Electrical - Interior By Jeff Zurschmeide

Of all your wiring issues, getting your interior working properly can give you a pain in the neck -literally. Legendary contortions are often required to get under the dash and wire up all your gauges, switches, and lights from the backside. Yet this is one place where completely disassembling your car for restoration is a distinct advantage. If everything’s apart, you can do a lot of that wiring work with the dash out of the car, or at least partially removed.

No matter what, you’re going to want to handle this wiring with the seats, interior panels, and carpet out of the car. You are almost certain to have to route some wires behind and under those parts. Overhead dome lights don’t just glow by themselves! Plus, for the work that you really must do under the dashboard, it’s more comfortable to have room for your body to stretch out.

There are a couple of handy tools you’ll want to have. The first is a headlight - not the kind up at the front of the car, but a flashlight attached to a pair of safety glasses or a headband. Getting a good look at your working area when you’re under the dash is next to impossible, and sitting there with a hot droplight next to your cheek is even worse. You need a light that illuminates where you’re looking and doesn’t require one of your hands to hold.

Take your time under the dash and make sure each wire is solidly connected to its assigned post. Pay special attention to your grounding points, especially when there are multiple ground wires attached at a single point.

Hint...

You can use twist-ties to hold wires in place if they have a tendency to flop down. A twist-tie is reusable and easy to install and remove.

By far the most critical restoration points for your interior are your gauges. These instruments are delicate and must be restored by a specialist. Frequently, gauges such as speedometers and tachometers use magnets that may need to be freshened, and other gauges may include pressure switches and sealed tubes. Send all your gauges to a reliable restorer. Your marque club and national owner’s club should know who specializes in your car’s particular gauges.

Hint...

If you’re having a temperature gauge (for water or oil) restored, be sure to also include the temperature sender. The gauge restorer can calibrate your gauge to your particular sending unit for accurate readings.

When you’re having your speedometer restored, be sure to note the original mileage (if that reading is accurate) and then decide if you want the odometer to be zeroed or kept at the original mileage. Note that depending on the age of your car, it may be illegal to roll back the odometer for any reason.

Finally, if you’re converting your older 6-volt car to 12-volt operation, note that virtually all of your gauges will need at least a little work. 12-volt bulbs are generally larger than 6-volt, and any internal gauge electronics will need to be examined. Even simple gauges such as fuel level rely on electronics for accurate readings.

		1946 Packard: Interior electrical system
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The Popular Restorations feature car has a fairly basic interior electrical system. It has the usual switches for exterior lighting, turn signals, windshield wipers, instrument lighting and a clock. This Packard was originally ordered with no radio so there is a fair amount of empty space under the dash. Where it differs from most cars is that it has four heaters, six courtesy lights, and three cigarette lighters.

Back of dashboard - while still out of the car

The majority of the in-cabin wiring is handled by the “main” harness. The “body” harness is a long loom of wires that goes from under the dash, up into the ceiling above the driver’s door, and then all the way to the back of the trunk. The power for the rear courtesy lights, heaters, and cigarette lighters runs in the ceiling on the other side of the car.

When I purchased the car the gas gauge did not work properly. It read accurately until it got down to about three-fourths of a tank and then the needle would drop to empty. I took the sending unit to Abbott Instrument Restoration and had it rebuilt. Later on, after the car was running, the oil pressure gauge needle got stuck to one side so I had it rebuilt too. Now all the gauges work perfectly.

In a couple of cases the harnesses from Rhode Island Wiring did not include wiring components such as the wires that solder on the windshield wiper motor or the wires that go into the turn signal switch. The existing wires were in reasonably good shape so I put clear shrink tubing over them to ensure they were insulated properly and to keep them from breaking apart later on.

None of the switches needed to be replaced and all of the heater motors work well, so all in all the interior electrical restoration went very well.