Maybe easier to just check all the terminals one by one.
Then use the diagram to check anything that looks bad and you want to know what it does and what it connects to.
Don't let all those lines/wires scare you.
It's actually organized even though it looks like spagetti.
This is for a '69 Dart, but your 69 Barracuda will be similar.
There are three bulkhead connectors:
One with cavities A-H is mostly for the windshield wiper.
The middle one has the main circuits; alternator supply, battery, run, etc.
The last is mostly lights.
So for example knowing that, and wires marked V relate to the wiper, we can find most of them terminating at the wiper switch.
The middle connector is a little tricky because R6 joins others at a welded splice that is hidden under the tape. So to figure out where R6 goes, look at the splice in the diagram.
R6A goes to the ammeter.
J1 goes to the ignition switch
L1 feeds the headlight switch B1 terminal
Q3 feeds a couple circuits in the fuse box
H1 is for the hazzards
The ones that in my experience are the most problematic are connections at headlight switch, and the alternator feed at the bulkhead connector. Followed by the battery feed at the bulkhead connector. Sometimes the headlight dimmer connectors get wet, and some folks have had problems with ammeter connections - although not so much with the rally dash. Still make sure the studs are good, the ring terminals connections are good, and insulated. I've had some issues with the ignition feed on my 67, but more on the engine compartment side.
