LED indicators / flashers

[Dave H]

Wondering if anybody's tried these ?
It says no resistor, ballast or change of relay is required however designed for modern vehicles, may not work on classic vehicles.
I will ring them on Monday to find out more.

https://www.classiccarleds.co.uk/products/canbus-bright-amber-led-indicator-bulbs-ba15s-p21w-glb382

[scoot]

I've bought a lot of LED bulbs from them over the past 2 years and think they are a great company, but I can't speak to the effectiveness of this particular product in your application.  I would say go for it and report back...

[Dave H]

It has been pointed out in previous posts that you cant use LED for your turn signals without fitting an inline resistor or rigging up an LED compatible flasher unit. Low voltage LED bulbs simply flash too quickly without this.
These new bulbs might of cracked the problem. Fingers crossed.

[clunker]

I used a 60ohm 50w resistor, in parallel with a regular LED bulb, for indicators: relay runs at correct speed.

Issue is where to mount the resistors, as they are simply a heat sink = get hot. I put back my incandescent bulbs for now whilst I figure a suitable spot.

Note they do not have to be adjacent to the bulbs - think I will put two of these resistors on each sides indicator circuit (two because they can act for front and back on same circuit, and in parallel with each other and with each circuit). Will mount these in the trunk area on a suitable surface to dissipate heat. The indicator circuit wiring is also more accessible/ weather protected back there.

These resistors in indicator circuits will also solve relay problem for both indicators and hazards.

[Dave H]

OK, so got i just got off the phone with "www.classiccarleds", unfortunately they will not work in our cars after all.
These bulbs only work in modern cars with electronic management systems, not with old mechanical flasher units such as ours.
What a shame, i thought they must of put a resistor in a bulb or something to get round it but no, so its back to the drawing board.
What he did say was not to use resistors  in line, they get hot and put a load on the wiring.
He also said to get an LED compatible flasher unit , somehow wire this inline and any LED bulb will work.

[teahead]

https://www.sl113.org/wiki/Electrical/FlasherRelay

Stuff the guts of an electronic relay into your old flasher.

[Dave H]

2 ways to do it.
I think your idea Charles ( clunker ) is by far the easiest but I’m real uneasy about the load on the wiring and the heat produced by the resistors which if I’m right are about 3 inches long and will get as hot as the bulb did.
Other way is to simply fit 2 LED relays .
If I’ve got this right and I seldom do, swap the flasher relay for an LED relay. (Item 12 )
Then bypass the hazard flasher relay ( item 26 ) by removing  wires L, R & 30 only and link into the switched earth side of 31 within the relay, now add a 2nd LED relay to these 3 wires , assuming you join L & R the hazard switch will still function as normal. Probably missed something and please correct me if have.
All this is reversible which is my aim and only 4 wires have been disturbed .

[clunker]

assuming you join L & R the hazard switch will still function as normal

I think if you join L & R, then when you use the regular indicators both sides will flash as you have bridged the circuits - thats why they used a double pole relay at 26.

Far point on the wires/heat - though to be fair the load on wiring is same as for incandescents. In the end maybe incandescents for the indicators is really ok versus relay rebuilds - LEDs for other lights the more effective change.

[Garry]

I have fitted some led’s from this company with out using any resistors.


Gary

[Dave H]

Well spotted Charles, you are the kiddy, i went to bed thinking about this last night, you are correct, it would indeed bridge the flasher circuit.
In summary LED relays will not work in our cars due to the amount of invasive work involved as Charles points out..
2 resistors would be an easy fix but unsure of heat and load on the wiring but agree it should be no more than incandescents.
Yes, its probably best not to use LEDs for indicators and concentrate on gains elsewhere, i will upgrade to the brighter indicator bulbs as the tech manual points out .. 43% brighter will work for me.

P3497 - 43% brighter than standard bulbs. The Krypton-charged P3497 single-filament bulb replaces the following original bulbs:

European P21W or 7506
American 1156, 1073, or 1141

Gary, did you end up putting LEDs in your indicators and if so, how did you do it ?

Thank you all for your brilliant advice, this group is fantastic.

[66andBlue]

Reading through this and similar posts and the tech. manual it is clear that an electronic turnsignal/flasher relay is required when installing LED turn signal bulbs (https://www.sl113.org/wiki/Electrical/FlasherRelay).
But what if a car, e.g. late 280SL, has already the Bosch illuminated electronic relay that combines the thermomagnetic turn signal controller and the mechanical emergency/hazard relay? https://www.sl113.org/wiki/Electrical/HazardWarningLights
Is this electronic hazard/emergency relay compatible with LED bulbs? Or does one need to add resistors?

[Chris Long]

Mine is a late 280Sl - VIN 015193 and yes I needed an LED flasher as the thermomechanical flasher doesnt get enough current draw with LED bulbs to work correctly.

I mapped out a very easy and reversible solution in this thread https://www.sl113.org/forums/index.php?topic=30927.0

[66andBlue]

Correct, IF you have the thermomechanical flasher unit.
But when you have the later Bosch unit installed you do NOT have it any longer, it is not functional. Thus my question, will LED bulbs work with the Bosch flasher relay?

[Chris Long]

What part number Bosch relay do you have?

[66andBlue]

The one shown in my link to our technical manual Bosch #0335 240 002:

[66andBlue]

...
Is this electronic hazard/emergency relay compatible with LED bulbs? Or does one need to add resistors?

Since I received no answers I did some crude testing and found out that with two pairs of LEDs hooked up to the switch the turn signal function will not work although it did with normal incandescent bulbs. Pulling the knob to test the emergency flasher function the LEDs started flashing as did the bulb inside the knob. However, the frequency was faster.
Why one works with LEDs and the other does not I cannot explain, perhaps others can.

[Chris Long]

Not enough resistance in the circuit - an led flasher is v easy to install under dash and reservable.