DIY: How to install OEM LED number plate lights to pre-2007 E9x models
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    DIY: How to install OEM LED number plate lights to pre-2007 E9x models

    So I thought I would make this DIY after being asked numerous times about LED number plate lights for the E9x models on here. I tried the festoon approach, but the bulbs get very hot and don't last long.

    These are what I tried.

    Rather than wasting more money on festoons, I thought about the OEM approach as I didnā€™t want those Chinese 18, 20, 24 LED bulbs built in housings as they are too bright and the bulbs won't last as long if there are error cancel surface mount resistors inside. These usually crack over time, which means replacements needed. The same would apply to those festoon LED bulbs with built in smd resistors.

    Ended up getting these from ebay at a bargain price of £11 shipped BNIB considering they cost £16 each.

    First thing you notice is the connection to these LED housings. Old and new side-by-side.

    So instead of buying additional looms from the dealer, you can either make your own or do what I did and find some old PC mother board wires with the 2 pin connectors already attached.

    Perfect fit after a little experimenting with a 9V battery, I found that the -ve pin is nearest to the edge of the housing. You can see how the +ve green and -ve black wires are attached.

    Now you need to remove the boot lid trim so that you can access the wiring. This is held on by several push fit plastic expanding rivets. Pull out the old loom connectors so that they can be cut ready to attach the new LED housing wiring. Fit the new housings and feed the wiring through. The housings will click in place for a perfect fit and water sealed by the gasket.

    It will be obvious that a light error will come up on the instrument or i-drive display because these are LEDs and the footwell module relies on seeing a resistance on cold testing and measuring current on hot testing. The module does this by pulsing all the wires at the same time every couple of minutes and confirming condition of the bulbs. It also performs a cold test on a wake up signal, and stores the information before going back into sleep mode until the car is next switched on. Because these pulses are so quick, the bulbs don't have time to illuminate. Only the centre LED brake light and xenons are exempt for the cold test, otherwise there will be a flicker effect.

    I didn't want to put in any power resistors because they will become hot, so knowing about the pulses from the FRM, I thought it would be a better idea to tap the number plate circuit into the boot sidelight, which come standard on the E9x. This will actually make the LEDs part of the sidelight check circuit and the FRM is none the wiser. Ok, so if there is a genuine bulb out error, then I'm not too fussed if both the rear bulb and number plate light CC-ID errors are displayed, easy to change one or the other. Use lengths of wires (say 3 core household mains wire for example) to create the tap links for each side (for left and right bulb out errors when they do genuinely occur). Pic shows blade in-line connector already taped up with the tap secure. Connected to the +ve side light wire.

    Run the wire across and ty wrap. The wire is the blue one in my example.

    You can see how the blue wire (connected to sidelight wire shown previously), connects up to the number plate +ve wire with the red blade in-line connector. I also wanted this to be a fully reversible mod, so after cutting and stripping the wires to the old connector, I fed them into a 5A block connector together with the new LED bulb wiring. This makes it easy to cut the LED wiring and use the old connection and housing if needed, which will probably take less then 5 mins to do. Also save me loosing the connectors as I know where they are now

    Repeat for the other side.

    Test the lights first before tidying up.

    Now you just tape up the looms and ty wrap them out of the way.

    Late evening and night shots.

    So there you have it. A relatively cheap modification to make the car look more modern using genuine parts

  2. The Following 2 Users Say Thank You to NealP For This Useful Post:

    Ferret (02-04-2012),Ronnie (15-02-2013)

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