Abstract: An automotive vehicle exterior illumination circuit includes a main headlamp circuit, including a headlamp switch, for operating the headlamps at full intensity and a DRL control incorporating voltage-dropping resistance in a daytime running headlamp circuit for achieving reduced intensity daytime running illumination. The resistance is provided by a plurality of resistance wires mutually connected in parallel in a wiring harness carrying electric current to the headlamp filaments. The headlamp switch is provided not only with the usual set of normally open contacts that close when the headlamp switch is turned on to provide full nominal supply voltage to the similarly rated headlamps, but also a set of normally closed contacts that allows DRL operation when the headlamp switch is off but disallows DRL operation when the headlamp switch is on.

Abstract: A circuit for implementing dual dimmer controls in an automotive vehicle having right- and left-side driver stations. The circuit can be used with existing control switches, thereby avoiding changing or redesigning those switches. The circuit uses several relays, connected in a novel configuration with other existing components.

Abstract: A circuit for implementing dual wash/wipe controls in an automotive vehicle having right- and left-side driver stations. The circuit can be used with existing wash/wipe control switches and comprises solid state diodes, a single selector switch, and a single relay, connected in a novel configuration with other existing components. The selector switch selects a wash/wipe switch at either one of the driver stations to have control over an electric-motor driven wiper motor to the exclusion of a wash/wipe switch at the other driver station. Diodes couple each wash/wipe switch to a wash/wipe electronic control module that in turn operates the electric-motor driven wiper motor.

Abstract: A circuit for the electrical system of an automotive vehicle, such as a truck, interfaces a brake switch, a combination turn signal/hazard warning signal switch, and an engine electronic control module (ECM) that has two separate brake signal inputs. The circuit is especially useful when the vehicle engine has a power take-off (PTO) to prevent unintended interruption of power flow through the PTO to an accessory device, such as a salt spreader, hydraulic pump, air compressor, etc. The circuit can be fabricated from conventional circuit components. A pre-existing vehicle can be retrofitted with the circuit by a jumper harness.

Abstract: A circuit interfaces a brake switch and a combination turn signal/hazard warning signal switch with a system electronic control module (ECM). The circuit is especially useful when the vehicle has an engine idle shut-down system that requires an input for distinguishing brake application from brake non-application, wherein such an input is derived from operation of the interface circuit. The circuit also employs a relay, which, along with the brake switch, the system ECM, and the combination turn signal/hazard warning signal switch, are connected such that the brake switch carries only the relay coil load, live D.C. voltage, which is independent of the position of the vehicle's ignition switch, is fed through the relay, and a hazard warning signal is prevented from having any effect on the ECM via the relay.

Abstract: An automotive vehicle electrical circuit that, when the hazard warning switch is in the on position, provides for the front lamps on both sides of the vehicle to continue to flash on and off when the stop lamp switch is actuated to continuously illuminate the rear lamps on both sides of the vehicle. The invention enables a pre-existing lamp control circuit to be cost-efficiently adapted to this form of control with only relatively minor modifications, namely the addition of two diodes and a minor change to the pre-existing turn signal switch. The invention may also be used to advantage in the production of new vehicles.