Bad sensor causes truck to think it's always night

Brad Bergholdt / McClatchy-Tribune News Service

Q: The daylight/nighttime sensor system of my 2000 Chevrolet Silverado 1500 is locked on the nighttime setting, which keeps the headlights on during daylight and also keeps instruments and digital clock/radio lights dim. Would this most likely be a defective sensor? Can the sensor be replaced without dismantling the dashboard? I tried cleaning the sensor but that didn’t change anything.

— Stan Burnett

A: Stan, it sounds like your Silverado’s ambient light sensor has failed or there is a faulty electrical connection between it and the truck’s body control module. This device, about the size of a small grape, is located next to the left defroster duct, and changes in electrical resistance with varying light levels. In bright light, resistance is low, and in darkness, resistance goes high. It’s a good idea to occasionally clean the sensor’s lens, and try not to obscure its exposure to light with a dash pad or errant Kleenex box.

Renewal of the $16 sensor requires removal of the instrument panel bezel, passenger assist handle, and upper trim pad, which seems like an intimidating chore. It’s not really that bad — perhaps a 30- to 45-minute job with good instructions and a few simple tools: www.justanswer.com/chevy/2ae2v-2001-chevy-ambient-my-automatic-headlights-turn-ignition.html.

Another option is to circumvent the sensor by inserting a 1,000-ohm resistor — this simulates ample light — into the circuit at the two appropriate terminals of the BCM, which is under the instrument panel, and easier to get to. This method is used by police agencies and other folks who don’t care for the automatic-only headlight light switch these trucks and some other vehicles were equipped with, because it has manual “on” but no “off.” Sorry, I need to stop short of guiding you down this road.

Q: This is not a story about the Energizer Bunny; it’s the story of my 1993 Nissan Quest. I purchased the Quest from my in-laws. The usual story for a vehicle owned by a retired couple; they only drove to the doctor’s office and to go shopping. I started using the Quest as my commuting car and added 10 years of Boy Scout outings, plus towing my boat to go duck hunting on weekends. The miles started to roll up. I really never thought much about it until I hit 300,000 miles on Oct. 13, 2008, and today it has 425,725 miles.

I attribute my good luck with performing routine maintenance as well as oil changes every 3,000 miles. By the way, I have three additional cars: a 1996 Ford Bronco with 202,000 miles, a 1998 Ford Explorer with 220,000 miles, and a 2005 Ford Escape with 132,000 miles. My fleet of cars is at 979,725 miles. I think this would make a nice article for your column.

— George Lallas

A: Yes, it does! It’s been many years since we’ve looked at high-miler vehicle stories. How about others writing in with theirs, and I’ll try to share them.

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