NHTSA Complaint #11341560 — 2007 GMC ENVOY

THE DAYTIME RUNNING LIGHTS (DRL) AND THE LOW BEAM HEADLIGHTS DO NOT LIGHT EVEN WHEN THE DASHBOARD LIGHT SWITCH IS PLACED IN THE 'HEADLIGHT' ON POSITION. TROUBLESHOOTING REVEALED THAT THIS FAILURE WAS CAUSED BY THE BODY CONTROL MODULE (BCM) LOCATED BENEATH THE REAR SEAT. A DIGITAL LOGIC SIGNAL FROM THIS MODULE, BASED ON SENSOR INPUTS FROM THE AMBIENT LIGHT SENSOR, PARKING BRAKE AND WINDSHIELD WIPERS, IS PROVIDED TO THE UNDER-HOOD ELECTRONIC RELAY THAT ACTIVATES THE HEADLIGHTS. THERE ARE THREE POSSIBLE SIGNAL OUTPUTS FROM THE BCM...A LOGIC LOW (LIGHTS OFF), A LOGIC HIGH (LOW BEAMS FULL ON) OR A PULSE WIDTH MODULATED SIGNAL TO CREATE THE DIMMER DRL LOW BEAM INTENSITY. IF THE BCM FAILS, THE LOW BEAM HEADLIGHTS WILL NOT TURN ON. THERE IS NO AFFIRMATIVE INPUT TO THE ELECTRONIC RELAY FROM THE LIGHT SWITCH, NOT ROUTED THROUGH THE BCM, TO ACTIVATE THE LOW BEAM HEADLAMPS. THIS IS A MAJOR SAFETY ISSUE. WHEN THE BCM FAILS AT NIGHT, THE DRIVER HAS NO LOW BEAM HEADLAMPS. THE ONLY LIGHTS AVAILABLE ARE THE FOG LAMPS OR THE HIGH BEAM LAMPS, BUT ONLY AFTER SETTING THE DASHBOARD LIGHT SWITCH TO THE HEADLAMP POSITION. HEADLAMPS ARE A NECESSITY, NOT A OPTIONAL FEATURE. THEIR OPERATION SHOULD NOT RELY ON AN ELECTRONIC SUB-SYSTEM WHOSE FAILURE MODE PREVENTS THE LOW BEAM HEADLIGHTS FROM WORKING. THIS SYSTEM WAS DESIGNED THE 'EASY' WAY WITHOUT REGARDS TO VEHICLE SAFETY...NAMELY THAT WHEN THE DASHBOARD LIGHT SWITCH IS IN THE ON POSITION, THE HEADLIGHTS ARE ENABLED BY A SIGNAL DIRECTLY FROM THAT SWITCH. WITHOUT AN AFFIRMATIVE ENABLING SIGNAL FROM THE MANUAL DASHBOARD LIGHT SWITCH, THE SYSTEM AND VEHICLE OPERATOR IS AT THE MERCY OF THE BCM, WHICH COULD FAIL AT NIGHT OR ON THE WEEKEND (WHEN A REPAIR SHOP IS UNAVAILABLE) RENDERING THE VEHICLE DANGEROUS OR UN-DRIVEABLE.