Technical Boot light
- Thread starter Uncle Beee
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Technical Boot light
The plot thickens. Having fitted the above light unit which works ok, a friend gave me a brand new Fiat unit with an LED bulb in it. So off with the old and on with the new. The only problem is it doesn't extinguish when the tail gate is closed, it just goes slightly dimmer. So I've replaced the LED bulb which is a small printed circuit board for a 5w cap less bulb which isn't as bright ( obviously ) and when I close the tail gate the light goes out. I have read that using LED bulbs in older model cars can incur problems. So I've gone from no boot light to a light that won't go out to a dim one that works as it should. The only saving grace with the exercise is that it's cost me in total £1.00 and that was for two 5w bayonet type bulbs from a local hardware store. 
Tomferrari517
Member
It's common for that to happen when you put on an LED light that consumes much less than an old fashioned bulb. I fitted an LED one to my boot and it also gets dim when closed, but I did a test leaving the parcel shelf open and car locked and the LED eventually does fully turn off after about 10-15 minutes which shouldn't be a problem since the battery drain in that period should be negligible or none at all.The plot thickens. Having fitted the above light unit which works ok, a friend gave me a brand new Fiat unit with an LED bulb in it. So off with the old and on with the new. The only problem is it doesn't extinguish when the tail gate is closed, it just goes slightly dimmer. So I've replaced the LED bulb which is a small printed circuit board for a 5w cap less bulb which isn't as bright ( obviously ) and when I close the tail gate the light goes out. I have read that using LED bulbs in older model cars can incur problems. So I've gone from no boot light to a light that won't go out to a dim one that works as it should. The only saving grace with the exercise is that it's cost me in total £1.00 and that was for two 5w bayonet type bulbs from a local hardware store.
Thanks for that. When I did the original test to see if there was power to the connector using a test lamp, I did as you say and left the parcel shelf up and closed the tail gate and the light went off immediately.
So where does the LED bulb get it's power from.
So where does the LED bulb get it's power from.
Tomferrari517
Member
I'm no expert or electrician, but I've read that the older type of bulbs require a load much higher than LED's to light up, so that's perhaps why the LED's are dim when you close the tailgate, they are able to use the residual load that wouldn't be enough to light an older bulb but is enough to light an LED, but feel free to correct me if I'm wrong.Thanks for that. When I did the original test to see if there was power to the connector using a test lamp, I did as you say and left the parcel shelf up and closed the tail gate and the light went off immediately.
So where does the LED bulb get it's power from.
It’s always poweredThanks for that. When I did the original test to see if there was power to the connector using a test lamp, I did as you say and left the parcel shelf up and closed the tail gate and the light went off immediately.
So where does the LED bulb get it's power from.
It’s the pathway to ground that’s switched
By the body computer.
Yes my electrical knowledge is somewhat limited. Your explanation though sounds good to me.
Thanks for your explanation as well koalar
Canbus compatible LEDs have extra resistors built it
I suspect, but haven’t tried, these will not glow
It’s quite a common problem with headlight conversions
I suspect, but haven’t tried, these will not glow
It’s quite a common problem with headlight conversions
Dimmed light occurs when that light is controlled by a transistor rather than by a relay or mechanical contact.
Nothing happens because that light remains dimmed.
Nothing happens because that light remains dimmed.
If I was to put the LED back in would it do any harm to the electrics of the car.
Yes it does go out after 5/10 mins so I'm happy with that.
Thanks to you all for the help.
Thanks to you all for the help.
