Circuit 62-18 is the feed from the HLS to the gauge lights. Its hot in both switch positions. It runs to a panel light gang connector where it gets distributed in the following ways...
62A-18 feeds the left side courtesy light on the bottom lip of the dash when the HLS knob is rotated.
62B-18 feeds the OIL/TEMP gauge connector, specifically the far left hand pin position of the top row.
62C-18 feeds the heater panel light.
62D-18 feeds the ALT/FUEL gauge connector, same as before, far left pin, top row.
62E-18 feeds the right side courtesy light on the bottom lip of the dash when the HLS knob is rotated.
62F-18 goes out through the firewall down and up through the plastic auto trans shift console to light the shift indicator window on auto equipped models.
62G-18 feeds the SPEEDO gauge connector, only this time it is the far left pin of the MIDDLE row.
Every one of those bulbs needs a ground to work. 11C-18 grounds the OIL/TEMP light via the far left pin, middle row. 11B-18 grounds the ALT/FUEL light via far left pin, middle row. Both wires originate from the same dash fastener. The ground for the speedo lights is provided via housing contact with the dash. No wire feed to the gang connector in this case.
If you've never had those gauge clusters out before to examine them, there are a couple things you should know. First, the battery should be disconnected before you attempt to remove the ALT/FUEL cluster, as the Ammeter is wired in series with the battery, so both of those gauge terminals are always hot. The dash is of course solid metal. Metal everywhere with exposed hot wires nearby is an invitation to arc weld, which can fry your gauge and let the magic smoke escape from your wires. Only after that gauge cluster is out and the ammeter terminals are positioned safely away from the dash metal should you reconnect the battery. Take the same precaution when you go to replace that gauge cluster back in the dash.
Next, the male pins for the instrument and light feeds are crimped to the printed circuit boards (PCB) and are extremely fragile and delicate. Great care must be taken when removing the plastic female connectors from those pins. Slow is smooth and smooth is fast. I like to use a thin blade screw driver to carefully work the plastic piece up evenly around the perimeter. Just don't let it get cocked to hard in any direction. Once free, gently feel and examine the pins to see if any are loosy-goosy. Loose pins can be tightened up with some strategic hot solder application. The PCB must first be removed from the back of the gauge housing for that job. If you do have to lay some solder down, just make sure that it doesn't form a bridge between any two pins.
If the copper traces in the PCB's are tarnished and yucky, you can shine them up with a pencil eraser. Just don't use anything abrasive, like even fine grit sandpaper. The stamped steel nuts that secure the gauge posts to the PCB are prone to vibrate loose over time, so its a good idea to check them for snugness while you can. The black plastic light bulb holders are a tension fitting with the PCB and can be rotated to a free position to examine/replace the light bulbs. The holders have delicate brass contact tabs on either side, one for POS and one for NEG, that must be in contact with the copper traces of the PCB when secured in place. There bulb filament has no polarity. It can be inserted into the holder either way, and the holder can be inserted into the PCB either way, as long as one brass tab is in contact with a NEG copper trace while the other is in contact with a POS trace. Its just a completion of a circuit.
Now, if you're feeling extra froggy, you might want to venture where not too many men have gone before. No doubt you'll notice that the metal gauge housings are painted blue. Blue isn't exactly the most reflective color in the spectrum. What myself and a few other folks have done, is carefully pry up the metal tabs that retain the plexi-glass covers so that we could completely gut those housings. Chrome/silver or even white spray paint is far more reflective than blue. Its like having bulbs that are ten times brighter, yet they're the same puny, little bulbs. Its an amazing difference. Why IHC chose to paint the hosuings blue is a real head scratcher.
