Led indicators flashing too quickly!

[Lordbenny]

So, they're not drawing enough current and flashing 3 x too fast even though the hazard lights flash normally. How do I fix this?

[Sam_68]

Are you using an electronic flasher relay rather than the traditional 'metal can' thermal resistive type?

[Lordbenny]

Sam_68 said:

Are you using an electronic flasher relay rather than the traditional 'metal can' thermal resistive type?

Thanks Sam, just ordered this:

http://www.ebay.co.uk/itm/12V-Relay-Fix-Flasher-LE...

From Hong Kong!

Edited by Lordbenny on Tuesday 29th November 20:08

[GreigM]

Just noticed this, all you need is a coupe of resistors wired in parallel to the led. You can buy the resistors in maplin for about 60p each.....some motorbike shops also sell them in packs.

[Sam_68]

True enough, but by the time you've buggered about finding the right resistance to give the flash rate you want, and hacked about the wiring to wire them in, you might just as well buy an electronic flasher unit that is plug-and-play and have done with it?

[robcollingridge]

Need to be careful with the resistors as they can get hot. There is quite a lot of power going into them. It's cheaper and easier to do it with electronics.

Rob

[Lordbenny]

So, just received this:

http://www.ebay.co.uk/itm/12V-Relay-Fix-Flasher-LE...

Plugged it in and......nothing. Is it cream krackered or am I doing something wrong?

[Steve_D]

Could be the pin configuration is different...I believe the markings are the Japanese system.
Look here Page 86 for a cross reference.

Steve

[GreigM]

In response to some of the above - there's no messing about with the flash rate, this is a simple case of making the circuit look like enough juice is being drawn to trick the flasher relay into thinking there's a working bulb there, when it does that it will blink at the correct interval, there's no variance here - they either blink normally or fast, there's no other variability.

This is the solution used in many kit cars and motorbikes around the planet. There's no heat issue with indicators because its not a constant current. As for figuring out the resistance required you'll find the guys in maplin can generally do it in their head, but from memory 2 of their highest rated resistors wired in parallel do the job very nicely - and at 60p a time its an easy fix. A bit of soldering and heat-shrink and you have a nice reliable solution - I'd venture a lot more reliable than a cheapo flasher relay from ebay - certainly mine have been working for over 2 years now.

[Lordbenny]

Steve_D said:

Could be the pin configuration is different...I believe the markings are the Japanese system.
Look here Page 86 for a cross reference.

Steve

Brilliant, just swapped the blue and white leads over and....hey presto, it works!

[Mr2Mike]

GreigM said:

There's no heat issue with indicators because its not a constant current.

That doesn't mean there is no heat issue. A 21Watt lamp on a 50% duty cycle is putting out 10.5 watts. The resistors will be a little less than that because the LEDs take a reasonable amount of current, but they certainly do get hot in operation. Far better to do the job properly with a load independent electronic flasher relay.

FWIW OEM electronic indicator relays have "blown lamp" detection built in so they mimic the operation of the older thermal relays. These relays can usually be modified to defeat this behaviour if you can get them apart and identify the IC.