I am looking at the wiring diagram for my 68 Chevelle. I see wires with certain color codes going into the bulkhead connector from the interior. Then I look at the engine compartment diagram, and wires coming out of the bulkhead connectors are different than the wires going in at the same point in the connector. Am I reading the diagrams wrong? Is there a corresponding out wire in the engine compartment for every in wire from the the inside?

Am I making sense?

Kevin

Yes, there a corresponding out wire in the engine compartment for every in wire from the the inside. A little confusing.
Think of the connector in the harness as looking down on the face of the pins. Then looking at the fuse panel side as looking down on the sockets.
If you "mate" up the empty pin and socket holes (no wires), should see that most everything matches color wise.

It makes sense to me. On my 74 Nova I added a factory tach and was cheap and didn't get the correct harness' so I traced down the diagram and used what terminals or location in the bulkhead that it called out for to do certain things and then took wires and terminals out of a donor harness to make it like factory. I also remember something like what you have (one wire on one side but not the other) and it's probably due to options with one harness being able to do two things on the one side of the bulkhead but one harness on the other side that could be missing a terminal or wire.
Also look at the diagrams closely and most are numbered terminals and on my facotyr wiring diagrams the plugs are next to each other and are mirror images (left top corner on the one goes to the right top corner on the other plug).
You may also have a harness that someone has messed with or maybe used the wrong engine side harness or interior harness or maybe from different years.
Jim

Funny you ask this. I just went through the same thing the other day. Pull the bulkhead connetors away from the fuse block and look down at the connector toward the inside.This should be with the wires coming out of the connector at the underside of the connector and male side of the plug staring up at you. This is how it is situated on the schematic. I hope this helps..