LED bulbs

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z3steve
Joined: Thu 03 Feb, 2011 23:01
Posts: 155

  Z3 roadster 2.2i
Location: Tunbridge Wells

LED bulbs

Post by z3steve »

Hi all, I thought id go for the led bulbs all round and no matter what bulbs i put in (CANBUS or not) they still flash too quick. I bought some non CANBUS bulbs to start with and the flashing was too quick - so I got CANBUS ones - and they still do the same. Is there a different flasher relay I can get or another way to solve the issue?

Cheers!

Steve
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Southernboy
Joined: Thu 07 Oct, 2010 12:39
Posts: 6436

  Z3 roadster 3.0i
Location: Johannesburg

Re: LED bulbs

Post by Southernboy »

You can fit an in-line resistor on the wires which feed to the indicator bulbs. A 5 - 7 watt resistor should be sufficient. The resistor decreases the wattage of the current pasing to the LED.
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Robert T
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Joined: Mon 12 Jun, 2006 10:35
Posts: 10170

  Z3 roadster 1.9
Location: Cheshire

Re: LED bulbs

Post by Robert T »

Indicator bulbs need to draw a certain amount of current for a standard flasher relay to flash at the correct speed. You have two choices - either swap the flasher unit for one designed to drive LEDs, or fit a load resistor in PARALLEL with the LEDs to increase the current to the LED whilst maintaining the same voltage (I'm not sure electrics are Barry's strong point! :lol:). There will already be a series resistor built into the bulbs to drop the voltage from 12v to about 3v, as they will be designed to plug straight into a 12v system - the load resistor is purely for getting them to flash at the correct rate.

I have done both on the Sprite - the load resistors were easy enough to fit on that, but you have to modify the wiring slightly to break into the loom just before the LED bulb - if you use off the shelf load resistors, you'd need one per bulb - or you could fit one resistor with one third(ish) of the resistance per side (i.e. three bulbs per side).

Solid state LED flasher units are fairly readily available now and I just sourced one which is a direct replacement for the one on the Sprite. You'd need one to match the exact pinout of the one on the zed, but they will like be the same in pretty much all BMWs of that age, so someone will do one.

The LED flasher unit would be my choice, as they flash at the same rate regardless of load and the one I got can handle a mixture of LED and incandescent bulbs, up to 30W. Using one of these, the whole system draws much less current.

Out of interest, what do the hazard lights currently do on you car? Do they flash at the correct rate or not? And what about the alarm? If these are a problem, then you would be better off with load resistors, otherwise you'd have more bits to replace, and I'm not sure what you'd do with the alarm!

Cheers R.
Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
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Southernboy
Joined: Thu 07 Oct, 2010 12:39
Posts: 6436

  Z3 roadster 3.0i
Location: Johannesburg

Re: LED bulbs

Post by Southernboy »

..... thanks for that Rob....How did you guess that electrics was a weak area of mine??? :D
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Z3 Upgrades and Additions
z3steve
Joined: Thu 03 Feb, 2011 23:01
Posts: 155

  Z3 roadster 2.2i
Location: Tunbridge Wells

Re: LED bulbs

Post by z3steve »

Thanks for the replies so far - much appreciated.

The flashes are all too fast with the LED fitted. The front indicators should be fairly easy to fit an inline resistor but how do you go about doing the ones at the rear? the bulbs are in plastic holders unless you start taking all that to bits to find the cable?

Thought there must be an easier way of just replacing the flasher unit to deal with LEDS - but I dont know where to look to source one. If anyone finds one on the 'net and can post a link Id be most grateful :wink:

Cheers, Steve
z3steve
Joined: Thu 03 Feb, 2011 23:01
Posts: 155

  Z3 roadster 2.2i
Location: Tunbridge Wells

Re: LED bulbs

Post by z3steve »

Oh and the stop and tail LEDS dont work at all.........

Driving me nuts lol

Steve
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Robert T
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Joined: Mon 12 Jun, 2006 10:35
Posts: 10170

  Z3 roadster 1.9
Location: Cheshire

Re: LED bulbs

Post by Robert T »

All the bulbs on each side will be wired in parallel, so in theory a single load resistor of the right resistance would do the trick. The load resistors I bought came with the bulbs and were designed to induce the same load as the bulb they replaced. With these particular resistors, you'd need three to achieve the same effect (as you've replaced three bulbs), though I suspect the side-repeater is a lower wattage than both the front and rear. You do need to be careful where you fit such a resistor (or resistors), as the wiring loom will only be designed to carry the current for the bulbs it serves. The resistors are also known for getting hot, so beware of where you mount them!

I just checked the place I got my LED flasher unit from and none of them look like they will fit the zed. I did see some on autobulbsdirect.co.uk, but their specifications were a bit vague and the picture for the type I wanted seemed to show the wrong pinout. It needs to be one that is designed to be direct replacement.

I did find a thread on bimmerfest detailing an LED upgrade on a Z3 - it's a while old - in the end it looks like the guy modified the relay himself - see https://www.bimmerfest.com/forums/showt ... 12&page=12

Regarding my earlier questions, I think I just answered them, as in the relay is described as Hazard Warning Relay and the ETM shows that it is used for both hazards and indicators. BMW used it on lots of models (see http://bmwfans.info/parts-catalog/61361388547/), so one would hope that there would be an off the shelf unit you could use, though I haven't found one!

Cheers R.
Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
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Robert T
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Joined: Mon 12 Jun, 2006 10:35
Posts: 10170

  Z3 roadster 1.9
Location: Cheshire

Re: LED bulbs

Post by Robert T »

LEDs are polarity sensitive - unlike a conventional bulb, they need to be connected the right way round to work. I seem to recall reading that the taillights might be wired the opposite way round! Take a look at the bimmerfest thread above and see what the guy with the Z3 did for his (there are 12 pages, so it might take a bit of finding!).

Cheers R.
Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
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