJ-80 body that we are putting on a 1991 frame and running gear. The LJ was previously on an 86 frame, so some of the work has been done for us.

The 91 I bought was throwing code 33 when I got it.  I verified the MAP ref voltage was out of range from the ECM, had the ECM rebuilt and now it shows code 12, which is good. Here's the problem.

My fuse block does not have the spare spot to force diagnostic mode. I do have the 4 pin connector in the engine compartment, passenger side by firewall, but no jumper is installed. How do I pull it out of diagnostic mode? If it matters, I also don't believe I have the "service required" toggle switch, and believe me I have pulled stuff apart around the column looking for it.

Canadian truck if it matters. Was there crossover years where things were in-between? What am I missing? I want the 91 to be right before I pull it apart, and this I the last thing.

FWIW, the truck will be a 91 completely other than the body. The harness, ECM, gauge cluster, etc will all be grafted into the 79.

Thank for any help. If I've posted in the wrong spot, my apologies. I'll move it of mode can.

Mike.