With the preliminary tasks taken care of in the wiring of the Elco, I picked a target area to start my rewiring. Since the dash frame was in place, the first target circuits I chose were the wiper circuit and headlight circuit. For all intents, these two circuits are two difficult circuits to map out and get wired since the wiper motor typically has four wires on its plug while the headlight circuit, especially when rewiring for a different configuration, has the added difficulty of trying to figure out what wires on the headlight sockets go to power in, high/low beam, ground, or whatever. There's also the matter of figuring out which wires on the headlight switch go where, same as the wiper switch. The wiper switch may typically have four wires on it as well, especially with those that have the integrated washer motor switch. As for the headlight switch, since I always wire this circuit to turn everything on at once, with the high beam being operated off of the standalone switch typically present, I only need to use the headlight switch as a regular on/off switch.
Starting with the wiper circuit I started ohming out the wires to see which ones get continuity in the different switch positions. It took me a little playing around and going in circles, which was stupid on my part because I could've gotten steered in the right direction from the start if I had just researched for a wiring diagram/schematic. Upon doing this I found that power actually comes in at the wiper motor on its terminals, with a power feed going to the washer pump, which is integrated on the wiper motor assembly. The switch wires all go to the wiper motor, with no wire going to the fuse box. On the switch, according to the diagrams, it had three wires that switched the wiper motor and activated the washer pump. The fourth wire was a ground. Running all four of these wires through the firewall to the wiper motor, I terminated the ground on a terminal secured to a screw in the firewall. With the other three color coded wires hooked up to the three wires on the wiper motor, I ran the power feed wire back through the firewall and hooked it up to one of the terminals on the fuse box. With the wiper motor circuit taken care of, the fun part began, the headlights. Even though the H4 configuration headlights share the same plug as the older style headlights on these cars, the pinout is way different. The H4's utilize a switched ground concept where a single power feed goes into the light and the high and low beam selection is done via switching grounds on for either side. Because of this, the plugs have to be completely rewired from their original configuration. Since the plugs on this car were dry rotted, I had to replace them with some fresh pieces, well I had two new plugs and two salvaged plugs that were still in good shape. I ended up having to use the 69 Mustang as a reference for the pinout of the plugs since I rewired that car for H4 LED headlights a good while back. With the new pinout figured out, I went to work wiring up the left side of the headlight circuit. On the wiring harness going to the lights, the ground wires that were secured to the chassis ground were hooked up to the ground for the low beam lights. Contrary to what I said, I figured out a way to do a hybrid wiring setup for this crap. First things first. The headlight switch on the dash, being a simple on/off switch, will be used to switch an automotive relay, as I've done on previous wirings. Power was routed from the fuse box over to the switch and out from the switch to the automotive relay. The other side of the relay coil was routed to a terminal grounded on the firewall. As for the switched contacts, an inline fuse was hooked up to one side of the relay to feed power in from the battery while the other side of the relay will send power out to the power in terminal on the headlight sockets. While this power will feed both high and low beams, only the ground for the low beam is on a constant hookup, making the low beam lights a switched power circuit, not a switched ground circuit. Now for the high beams. Since this car has a floor switch with three wires, I had to isolate two wires, using the floor switch as a simple on/off switch, just like the dash headlight switch. After getting my two wires and hooking up some extra wire of the same color to reach out through the firewall, I got to work on the outside. I did have to drill an extra hole in the firewall near the fender shield so I didn't have to run too much wire to go to the middle of the firewall then back to the fender shield. With that little bit of business out of the way I started concocting how to do the high beams. This involved taking the other headlight plug and hooking up the 12v feed, which taps off the low beam 12v feed, which is switched via the automotive relay. From here I took both the high and low beam grounds of the two remaining terminals and wired them together, then spliced into the wire from the high beam side on the primary low/high headlight plug to add that high beam circuit to the mix. The high beam only light socket will switch both sides of the light on at the same time in high beam mode while grounding the high beam side of the primary lights as well. This ground wire for the high beam on the primary light, still in the wire harness, was isolated on the cut off end and spliced into one of the wires going back to the floor switch. The other wire on the floor switch was terminated with a terminal on the firewall. This provided the switched ground for the primary light's high beam and the complete switched ground for the high beam only lights. In essence the high beam light circuit has two switches in the circuit, the one that switches the 12v that feeds everything and the ground that completes the circuit for just the high beams. I ended up spending a greater part of the day getting all of this figured out the way I needed it to be for it to work, so I only managed to get the left side done before it got too dark. Of course the right side of the headlight circuitry will just be a duplicate of the left side, using the color coding of the wires as reference to get the right side wired up just the same. I did take advantage of a wire snake to cover up the bundle of wires going back to the firewall so I can save on zip ties. There were several extra wires that weren't used in the harness however. I know that one or two of these wires are for the side marker lights on the front fenders. I'll wire these up to the 12v line feeding the low beams as these will come on at the same time with the low beam lights. Once everything is figured out, any remaining wires will be cut from the harness to keep things less cluttered. As for the taillights, I will have to hook up the light sockets on the rear bumper to the harness going back into the cab then put power on the wires to see which ones light up the four taillights at the same time. Once I get that line mapped out I can run a line over to the output side of the headlight switch in the cab. Instead of hooking the taillights to the main headlights, the taillights can be hooked to the fuse box, saving on the amount of wire to be run as I won't have to worry about running wire out to the engine bay to hook up to the side of the circuit working off the automotive relay. Of course with the conclusion of the headlight circuit wiring, this allows me to fall right into the gauge cluster/brake lights. Since I'll have the rear lights plugged up, I can then get the brake lights hooked up, along with the turn signals in the dash and outside. I also managed to fish out a single DIN radio shell left over from another vehicle, stored in the trailer, that can be used for getting the radio mount set up in the dash. I also had a triple gauge cluster on the shelf in trailer that I can put to use. This gauge cluster was an online purchase and even though it has a voltmeter versus an ammeter (which I do not want), the oil pressure and temperature gauges are in the metric system. The temp gauge is in Celsius and the oil pressure is in whatever unit of measure for pressure in the metric system. Only solace I can take from these gauges is the idea that the displays are marked by scale so even when I don't know exactly what the measurements are, seeing the needle in the middle to high for the oil pressure would be a good thing and the middle to low for water temperature would also be a good thing. Its nice for me to be able to have a lot of the stuff in house to get the wiring done on the car, including battery cables, flasher relay w/plug, and plenty of wiring salvaged from old wiring. As I progress and eliminate circuits on the car, the wiring job will get that much simpler as there will be less circuits to sort through.
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