Q: How do rain-sensing wipers work? I love mine - it's like magic! Susan
A: In most of these systems, a rain sensor is located on the inside the windshield behind the rear view mirror. Infrared light is projected outward through the windshield glass at a 45 degree angle. Depending on how much light reflects back to the sensor (rain, snow or dirt scatters the light, reducing reflect-back), the wipers are turned on at an appropriate speed and delay frequency. Vehicle speed is often another input for automatic wiper operation.
Q: I have a 2018 GMC Sierra 3500 HD with the 6.6 liter diesel engine and Allison transmission. The truck generally gets quite respectable mileage, using about 10-11 liters of diesel per 100 kilometers (22-23 mpg) on the highway. From time to time, though, the fuel consumption abruptly increases from this to 16-17 liters per 100 kilometers (14-15 mpg) for about 20 minutes and then returns to normal. This is on level roads at the same steady speed and wind conditions. Fuel consumption will even remain at 4-5 liters per 100 kilometers (52 mpg) when coasting downhill where it normally drops to near zero. Why does this occur? Len
A: I believe what ...