Abstract: An automated test system makes voltage and resistance measurements. The breakout cable is connected between the vehicle electronic control module and the vehicle sensors and controls. Resistance measurements are made between a selected pair of connector pins of the breakout cable by connecting a current loop (which includes a power supply and a known resistance) through a first multiplexing circuit to the selected pair of pins. A voltage measuring circuit measures voltage across the known resistance and between the pair of pins. The voltage measuring circuit includes a second multiplexing circuit and a voltmeter. The second multiplexing circuit receives inputs from the various pins, as well as from opposite sides of the known resistance in the current loop. The second multiplexing circuit provides its output to the voltmeter for measurement. By measuring the voltage across the known resistance, and the voltage between the selected pair of pins, the resistance between the two pins can be derived.

Abstract: An automotive vehicle wheel alignment system uses a light source and a linear CCD to measure angles. A mask having a slit through which light from the light source is projected onto the surface of the linear CCD is interposed between the light source and the linear CCD. A microprocessor controls the light source and the linear CCD and uses an output from the linear CCD to calculate an angle between the light source and the linear CCD. The microprocessor uses a search algorithm to locate the center of the image projected on the linear CCD. Calibration data for the linear CCD is stored in an EEPROM.