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- Nov 10, 2014
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In preparation for replacing the license plate incandescent bulbs in my car with LED bulbs instead, I thought it would probably be a good idea to actually test the switching off of the "Lamp Monitoring (Cold) License Plate Lamps active" option first which on my 5K0937087R BCM is Bit 6 of Byte 23...
This I have proven to work just fine. If this coding option is active (factory default) and I remove both bulbs, the "bulb out" warning indicator comes on and I get told in my MFD that the offending bulbs are the license plate ones. If I deactivate the coding option and clear the fault codes, with no license plate bulbs fitted I get no recurring "bulb out" warning. Just what I need to happen so this is good news
So onto my next question regarding the other related license plate bulb coding value. This is Bit 7 of Byte 17 and is labelled "License Plate Light w/o Pulse Width Modulation (PWM) [LED Light]" (see screenshot below). The very end part in brackets suggests that I probably need to activate this option if I am going to be fitting LED bulbs (i.e switch off PWM). The question I have is do I actually need to activate this for LED bulbs, and if so then why exactly?
I understand that PWM is used to control the brightness (dimming) of incandescent bulbs, but what about controlling the brightness of LEDs? This can also be achieved with PWM so I'm not quite sure I understand why PWM would not be required for LED bulbs. If PWM is left switched on, would there be any detrimental effects of this on an LED bulb or the lighting circuit of the BCM itself?
This I have proven to work just fine. If this coding option is active (factory default) and I remove both bulbs, the "bulb out" warning indicator comes on and I get told in my MFD that the offending bulbs are the license plate ones. If I deactivate the coding option and clear the fault codes, with no license plate bulbs fitted I get no recurring "bulb out" warning. Just what I need to happen so this is good news
So onto my next question regarding the other related license plate bulb coding value. This is Bit 7 of Byte 17 and is labelled "License Plate Light w/o Pulse Width Modulation (PWM) [LED Light]" (see screenshot below). The very end part in brackets suggests that I probably need to activate this option if I am going to be fitting LED bulbs (i.e switch off PWM). The question I have is do I actually need to activate this for LED bulbs, and if so then why exactly?
I understand that PWM is used to control the brightness (dimming) of incandescent bulbs, but what about controlling the brightness of LEDs? This can also be achieved with PWM so I'm not quite sure I understand why PWM would not be required for LED bulbs. If PWM is left switched on, would there be any detrimental effects of this on an LED bulb or the lighting circuit of the BCM itself?