CWood: When the DRL are on (daytime with switch in AUTO position) and the brake pedal is pressed, dash lights dim and front marker lights(above the headlights) come on. When the switch is in any other position, or when full lighting(night time with switch in AUTO) is active, pressing the brake pedal turns all rear lights off. Where should I start?
Sparky: The lighting problem should either be damaged rear stoplight sockets/bulbs or poor grounds to the stoplight sockets. I would start with a visual inspection of those bulbs and sockets.
CWood: Could it be the light sensor itself? When I cover it with something, it doesn’t automatically turn the lights on. I can tap it and the full lighting comes on and the brake lights brighten, but only slightly.
Sparky: The ambient light sensor technically reacts to changes in light pretty quick. It however sends the signal to the BCM and it takes it’s dear sweet time to turn the lights on or off. It can take anywhere from 30 seconds to 2 minutes to react.
Refresh me on the light situation. Do we still have all rear lights going out at night when the brake pedal is depressed or has it changed any?
CWood: Currently, when the DRL is activated in AUTO mode, marker lights and all gauges and knobs illuminate (as they would when the headlights are turned on at night) when the pedal is pressed.(see photos in next reply)
Brake lights and turn signals work properly.
When full lighting (night time) is active, brake lights are barely discernible from running lights.
Sparky: As I understand your problem depressing the brake pedal during the day turns on the marker/parking lights along with the dash lights. At night with the headlights on you barely notice a difference when you depress the brake pedal.
Start your diagnosis by removing one stoplight bulb at a time and recheck the system. One of the bulbs is back feeding the parking/marker and dash lights. If the condition continues even with both bulbs removed locate the trailer light adapter in the left rear storage compartment and disconnect it. Let me know which action if any corrects the feed back problem. I never did receive the reply with photos.
CWood: Well, I’ve checked all the tail lights including the 3rd brake light. I looked for the connection in the side storage area, and found that someone hardwired the trailer connection into the harness. Going out now to figure out what they’ve done. It will never pull a trailer again, so I’m removing the 4 prong connector and wires.
CWood: Trailer wiring removed, all lighting works correctly! Thank Y’all So Much!!!!