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So off the back of a previous question, I need to install a resister to my cluster in order for the LEDs in the indicators to work properly and not hyper flash.

Here is an image of the wiring that I found on Google:

enter image description here

My question is what wires are what? Ideally I just need to know the positive/negative for the indicators but understanding which wire powers the different lights would be beneficial.

  • While I welcome the edits. The resistor is going on the indicator wiring, not the brake lights – Andy Holmes Feb 5 '16 at 14:43
  • I meant "brake light" as in the entire housing (so all the wires), but I can see where it might confuse the questions meaning. – JPhi1618 Feb 5 '16 at 14:50
  • That's cool @JPhi1618 I knew the angle you were coming from :) Was just concerned that others may find it confusing – Andy Holmes Feb 5 '16 at 14:53
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I'm going to answer this in a general way because for someone to tell you what the wires mean, they would need to follow this procedure, or have access to detailed wiring diagrams for your car. You'll need a multimeter for this, and you'll have to take apart the brake light as if you were changing the bulbs so you have access to the bulb sockets.

I'm assuming you have light bulbs that look like this:

enter image description here

On that type of bulb, the whole metal base is "ground" and the little tips on the end that are typically made of solder are the "positive" contacts. Looking at the bulb socket, find the contact that touches the ground of the bulb. Put your meter in continuity mode, touch one probe to that contact and then touch each of the wire contacts where the car's wiring connects. This will be the ground wire. ALL of the bulbs in the light will probably connect to the same ground (my guess would be the brown wire which is common in German cars).

Now that you know what the ground is, you have two options. You can touch one probe to the contact in the socket that touches the end of the bulb if there is only one contact. This will allow you to find the positive on a single contact bulb.

The problem is that a blinker light may have two contacts, and you don't know which contact is the blinker positive.

Put the meter in Voltage DC mode, and turn on the turn signal. On the wiring connector, hold one probe of your meter (the black one, but it doesn't really matter) to the ground, and probe each of the other wires with the other. When you find the positive where the voltage is jumping up and down, that's the winner. Note that some digital meters might not be fast enough to show the voltage going up and down. In this case, all the other wires will show near-zero voltage, and the meter may just seem confused when probing the blinker wire.

Once the blinker wire is found, it's just a matter of cutting the wire in a convenient place and splicing in a "CAN light resistor". These are typically large 6 ohm resistors rated at 50W:

enter image description here

When mounting/hiding the resistor, keep in mind that they can get hot. They have to dissipate just as much power as a light bulb, so they can get as hot as a bulb. A blinker is normally only on for a short time, so heat may not be an issue, but if you use the same thing for an LED "running light" that stays on, heat will be an issue.

Almost forgot - what are the 5 wires probably for? Normally they would be (in no particular order):

  • Running light (+)
  • Brake light (+)
  • Turn Signal (+)
  • Reverse light (+) or Rear Fog (+)
  • Ground (-)
  • Thank you for this. In the cluster there is a brake light, fog light and indicator. Reverse light is in the bumper – Andy Holmes Feb 5 '16 at 14:44
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    Thanks, I didn't think about rear fogs... We don't really have those in the US, but a common mod for BMW/VW/etc enthusiasts is to install a "Euro (headlight) switch" that adds the rear fog capabilities. – JPhi1618 Feb 5 '16 at 14:53
  • Also, if your brake light socket assembly looks like this you can easily trace where the wires go just by looking at it. (image of BMW tail light found here ) – JPhi1618 Feb 5 '16 at 15:01
  • Unfortunately not, they look like this - pelicanparts.com/techarticles/MINI/… – Andy Holmes Feb 5 '16 at 15:24
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Blue Green is the indicator wire for the left rear, blue brown for the right rear. Assuming USDM.

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If you are looking to figure out which wire goes to which, an easy way to figure this out is to have a source which produces 12vdc and has the two leads for (+) and (-) with probes attached, plus a pad and pencil to mark down what is what.

After you have your 12v source and other supplies to get started, take the bulb section out of the housing so it looks like this:

enter image description here

Use your probes to figure out which is which. While this may not hold true in your case, Start by putting the negative (-) probe on the connection which would match to where the black wire goes to the prong inside the housing (where the connector inserts to the light bar). Black or green are usually universally used as the ground/earth. This may not hold true for the Mini, but it's a good starting point. Next place the positive lead to any other prong inside the housing to see if something lights up. If something does light up, you are in pretty good shape. Write down what you've discovered. If nothing lights up, then your negative probe is probably in the wrong spot. You will need to try a different combination until you get something to light. Use this trial and error method to figure out what connects to what and write it all down. When you've figure out what is what, you'll have created a map for the wiring.

This same basic method can be used in many different situations. Just know, you aren't going to blow anything up in the process, even if you put the power in the wrong direction. It shouldn't light if it is backwards, but it won't hurt anything.

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