LED reverse lights dimming when steering

VeeFource

Active Member
Dec 5, 2014
126
4
Got some canbus rated superbright LEDs for the reverse lights on our Sportrider. They worked fine for a few months but now they throw the 'bulb out' warning light every time I select reverse. I've reset the error in VCDS but it still does it every time. I could live with it but for some reason the bulbs dim a lot when steering or the engine is idling when warm since the error thing started. The bulbs are obviously not getting enough juice but I can't figure out why they used to work just fine and now they don't. Any ideas?
 

RUM4MO

Active Member
Jun 4, 2008
7,970
1,060
South Scotland
I'd guess that that bulb is now faulty as all these LEDs need to have a series voltage dropper and I'd guess CAN-BUS compliant ones will need a parallel resistor to make the current flow the same as a filament bulb. The battery on that car might have weakened and that would also account for the lower voltage at idle but all these cars will suffer a dip in supply voltage when the steering is demanded at low engine speeds.
 

VeeFource

Active Member
Dec 5, 2014
126
4
Wierd thing is they both dim the same amount. Though I guess one faulty bulb could maybe be tripping the canbus which then limits the voltage to them to prevent a serious earth fault?
 

VeeFource

Active Member
Dec 5, 2014
126
4
I'd think that your starting point must be to fit the original bulb(s) back in and see how that goes.

Yeah good shout. Current plan is to swap each of the LEDs with a bulb in turn to see if it's just the one faulty one triggering the error.
 
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