Well, just a quick update on the last fiddly bits for the A/C system. I purchased some shiny aluminum brackets and bolted them down to the inner fender. They'll help keep the hoses from chafing.
Tired of wondering what to do with the old A/C hoses for the rear air unit, I finally removed them completely.
Ever curious about the length of these puppies? Mine measured out to 26' when straightened, plus an unknown length that had been cut when the unit was removed. Don't worry though, I kept them in case of an eventual need.
Wait, what's this here?
That's right, I put the rearview mirrors back on!
Oh, you were wondering about the fact that the lights are on? Yeah, I guess I kinda wired the whole vehicle during the last two weeks as well. If you don't want to read about all of my adventures in Electron Land®, then feel free to skip to the last paragraph. I didn't take many pictures because unless someone explained what you're looking at and could also contrast it with a wiring diagram, the wires all just look like colorful jumbled spaghetti.
You know, like this:
This was it, the big roadblock; that one job I'd been dreading for years.
There were five major wiring groups to tackle:
1. American Autowire Power Plus 18 fusebox and harness (lights, fuses, power to most accessories)
2. Vintage Air A/C harness
3. 1988 ECM harness
4. Compushift transmission controller harness
5. Instrumentation
They were dispatched in that order. I tried to start with the easy stuff. First came the final mounting of the fusebox and unfurling the light harness leads. Headlights, horn, turn signals, taillights, electric fan, fuel pump, fuel tank sending unit and reverse lights started the ball rolling. For the most part the Power Plus 18 kit was very easy to work with (they don't make the 18 any more, but they do sell a 20 circuit Power Plus kit). The instructions were very good and they included a full color wiring diagram for the entire system. Even the individual wires were screen printed with their intended use every few inches. One thing that caught me off guard right away was the fact that there was no provision for a reverse light lead built into the system, anywhere. Instead, I repurposed the wire marked “Third Brake Light” for this task. I'd have thought that backup lights would be a standard inclusion. The rear light wires were routed in the factory style, up through the a-pillar, along the roof and then back down through the d-pillar. The rear harness was just barely long enough to reach the driver side light. I simply tapped into the original passover for the passenger side lights. All but two of the original firewall holes are now filled (except for the three directly aft of the engine, where they're mostly hidden), so the old choke and speedometer cable holes are now a pass-through for the A/C, front lighting, horn and electric fan wires.
The AAW kit is GM color coded and designed for custom installations. Most of the wires were the same colors as those found on my old '70 harness, but the AAW kit didn't include many of the plastic connectors specific to the truck. Keep in mind that these sort of things are included in their Classic Update and Factory Fit kits. As an example, I had to remove the plastic connector for the headlight switch from the 1970 harness (depress tabs on crimped connectors, pull out wires) and plug the new wires into it.
Other plastic connectors that I had to reuse were for the ignition switch, brake switch and courtesy lights. For whatever reason, AAW included the right dimmer switch connector in their kit though. I was lucky enough to already have a tool that could properly crimp the non-insulated connectors included in the kit. To buy the two tools recommended by AAW would have cost approx. $200, but I got away with using a $30 tool that did the job just as well. Those wires are not coming loose, they are very solidly crimped. Just as an example, I had the CD player stolen out of my DD once when I lived in the Phoenix area. I had crimped the CD player's pigtail harness to the original wires from the old head unit with butt connectors and this crimping tool. When the thief yanked out the deck, none of my crimps failed. On the contrary, two wires snapped and most of the pins pulled out of the back of the head unit instead. I love this crimping tool.
Other things I was disappointed that AAW didn't include in their wiring kit: brake warning switch / light wiring, alternator / charge warning wiring, coolant light wiring (the one that's tied into the ignition switch), plus wires to the courtesy lights and cigarette lighter. I simply reused most of those, or cut new pieces of color correct wire from the leftovers of the '88 harness. The windshield wiper motor and switch wiring had to be excised from the old harness and reworked as well, though AAW did provide a fused circuit and power wire lead for the wiper motor.
