stebo said:

Right I got two blue 6 LED interior lights for my punto mk2 off ebay,
fitted and worked but they stay on very dull when they go off, so then went halfords thinking my lights were crap, got another set fitted and have the same problem??? But if I put 1 normal bulb and 1 blue LED bulb in it all works fine??? :bang:
can someone help?????? PLEASE :worship:

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red said:

Stebo,

Are these LED lamps used in replacement of the existing interior lamps or wired as extras?

Either way, I think I can explain what's occurring. The Mk2 uses a body computer to control the interior lighting (exterior as well). It uses semiconductors to switch the 12V on. However, when the signal is "off", there is still a small current from the body computer. This is not enough to light a filament lamp but it can easily light LEDs. When you fit one of each type of lamp, the filament lamp sinks the current and effectively reduces the voltage below that needed to light the LEDs.

If you know what you're doing you could fix a resistor across the circuit to have the same effect as having a filament lamp there. I say "know what you're doing" because you'd need to select a resistor value to be low enough to pull the voltage below the threshold needed to light the LEDs but not so low as it gets hot when the lights are on. Having selected a resistor value (Ohms) you'd need to calculate maximum dissipation (Watts) to get the correct size.

For instance, here's the wattage worked out based on supply voltage of 13.8V for some typical resistor vaules:

100R - 1.90W
120R - 1.59W
150R - 1.27W
180R - 1.06W
220R - 0.87W
270R - 0.71W
330R - 0.58W
390R - 0.49W
470R - 0.41W

red

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