sixxgunscott Posted December 29, 2015 Report Share Posted December 29, 2015 My low beam headlamps suddenly do not work at all. Will not come on in Auto Setting or Manual. High Beams work fine. Fuse F74 which the manual states as the Headlamp Supply is OK. As both Right and Left Low Beams do not work, I am expecting the problem to be a Relay. Any ideas? Quote Link to comment Share on other sites More sharing options...
plus 3 golfer Posted December 29, 2015 Report Share Posted December 29, 2015 (edited) Are you still under the 3/36 B2B warranty? The Body Control Module controls the high / low beams (there are no switching components (relays) that can be replaced). The first thing to do is to verify that the low beam bulbs are okay. The headlight switch communicates with the BCM over the Local Interconnection Network (see quote below). The headlight switch (with fogs) has an MSRP of about $134. I keep harping on this but for about $30 one can get an ELM327 adapter to plug into the OBDII port and the ForScan App for a smartphone to scan modules for Diagnostic Trouble Codes. There are a number of DTC for the headlamps and BCM. "Low Beams The headlamp switch sends a status message over the LIN circuit to the BCM to indicate the headlamp switch status (position or a fault within the headlamp switch). If the BCM detects a fault from (or loses communication with) the headlamp switch, the BCM turns the parking lamps and headlamps on. This is normal behavior of the BCM design as a fault has been detected with the inputs from the headlamp switch. When the BCM receives a message requesting the headlamps on, it supplies voltage to the headlamp bulbs." Edited December 29, 2015 by Plus 3 Golfer Quote Link to comment Share on other sites More sharing options...
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