[eggcatcher]

Car failed MOT today because indicators were flashing too fast. I'd put Orange LED bulds into the lexus lights, when replaced with conventional bulbs they passed. I beleive the problem is that flashcontroller is set-up for 2x21watt bulbs, and as LED bulbs had far less resitance, they had too much current sent to them. Can anyone with an auto-electrical knowledge come up with any ideas to increase resistance, and allow me to legally put the LEDs back? Im able to do the job myself, but my electrical knowledge doesn't extend to designing new systems.

 

[LiDL]

you need yourself a couple of load resistors (ebay link)

these convert the same amount of power the bulb would use into heat instead of light therefore your car knows no different.

They are wired in paralell to the bulbs, and easy to install but please remember they generate a lot of heat so mount them somewhere safe.

 

[eggcatcher]

thanks

 

[Labrat of Larbert]

This is a common problem with motorcycles, where people fit often LED indiccators.
Most m/c dealers (and even Halfraulds) sell modified indicator relays which need less of a resistive load to function. For bikes they tend to come with make specific connections, but most cars use plug-in relays with standard bases.

 

[eggcatcher]

Whats the rating of those indicators? Will ordinary resistors do the same job?

 

[LiDL]

load resistors are different to normal resistors.

 

[eggcatcher]

are they the same as bike ones? Or do bikes use less current? If they are different which ones will I need? And if I fit the same ones to my brake light leds will it re-enable cruise control?

 

[Labrat of Larbert]

As standard bikes use 12volt 21watt indicator bulbs, and although there is no side repeater the loads on the relay are near enough the same as a car.
Car relays are usually found in or near the fuse box.
Bike relays, however are usually mounted on the bike's frame and each manufacturer tends to use a different terminal configuration.

Check the LED depot website for more information on the resistors.
As applying the brakes switches off the cruise control, it is quite likely that it is the voltage in the brake light circuit that is responsible for the switching action. In which case fitting a resitor (or one to each individual brake light) should re-enable the cruise control.

Not a problem with bikes as very few have cruise control as standard!

 

[Jrp210]

As applying the brakes switches off the cruise control, it is quite likely that it is the voltage in the brake light circuit that is responsible for the switching action. In which case fitting a resitor (or one to each individual brake light) should re-enable the cruise control.

Exactly that the brake lights acts as a circuit which needs a certain amount of current. As leds use next to no power at all then the circuit does not receive enough resistance. So it shuts down the CC. To get it up back and running you need to add a load resistor to the brake light circuit. The same ones you use for the indicators should work.

They do get hot while in use. So make sure its not touching any other wires or anything it's going to melt / set on fire.

 

[eggcatcher]

Do mI just need one anywhere on indicator circuit? Or 1 each side? And then 1 more for the brakes?

 

[Labrat of Larbert]

LEDdepot website gives several schematic diagrams for instalations.
http://www.led-depot.co.uk then select "Diagrams and Dimensions"

Seems safest to fit one resistor to each LED bulb assembly.

 

[eggcatcher]

Got the resistors yesterday, do it matter which wire I connect it too off the indicator circuit?

 

[Jrp210]

I dont think it does. As long as its in the circuit you should be fine.

 

[eggcatcher]

Ive now fitted them, and they make no difference, these are the ones fitted,
[ebay]370137681421[/ebay]
Was told they're the ones by craig at LED depot?

 

[LiDL]

try connecting it across the two, ie

 

[eggcatcher]

The second wire is green/yellow, is this not the earthwire?

 

[LiDL]

both the same thing.

 

[eggcatcher]

Still no slower, does it make a difference what direction the resistor sits?

 

[LiDL]

try the other way round.. then you tell me

 

[eggcatcher]

Nope, no good