Wiring Part III
Details of the switch circuits follows.
Windshield wipers
The GT 40 kit came with an after market (not Lucas) brand wiper motor with a four wire plug. Two wires activate the low and high speed circuits. The other two activate the park function. Using a battery charger as a power source (which is circuit breaker protected and thus preferable to a battery for this purpose) temporary connections were made to determine how the circuits should be wired. Connections were then made to the Lucas wiper switch, 35927. A GM Style plug was then added for ease of servicing or modifications. We are adding a Lucas windshield washer which looks vintage, so its power source was tapped off of the wiper power source as well. (Hard to believe, but one can see Lucas type windshield washers on some vintage photos, hence why not on a reproduction?).
Fuel pumps
Painless was the source for the two fuel pump relays, #30101. These are the weather proof version, for a bit of added security. We used a red relay wire on the left (port) switch and a green on the right (starboard) switch. All circuits were checked as they were completed while the components were sitting on the dinning room table.
Brake light
Here is a strange little extra we added. On one original GT-40, (I can’t recall which one at the moment), the mechanic placed a push button switch on the dashboard which activated the rear brake lights. When approaching a curve, the driver could push that button just before he applied the brakes to prompt the car following to hit his brakes prematurely. Ryan thought it could have real world applications, like signaling a tailgating car to back off. Wiring it involved nothing more than adding a pair of parallel wires with the brake switch at the brake pedal.
Lights
Originally we planned to place relays in the high beam, low beam and driving light circuits. But we decided to keep it simple. The Lucas headlight switch, S-31788 and the Lucas high – low beam switch, 34889, and the fused circuit supplied by Painless should be adequate to handle the power. However since the driving lights may be a halogen type light (we have not decided yet) we will likely add a relay under the front clip. All three switches are on the small switch panel to the left of the steering column. The blue high-low indicator is directly above the switch, so which switch to flip for high beams is obvious.
Auxiliary fans
The auxiliary fans will be activated with a temperature switch that goes on at 185 degrees and off 170 degrees, with an appropriate relay and fuse. Painless supplies the parts in their kit, 30129. However, the option of being able to manually override the thermostat switch was facilitated by a dash mounted switch. The switch simply grounds the connection to the thermostat, in parallel to the activation circuit. In addition the AC trinary pressure switch will also be wired into the circuit, so there will be three separate means of activation, which could work concurrently or independently depending upon the cooling needs of the engine.
AC and Heater
A small auxiliary panel was made to accommodate the controls for the heater and AC system, as noted in a previous post. One switch operates the fan, a second the AC temperature, and the third is a pull switch to control the water flow for the heater temperature. The fire system lever occupies the first position.
The AC / Heater blower uses a lot of power. It has four positions: off, low, medium and high. Using the charger amp gauge as a crude indicator, the high position draws around ten or more amps of power. That seems like a lot of power to draw through a small dash switch, so we decided to use the extra relay included with the Painless fuse box for the high speed blower circuit. We shortened the three wire harness going from the switch to the AC / heater unit, rewiring the orange – high speed blower wire into the relay circuit.