With those basics completed and functioning (I managed to break my first headlight switch and had to order another one or else I would have come forth with a picture like the third one in this post much sooner) it was time to start routing wires for the Vintage Air Gen IV unit. It came with a dedicated wiring harness and 30 amp circuit breaker. Even though the AAW kit has a fused circuit assigned solely to A/C, the VA instructions told me to place it's power and ground wires as close to the battery as possible. The large, red power wire from the circuit breaker was routed to the positive post on the starter, while I managed to merge the two ground wires in with the main engine harness and firmly attach them together with the ECM grounds on the thermostat housing. Next, there was an easy feed and return loop which fit on the heater control valve. After that I used 30' of blue wire to reach from the interior, passenger side where the Gen IV unit was, across the interior to the driver side, out through the old speedometer cable hole into the engine bay, over the top of the inner fender to the core support, into the plastic wire retainer and across the core support to the passenger side, through a grommet in the core support and finally spliced into the A/C safety switch. Then another blue wire left the opposite end of the safety switch and retraced all of that to splice into the A/C compressor clutch lead in the main engine harness. Hence the need for 30' of wire. The last A/C wire was a small one which spliced smack dab into the ignition switch and signaled the unit to power up when the key was in the 'On' or 'ACC' position.
Let's see, what do I remember of the ECM harness? Well, it already included leads to the coil and starter, so I didn't need those wires from the AAW kit. All I had to do was plug them into the right connectors on the AAW harness and call it done. Though I did get to use the AAW tach wire from the other post on the coil to the ECM and tachometer. There were a few other mysteries though. Eventually, and after finding all of my wiring diagrams I'd printed out years ago, it all started to make sense. Even though I stumbled upon the connector for the Hot Fuel Module, the unit itself was missing. There was another plastic three wire connector adjacent to the Hot Fuel Module which the service manual says is an A/C connector, but the wiring colors don't correlate to anything on the diagrams I've got so it remains a brainteaser in the meantime. The other loose wires and connections which had yet to be made were: fuel pump feed (the fuel pump relay already gets power straight from the battery and has an inline fuse) and ground, auxiliary cooling fan lead from relay, oil pressure sensor lead to instruments, water temperature sensor lead to instruments, fuel injector power to fused circuit, ECM power to fused circuit, heated O2 sensor power (an addition of mine) to fused circuit, a few loose grounds, an ECM to NSS wire and a fused connection to the cranking circuit on the ECM.
After all of that, the Compushift transmission controller was a breeze.
Two plugs simply snap in place on the transmission and the TOSS, which on my rig is at the back of the transfer case. One difficult bit was figuring out how to get those things through the existing holes in my firewall without having to drill any new ones. I wound up taking apart the D-sub connector at the transmission controller side then just barely being able to slide it through a 1” firewall hole (already half filled with wiring) and reassemble it again on the other side. The other connections were switched 12V power, a ground, two wires which spliced into the TPS signal, one which spliced into the RPM signal from the coil and a wire which reproduced the TOSS signal and would feed the speedometer.
Last but not least were the Autometer gauges. They were very simple and straightforward. Even the AAW instructions included a diagram to help hook them up correctly. Many crimped blade connectors later, and it was all in place. I did have to modify the twist-lock turn signal bulb holders though. Since I no longer have a printed circuit board, they needed both power and ground wires which I fed through holes drilled in the back of each one. Oh, the oil pressure sending unit that had been on my engine was the wrong ohm range (needle went straight to 100+ p.s.i. with key on) for the new gauge, so I had to switch it out for the one that came in the Autometer package.
Now I am at the troubleshooting phase. The TPS isn't reading correctly yet (at a constant no matter where the throttle is), the gauges don't light up with the headlights on, I think I've got the fuel pump feed and fuel gauge wires reversed (gauge jumps up to 3/4 tank with key on and fuel pump doesn't engage), the transmission temperature is reading -5° in Fahrenheit, I've yet to mount the auxiliary cooling fan and I still need to remove the steering column to cut a hole in it for the neutral safety switch. Despite all of that, I jammed the big purple NSS wires together and the starter turned the motor over for the first time in 6 years. I will say one thing to end this though, an uncorked 454 dumping straight out through open headers is LOUD! I couldn't resist one quick spritz of starting fluid.